Major interaction on record — check this product against your medications before combining. Based on 11 of 12 ingredients. Check your meds →
Dietary supplement

Stimul8 Hardcore Grape Grenade Ingredients & Drug Interactions

by FINAFLEX

Stimul8 Hardcore Grape Grenade label
See full label image
Powder Category: Other Combinations
Most serious interaction: Major
Clinical methodology reviewed by · Updated Sep 16, 2026 · Label data from the NIH DSLD
What is this page for?

First and foremost: checking Stimul8 Hardcore Grape Grenade against your medications. The heart of this page is the interaction checker and the full interaction report — how this product’s ingredients may interact with prescription and over-the-counter medicines you may be taking.

Around that, we add a pharmacist’s high-level view of the product as a whole — what’s inside, the evidence for its stated use, how transparent the label is, and what safety data exists — so you can see the full picture in one place. It’s educational information from our licensed clinical databases and the clinical staff at HelloPharmacist — not medical advice — and we don’t sell or endorse products. Our editorial policy

The interaction bottom line Most serious interaction: Major

Stimul8 Hardcore Grape Grenade is a dietary supplement by FINAFLEX with 12 active ingredients. Its ingredients are commonly taken for bone health and osteoporosis prevention, dietary calcium deficiency, heartburn relief (calcium carbonate antacids).Based on those ingredients, 1,494 medications have a known interaction with it, the most serious rated major. The ingredients most likely to interact are BioPerine, Citrus aurantium Extract, Schisandra chinensis Berry Extract. Use the checker below to test your specific medication, or read the full HelloPharmacist Interaction Report.

Jump to a section

Check Your Meds Against Stimul8 Hardcore Grape Grenade by FINAFLEX

Ask about any prescription or over-the-counter medication and we check it for interactions with Stimul8 Hardcore Grape Grenade by FINAFLEX — and tell you which ingredient is responsible.

Pharmacist-reviewed data Checks every ingredient Answer in seconds
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HelloPharmacist Scorecard of Stimul8 Hardcore Grape Grenade by FINAFLEX

Our pharmacy team’s full take, with four database checks built into the cards below — a summary of what is known, not a grade of the product itself.

From our pharmacy team — supplement deep dive

Generated from HelloPharmacist’s pharmacist-curated databases and editorial rules · Last generated Jul 11, 2026

What’s inside

Full disclosure
Ingredient Transparency · database check
Full

Every active ingredient lists its own amount on the label.

Why this rating?
  • The label discloses an exact amount for 12 of its 12 active ingredients.
  • No proprietary blends here — you can verify the dose of every single component.

Stimul8 Hardcore Grape Grenade contains 12 active ingredients designed to support athletic performance and mental focus. Calcium supports bone health and muscle function, while L-Tyrosine, L-Theanine, and Alpha-Glycerylphosphorylcholine (Alpha-GPC) are amino acids and choline compounds that support cognitive and physical performance.

Beta-Alanine is an amino acid that buffers acid buildup during intense exercise. Citrulline Malate supports blood flow and endurance; Agmatine Sulfate supports nitric oxide production; and Betaine Anhydrous supports muscle function and hydration.

Caffeine delivers mental alertness and physical performance boost. BioPerine (black pepper extract) enhances absorption of other ingredients.

Schisandra chinensis berry extract and Citrus aurantium extract (bitter orange) round out the formula with traditional performance support compounds. The powder also contains inactive ingredients including malic acid, natural and artificial flavors, citric acid, gum arabic, sucralose, silica, calcium silicate, potassium citrate, and acesulfame potassium.

Does it work?

Strong evidence
Evidence for Intended Use · database check
By FDA rules, dietary supplements can’t claim to treat, cure, or prevent disease — so labels speak in careful marketing language. We discern each product’s intended use from its name, label claims, and label statements, then grade the clinical evidence for that use. How these ratings are computed
Strong

Clinical evidence supports at least one of this product's ingredients for its stated purpose.

Why this rating?
  • The label markets this product for: Energy, focus, and athletic performance.
  • We looked for evidence on: Athletic performance, Cognitive function, Fatigue, Attention deficit-hyperactivity disorder (ADHD), Exercise-induced muscle damage, Exercise-induced muscle soreness — and 4 related terms.
  • The strongest evidence on file: Caffeine is rated "Likely Effective" for Athletic performance (Natural Medicines).
  • Also on file: Caffeine is rated "Likely Effective" for Mental alertness.
  • Also on file: Tyrosine is rated "Possibly Effective" for Cognitive function.

Evidence for most ingredients in this product is limited or mixed. Caffeine is likely effective for mental alertness and athletic performance.

L-Tyrosine is possibly effective for cognitive function and memory. Beta-Alanine and Agmatine are possibly effective for athletic and physical performance, though results vary by individual.

L-Theanine is possibly effective for cognitive function. Calcium is effective for bone health and muscle function.

Alpha-GPC is possibly effective for Alzheimer disease but evidence for cognitive function in healthy adults is insufficient. Betaine Anhydrous is possibly effective for certain metabolic conditions but evidence for athletic performance is not established in the data we hold.

Schisandra, Citrus aurantium, and BioPerine lack sufficient evidence to establish their effectiveness for general athletic or cognitive use. Overall, this is a multi-ingredient formula, and individual results depend on your body's response to each compound.

The evidence, ingredient by ingredient Calcium Tyrosine Beta-alanine Black Pepper Theanine Agmatine Caffeine Alpha-gpc

How safe is it?

Well-documented data
Safety Information · database check
Well characterized

Adverse-effect, pregnancy, and general safety data are on file for most of these ingredients.

Why this rating?
  • We hold adverse-effect (side-effect) data for 11 of the 11 matched ingredients.
  • Pregnancy & breastfeeding safety ratings cover 11 of 11.
  • General safety write-ups exist for 11 of 11.
  • Remember: this measures how much safety information exists. Thin data is not the same as being safe.

When taken at recommended doses, most ingredients in this product are generally well tolerated. Calcium is generally well tolerated but high doses can cause constipation, bloating, or heartburn, and there is some concern about very high intakes (over 2000 mg daily) and prostate cancer risk in men.

Caffeine is generally safe in moderate amounts but can cause anxiety, jitteriness, insomnia, headache, and dependence with regular use; high doses may increase cardiovascular risk. Beta-Alanine commonly causes harmless tingling and flushing on the scalp and body within 20 minutes, lasting about an hour.

L-Tyrosine, Agmatine, L-Theanine, and Alpha-GPC are generally well tolerated but long-term safety in humans is not well studied. Bitter orange can raise heart rate and blood pressure, especially when combined with caffeine or other stimulants, and poses risks for people with heart or blood pressure conditions.

Schisandra is generally well tolerated short-term. Common mild side effects across the formula may include headache, nausea, diarrhea, and stomach upset.

Do not take this product if you are pregnant or breastfeeding without talking to your doctor—several ingredients lack adequate safety data in pregnancy and lactation.

Side effects, ingredient by ingredient Calcium Tyrosine Beta-alanine Black Pepper Theanine Agmatine Caffeine Alpha-gpc

Meds to double-check

Major interaction found
Known Interaction Concern · database check
Major identified

At least one ingredient has a documented Major-severity interaction. Check your medications for a personalized result.

Why this rating?
  • 9 of the 11 matched ingredients can interact with medications — Schisandra, Calcium, Black Pepper, Bitter Orange, Caffeine, among others.
  • The most serious interaction on file is rated Major.
  • Some involve high-stakes drug classes: anticoagulant / antiplatelet drugs; immunosuppressants / transplant drugs; diabetes medications; heart-rhythm medications; lithium; Parkinson's medications.
  • For scale: 1,495 individual medications appear in the full list. A big number alone doesn't make a product dangerous — what matters is whether YOUR medication is on it, so run yours through the interaction checker on this page.

Before taking this product, check if you use: HIV integrase inhibitors (dolutegravir, elvitegravir); intravenous ceftriaxone; monoamine oxidase inhibitors (MAOIs); blood pressure or diabetes medications; seizure medications (phenytoin, carbamazepine, phenobarbital); blood thinners (warfarin); or any drug metabolized by liver enzymes (midazolam, tacrolimus, cyclosporine, voriconazole, theophylline, atorvastatin, rifampin). The caffeine and bitter orange in this product significantly amplify the risk of serious cardiovascular effects when combined with stimulants or ephedrine.

Check your own medication Run your meds through the checker above

The bottom line

Scorecard at a glanceFully disclosed formula with clinical evidence supporting its stated purpose. Major medication interactions have been identified, and safety information is well characterized.

Stimul8 Hardcore Grape Grenade is designed for athletes and fitness enthusiasts seeking a pre-workout boost. If you take any prescription medications—especially HIV drugs, blood pressure or diabetes medications, seizure medications, blood thinners, or psychiatric drugs—you must check your exact medications with our tool before starting.

Do not combine with energy drinks, other caffeine sources, or stimulant products. Talk to your pharmacist if you have heart, blood pressure, or thyroid conditions, or if you're pregnant or nursing.

Educational only — not medical advice; always confirm with your pharmacist. Our editorial policy · How we use AI

Assessment coverage: 11 of 12 active ingredients matched to our full ingredient reviews (monographs). Based on the product label dated Jul 24, 2025.

This Scorecard evaluates available label information, ingredient evidence, and known medication-safety considerations. It does not independently verify product identity, purity, potency, contamination, or manufacturing quality. How these ratings are computed

At a glance

General information

Key facts about Stimul8 Hardcore Grape Grenade, straight from the product label.

Brand FINAFLEX
Barcode (UPC) 810020721218
Net contents 18.5 Ounce(s); 526 Gram(s)
Market status On market
Date entered into DSLD Jul 24, 2025
DSLD ID 334795
Product type Other Combinations
Supplement form Powder
Dietary claims / uses Nutrient, All Other, Structure/Function
Intended target group(s) Adult (18 - 50 Years), Women (not pregnant or lactating)
From the label
Everything in this section is reproduced from the manufacturer’s own product label — it’s the label speaking, not HelloPharmacist. We show it so you can see exactly what the maker states; we don’t verify or endorse those statements.

Supplement Facts

The label details for Stimul8 Hardcore Grape Grenade by FINAFLEX, sourced from the NIH Dietary Supplement Label Database.

Supplement Facts

Daily Value (DV) Target Group(s):
Adults and children 4 or more years of age
Minimum serving Sizes:
8.75 Gram(s)
Maximum serving Sizes:
17.5 Gram(s)
Servings per container
30
UPC/BARCODE
810020721218
IngredientAmount% DV
Calcium80 mg6%
L-Tyrosine500 mg--
Beta-Alanine3200 mg--
BioPerine5 mg--
L-Theanine150 mg--
Citrulline Malate6000 mg--
Agmatine Sulfate750 mg--
Caffeine350 mg--
Alpha-Glycerylphosphorylcholine300 mg--
Betaine Anhydrous2500 mg--
Citrus aurantium Extract100 mg--
Schisandra chinensis Berry Extract150 mg--

Other ingredients: Malic Acid, Natural & Artificial Flavors, other Natural flavors, Citric Acid, Gum Arabic, Sucralose, Silica, Calcium Silicate, Potassium Citrate, Acesulfame Potassium

Tap any ingredient to jump to its full detail below.

Label statements
These statements are the manufacturer’s wording, reproduced from the product label — the label is saying it, not HelloPharmacist. We don’t verify or endorse them.
Suggested/Recommended/Usage/Directions

Suggested use Mix 1 serving (1 scoop) of STIMUL 8 Hardcore with 8-16 fl. oz. of cold water and consume immediately. Do not exceed 1 serving (1 scoop) of STIMUL 8 Hardcore daily. For maximum effectiveness drink STIMUL8 Hardcore 15-30 minutes prior to physical activity. To test tolerance start by mixing 1/2 serving (1/2 scoop) into same amount of water.

Brand IP Statement(s)

BioPerine is a registered trademark of Sabinsa Corporation, USA.

Formula

BioPerine

6 g Citrulline malate 2:1 350 mg Caffeine Grape Grenade Natural and artificial grape flavor with other natural flavors

Seals/Symbols

GMP Certified Certified Good Manufacturing Practice U.S.A. Made Domestic & Imported Materials FDA Registered Facility

Formulation

Xtreme energy for hours Endurance & performance Razor focus

Extreme Training partner

General Statements

Redefine yourself with SIMUL8 Hardcore

Find us online: Instagram Facebook TikTok YouTube www.FINAFLEX.com

Precautions

Warning: Keep out of reach of children. Intended for healthy adults over 18.

Do not use if pregnant or nursing. Consult a doctor or medical authority before use if you have a medical condition, a family history of health problems, or if you take other medicines or supplements.

Do not exceed serving size. Stop use if you have a bad reaction. Contact your drug testing agency before use. Stop use after 8 weeks. Stop use 2 weeks before surgery. Do not combine with caffeine, stimulants, or alcohol. May cause a harmless tingling. Consumer accepts all liability if used inconsistent with label. 350mg of caffeine per serving.

California Prop 65 Warning: Lead- Cancer and Reproductive Harm www.P65Warnings.ca.gov

Allergen Warning: Produced in a facility that processes milk, eggs, soybeans, wheat, shellfish, fish, tree nuts, sesame, and peanuts.

Storage

Sold by weight, not volume. Store in a cool, dry place and do not discard desiccant.

FDA Disclaimer Statement

These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure or prevent any disease.

FDA Statement of Identity

Dietary Supplement

Is this label outdated? Report a formula or label change and our pharmacy team will review it.

See for yourself

Stimul8 Hardcore Grape Grenade by FINAFLEX label

The label scan from the NIH Dietary Supplement Label Database. Tap to enlarge.

Stimul8 Hardcore Grape Grenade label

Label images are published by the NIH Dietary Supplement Label Database for the version of this product on file. Always read your actual product label.

View the full label (PDF)
What’s inside

The Ingredients in Stimul8 Hardcore Grape Grenade by FINAFLEX

These are the 12 active ingredients this product is made of. Select any to open its full monograph.

Serving size8.75 Gram(s) Dosage formPowder Servings per container30 Amounts shown are per serving.

Most supplement products combine several ingredients, and a medication can interact with the product through any one of them. Each ingredient below shows whether it has known drug interactions.

Calcium

Interacts with
168 drugs
80 mg per serving

Calcium is an essential mineral your body needs for strong bones, nerve signaling, and muscle function, and supplements can help fill gaps when diet f...

Calcium monograph & interactions

L-Tyrosine

Interacts with
21 drugs
500 mg per serving

L-tyrosine is an amino acid your body uses to make brain chemicals like dopamine and norepinephrine. Some studies suggest it may help mental performan...

L-Tyrosine monograph & interactions

Beta-Alanine

No known
interactions
3200 mg per serving

Beta-alanine is an amino acid taken mostly by athletes to raise muscle carnosine, which may help buffer acid and reduce fatigue during short, high-int...

Beta-Alanine monograph & interactions

BioPerine

Interacts with
1,019 drugs
5 mg per serving

Black pepper is a common kitchen spice that is generally safe in the amounts used in food. Its extract, piperine, is mostly added to supplements to he...

BioPerine monograph & interactions

L-Theanine

Interacts with
565 drugs
150 mg per serving

Theanine (usually L-theanine) is an amino acid found naturally in tea leaves that many people take to feel calmer and less stressed without strong dro...

L-Theanine monograph & interactions

Citrulline Malate

6000 mg per serving

Agmatine Sulfate

Interacts with
258 drugs
750 mg per serving

Agmatine is a compound your body makes from the amino acid arginine, and it is sold mainly as a workout and 'pump' supplement. Human evidence for most...

Agmatine Sulfate monograph & interactions

Caffeine

Interacts with
655 drugs
350 mg per serving

Caffeine is a natural stimulant found in coffee, tea, and many other plants and products. In moderate amounts it can boost alertness and reduce tiredn...

Caffeine monograph & interactions

Alpha-Glycerylphosphorylcholine

Interacts with
16 drugs
300 mg per serving Form: L-Alpha-Glycerylphosphorylcholine

Alpha-GPC is a choline-containing compound used mainly for memory, brain health, and as a choline source. There is some evidence it may help cognition...

Alpha-Glycerylphosphorylcholine monograph & interactions

Betaine Anhydrous

No known
interactions
2500 mg per serving

Betaine anhydrous (also called trimethylglycine) is a compound found in foods like beets, spinach, and whole grains, and is sold as a supplement and a...

Betaine Anhydrous monograph & interactions

Citrus aurantium Extract

Interacts with
957 drugs
100 mg per serving

Bitter orange is a citrus fruit whose extracts contain synephrine, a mild stimulant often added to weight-loss and energy supplements. Evidence that i...

Citrus aurantium Extract monograph & interactions

Schisandra chinensis Berry Extract

Interacts with
803 drugs
150 mg per serving

Schisandra is a traditional Chinese medicine berry used as an adaptogen for stress, fatigue, and liver support. Human evidence is limited and most cla...

Schisandra chinensis Berry Extract monograph & interactions

Other (inactive) ingredients: Malic Acid, Natural & Artificial Flavors, Other Natural flavors, Citric Acid, Gum Arabic, Sucralose, Silica, Calcium Silicate, Potassium Citrate, Acesulfame Potassium. These complete the product’s ingredient list but are not active constituents.

Interaction report

Stimul8 Hardcore Grape Grenade by FINAFLEX Drug Interactions

Want to check YOUR meds against Stimul8 Hardcore Grape Grenade?

Ask about interactions with your drugs in plain English — “Can I take it with lisinopril?” — and we find you the answer in seconds, ingredient by ingredient.

 Go to the checker
1,494Drugs
25 Major 1,329 Moderate 140 Minor

Ingredients driving the most interactions

BioPerine 1,019
Citrus aurantium Extract 957
Schisandra chinensis Berry Extract 803
Caffeine 655
L-Theanine 565

Individual Drug Interactions

The ingredients in Stimul8 Hardcore Grape Grenade interact with 1,494 drugs. Click any drug to see the details.

9 of the 12 ingredients in Stimul8 Hardcore Grape Grenade interact with drugs. Each result below shows which ingredient is responsible. BioPerine Citrus aurantium Extract Schisandra chinensis Berry Extract Caffeine L-Theanine Agmatine Sulfate Calcium L-Tyrosine Alpha-Glycerylphosphorylcholine

Each ingredient & the kinds of drugs it affects

For each ingredient in Stimul8 Hardcore Grape Grenade with known interactions, here are the types of medications they can affect. Open any type for the detail — or search your exact drug in the checker above.

BioPerine17 drug types · 1,019 drugs

Anticoagulant/Antiplatelet Drugs

Theoretically, black pepper might increase the risk of bleeding when taken with antiplatelet or anticoagulant drugs.
In vitro research shows that piperine, a constituent of black pepper, seems to inhibit platelet aggregation. This has not been reported in humans.

Likelihood Possible Evidence D
Antidiabetes Drugs

Theoretically, black pepper might increase the risk of hypoglycemia when taken with antidiabetes drugs.
Animal research shows that piperine, a constituent of black pepper, can reduce blood glucose levels. Monitor blood glucose levels closely. Dose adjustments might be necessary.

Likelihood Possible Evidence D
Atorvastatin (Lipitor)

Theoretically, black pepper might increase blood levels of atorvastatin.
Animal research shows that taking piperine, a constituent of black pepper, 35 mg/kg can increase the maximum serum concentration of atorvastatin three-fold. This has not been reported in humans.

Likelihood Possible Evidence D
Cyclosporine (Neoral, Sandimmune)

Theoretically, black pepper might increase the effects and side effects of cyclosporine.
In vitro research shows that piperine, a constituent of black pepper, increases the bioavailability of cyclosporine. This has not been reported in humans.

Likelihood Possible Evidence D
Cytochrome P450 2D6 (Cyp2D6) Substrates

Theoretically, black pepper might increase levels of drugs metabolized by CYP2D6.
In vitro research suggests that some constituents of black pepper inhibit CYP2D6. This has not been reported in humans.

Likelihood Possible Evidence D
Cytochrome P450 3A4 (Cyp3A4) Substrates

Theoretically, black pepper might increase levels of drugs metabolized by CYP3A4.
In vitro research and pharmacokinetic simulation data suggest that piperine, a constituent of black pepper, as well as the pepper fruit seem to inhibit CYP3A4. This has not been reported in humans.

Likelihood Possible Evidence D
Lithium

Theoretically, black pepper might increase blood levels of lithium due to its diuretic effects. The dose of lithium might need to be reduced.
Black pepper is thought to have diuretic properties.

Likelihood Probable Evidence D
Nevirapine (Viramune)

Black pepper might increase blood levels of nevirapine.
Clinical research shows that piperine, a constituent of black pepper, increases the plasma concentration of nevirapine. However, no adverse effects were observed in this study.

Likelihood Probable Evidence D
P-Glycoprotein Substrates

Theoretically, black pepper might increase levels of P-glycoprotein substrates.
In vitro research shows that piperine, a constituent of black pepper, seems to inhibit P-glycoprotein.

Likelihood Possible Evidence D
Pentobarbital (Nembutal)

Theoretically, black pepper might increase the sedative effects of pentobarbital.
Animal research shows that piperine, a constituent of black pepper, increases pentobarbital-induced sleeping time.

Likelihood Possible Evidence D
Phenytoin (Dilantin)

Black pepper might increase blood levels of phenytoin.
Clinical research shows that piperine, a constituent of black pepper, seems to increase absorption, slow elimination, and increase levels of phenytoin. Taking a single dose of black pepper 1 gram along with phenytoin seems to double the serum concentration of phenytoin. Consuming a soup with black pepper providing piperine 44 mg/200 mL of soup along with phenytoin also seems to increase phenytoin levels when compared with consuming the same soup without black pepper.

Likelihood Possible Evidence B
Propranolol (Inderal)

Black pepper might increase blood levels of propranolol.
Clinical research shows that piperine, a constituent of black pepper, seems to increase absorption and slow elimination of propranolol.

Likelihood Possible Evidence B
Rifampin (Rifadin)

Black pepper might increase blood levels of rifampin.
Clinical research shows that piperine, a constituent of black pepper, seems to increase absorption and serum levels of rifampin.

Likelihood Possible Evidence B
Theophylline

Black pepper might increase blood levels of theophylline.
Clinical research shows that piperine, a constituent of black pepper, seems to increase absorption and slow elimination of theophylline.

Likelihood Possible Evidence D
Amoxicillin (Amoxil, Trimox)

Theoretically, black pepper might increase the effects and side effects of amoxicillin.
Animal research shows that taking piperine, a constituent of black pepper, with amoxicillin increases plasma levels of amoxicillin. This has not been reported in humans.

Likelihood Possible Evidence D
Carbamazepine (Tegretol)

Theoretically, black pepper might increase blood levels of carbamazepine, potentially increasing the effects and side effects of carbamazepine.
One clinical study in patients taking carbamazepine 300 mg or 500 mg twice daily shows that taking a single 20 mg dose of purified piperine, a constituent of black pepper, increases carbamazepine levels. Piperine may increase carbamazepine absorption by increasing blood flow to the GI tract, increasing the surface area of the small intestine, or inhibiting cytochrome P450 3A4 (CYP3A4) in the gut wall. Absorption was significantly increased by 7-10 mcg/mL/hour. The time to eliminate carbamazepine was also increased by 4-8 hours. Although carbamazepine levels were increased, this did not appear to increase side effects. In vitro research also shows that piperine can increase carbamazepine levels by 11% in a time-dependent manner.

Likelihood Possible Evidence B
Cytochrome P450 1A2 (Cyp1A2) Substrates

Theoretically, black pepper might decrease levels and clinical effects of drugs metabolized by CYP1A2.
In vitro research suggests that black pepper induces CYP1A2. This has not been reported in humans.

Likelihood Possible Evidence D
BioPerine full monograph & interactions

Citrus aurantium Extract13 drug types · 957 drugs

Midazolam (Versed)

Bitter orange might increase blood levels of midazolam.
One small clinical study shows that bitter orange juice can increase midazolam levels, likely through inhibition of cytochrome P450 3A4 (CYP3A4). Theoretically, bitter orange might increase the risk of midazolam-related adverse effects.

Likelihood Probable Evidence B
Monoamine Oxidase Inhibitors (Maois)

Theoretically, taking MAOIs with synephrine-containing bitter orange preparations might increase the hypertensive effects of synephrine, potentially leading to hypertensive crisis.
Bitter orange contains tyramine, octopamine, and synephrine, which are MAO substrates.

Likelihood Probable Evidence D
Antidiabetes Drugs

Theoretically, bitter orange might increase the risk of hypoglycemia when taken with antidiabetes drugs.
Some clinical research shows that drinking a tea containing bitter orange and Indian snakeroot reduces fasting and postprandial glucose levels in patients with type 2 diabetes who are using antidiabetes drugs. However, it is unclear if these effects are due to bitter orange, Indian snakeroot, or the combination. An animal study also shows that p-synephrine in combination with gliclazide , a sulfonylurea, causes an additional 20% to 44% decrease in glucose levels when compared with gliclazide alone.

Likelihood Possible Evidence B
Caffeine

Bitter orange might increase blood pressure and heart rate when taken with caffeine.
Small clinical studies show that taking bitter orange in combination with caffeine can increase blood pressure and heart rate in otherwise healthy normotensive adults. Theoretically, this might increase the risk of serious cardiovascular adverse effects.

Likelihood Possible Evidence B
Colchicine

Bitter orange might affect colchicine levels.
Colchicine is a substrate of P-glycoprotein and cytochrome P450 3A4 (CYP3A4). Bitter orange has been reported to inhibit CYP3A4 and increase levels of CYP3A4 substrates. However, one small clinical study in healthy adults shows that drinking bitter orange juice 240 mL twice daily for 4 days and taking a single dose of colchicine 0.6 mg on the 4th day decreases colchicine peak serum levels by 24%, time to peak serum level by 1 hour, and overall exposure to colchicine by 20%. The clinical significance of this finding is unclear.

Likelihood Possible Evidence B
Cytochrome P450 3A4 (Cyp3A4) Substrates

Bitter orange might increase levels of drugs metabolized by CYP3A4.
Small clinical studies suggest that single or multiple doses of freshly squeezed bitter orange juice 200-240 mL can inhibit CYP3A4 metabolism of drugs, causing increased drug levels and potentially increasing the risk of adverse effects. However, the extent of the effect of bitter orange on CYP3A4-mediated drug interactions is unknown. Some evidence suggests that bitter orange selectively inhibits intestinal CYP3A4, but not hepatic CYP3A4. Its effect on P-glycoprotein, which strongly overlaps with CYP3A4 interactions, is unclear. One small clinical study shows that drinking 8 ounces of freshly squeezed bitter orange juice has no effect on cyclosporine, which seems to be more dependent on hepatic CYP3A4 and P-glycoprotein than intestinal CYP3A4.

Likelihood Possible Evidence B
Dextromethorphan (Robitussin Dm, Others)

Bitter orange might increase blood levels of dextromethorphan.
One small clinical study shows that bitter orange juice increases dextromethorphan levels, likely through cytochrome P450 3A4 (CYP3A4) inhibition. Theoretically, bitter orange might increase the risk for dextromethorphan-related adverse effects.

Likelihood Possible Evidence B
Felodipine (Plendil)

Bitter orange might increase blood levels of felodipine.
One small clinical study shows that bitter orange juice increases felodipine levels, likely through cytochrome P450 3A4 (CYP3A4) inhibition. Theoretically, bitter orange might increase the risk for felodipine-related adverse effects.

Likelihood Probable Evidence B
Indinavir (Crixivan)

Bitter orange might increase blood levels of indinavir.
One small clinical study shows that bitter orange juice slightly increases indinavir levels, but this effect is likely to be clinically insignificant. Bitter orange selectively inhibits intestinal cytochrome P450 3A4 (CYP3A4); however, the metabolism of indinavir seems to be more dependent on hepatic CYP3A4. The effect of bitter orange on other protease inhibitors has not been studied.

Likelihood Possible Evidence B
Qt Interval-Prolonging Drugs

Theoretically, bitter orange might have an additive effect when combined with drugs that prolong the QT interval, potentially increasing the risk of ventricular arrhythmias.
One case report suggests that taking bitter orange in combination with other stimulants such as caffeine might prolong the QT interval in some patients.

Likelihood Possible Evidence D
Sildenafil (Viagra)

Bitter orange juice might increase blood levels of sildenafil.
A small clinical study in healthy adult males shows that drinking freshly squeezed bitter orange juice 250 mL daily for 3 days and taking a single dose of sildenafil 50 mg on the 3rd day increases the peak plasma concentration of sildenafil by 18% and the overall exposure to sildenafil by 44%. Theoretically, this may be due to inhibition of cytochrome P450 3A4 by bitter orange.

Likelihood Probable Evidence B
Stimulant Drugs

Theoretically, bitter orange might increase the risk of hypertension and adverse cardiovascular effects when taken with stimulant drugs.
Bitter orange appears to have stimulant effects.

Likelihood Possible Evidence B
Cytochrome P450 2D6 (Cyp2D6) Substrates

Theoretically, bitter orange might increase levels of drug metabolized by CYP2D6.
In vitro research shows that octopamine, a constituent of bitter orange, weakly inhibits CYP2D6 enzymes. This effect has not been reported in humans.

Likelihood Possible Evidence D
Citrus aurantium Extract full monograph & interactions

Schisandra chinensis Berry Extract12 drug types · 803 drugs

Cyclophosphamide

Theoretically, schisandra might increase the levels and clinical effects of cyclophosphamide.
In vitro research shows that schisandra increases the concentration of cyclophosphamide, likely through inhibition of cytochrome P450 3A4. After multiple doses of the schisandra constituents schisandrin A and schisantherin A, the maximum concentration of cyclophosphamide was increased by 7% and 75%, respectively, while the overall exposure to cyclophosphamide was increased by 29% and 301%, respectively.

Likelihood Probable Evidence D
Cyclosporine (Neoral, Sandimmune)

Schisandra can increase the levels and clinical effects of cyclosporine.
A small observational study in children with aplastic anemia found that taking schisandra with cyclosporine increased cyclosporine trough levels by 93% without increasing the risk of adverse events. However, the dose of cyclosporine was reduced in 9% of children to maintain appropriate cyclosporine blood concentrations.

Likelihood Probable Evidence B
Cytochrome P450 2C19 (Cyp2C19) Substrates

Theoretically, schisandra might increase the levels and clinical effects of CYP2C19 substrates.
In vitro research shows that schisandra inhibits CYP2C19, and animal research shows that schisandra increases the concentration of voriconazole, a CYP2C19 substrate. Theoretically, schisandra may also inhibit the metabolism of other CYP2C19 substrates. This effect has not been reported in humans.

Likelihood Probable Evidence D
Cytochrome P450 2C9 (Cyp2C9) Substrates

Theoretically, schisandra might decrease the levels and clinical effects of CYP2C9 substrates.
In vitro and animal research suggests that schisandra induces CYP2C9 enzymes. This effect has not been reported in humans.

Likelihood Possible Evidence D
Cytochrome P450 3A4 (Cyp3A4) Substrates

Schisandra can increase the levels and clinical effects of drugs metabolized by CYP3A4.
Most clinical and laboratory research shows that schisandra, administered either as a single dose or up to twice daily for 14 days, inhibits CYP3A4 and increases the concentration of CYP3A4 substrates such as cyclophosphamide, midazolam, tacrolimus, and talinolol. Although one in vitro and animal study shows that schisandra may induce CYP3A4 metabolism, this effect appears to be overpowered by schisandra's CYP3A4 inhibitory activity and has not been reported in humans.

Likelihood Probable Evidence D
Midazolam (Versed)

Schisandra can increase the levels and clinical effects of midazolam.
A small pharmacokinetic study in healthy adults shows that taking schisandra extract (Hezheng Pharmaceutical Co.) containing deoxyschizandrin 33.75 mg twice daily for 8 days and a single dose of midazolam 15 mg on day 8 increases the overall exposure to midazolam by about 119%, increases the peak plasma level of midazolam by 86%, and decreases midazolam clearance by about 52%. This effect has been attributed to inhibition of CYP3A4 by schisandra.

Likelihood Probable Evidence B
P-Glycoprotein Substrates

Schisandra might increase the levels and clinical effects of P-glycoprotein substrates.
In vitro research shows that schisandra extracts and constituents such as schisandrin B inhibit P-glycoprotein mediated efflux in intestinal cells and in P-glycoprotein over-expressing cell lines. Additionally, a small clinical study shows that schisandra increases the peak concentration and overall exposure to talinolol, a P-glycoprotein probe substrate. Theoretically, schisandra might inhibit the efflux of other P-glycoprotein substrates.

Likelihood Possible Evidence D
Sirolimus (Rapamune)

Schisandra can increase the levels and clinical effects of sirolimus.
A small pharmacokinetic study in healthy volunteers shows that taking 3 capsules of schisandra (Hezheng Pharmaceutical Company) containing a total of 33.75 mg deoxyschizandrin twice daily for 13 days and then taking a single dose of sirolimus 2 mg increases the overall exposure and peak level of sirolimus by two-fold. This effect is thought to be due to inhibition of cytochrome P450 3A4 by schisandra, as well as possible inhibition of the P-glycoprotein drug transporter.

Likelihood Probable Evidence B
Tacrolimus (Prograf)

Schisandra can increase the levels and clinical effects of tacrolimus.
Clinical research in healthy children and adults, transplant patients, and patients with nephrotic syndrome and various rheumatic immunologic disorders shows that taking schisandra with tacrolimus increases tacrolimus peak levels by 183% to 268%, prolongs or delays time to peak tacrolimus concentrations, increases overall exposure to tacrolimus by 126% to 343%, and decreases tacrolimus clearance by 19% to 73%. This effect is thought to be due to inhibition of P-glycoprotein drug transporter and CYP3A4 and CYP3A5 by schisandra. Some clinical and observational studies suggest that schisandra increases tacrolimus levels similarly in both expressors and non-expressors of CYP3A5, while other studies suggest it does so to a greater degree in CYP3A5 expressors than non-expressors. Animal research suggests that the greatest increase in tacrolimus levels occurs when schisandra is taken either concomitantly or up to 2 hours before tacrolimus, and clinical and observational research in humans suggests that schisandra may increase whole blood levels of tacrolimus and decrease clearance of tacrolimus in a dose-dependent manner.

Likelihood Probable Evidence B
Talinolol

Schisandra can increase the levels and clinical effects of talinolol.
A small pharmacokinetic study in healthy volunteers shows that taking schisandra extract 300 mg twice daily for 14 days with a single dose of talinolol 100 mg on day 14 increases the peak talinolol level by 51% and the overall exposure to talinolol by 47%. This effect is thought to be due to the possible inhibition of cytochrome P450 3A4 and P-glycoprotein by schisandra. tly.

Likelihood Probable Evidence B
Voriconazole (Vfend)

Theoretically, schisandra might increase the levels and clinical effects of voriconazole.
Animal research shows that oral schisandra given daily for 1 or 14 days increases levels of intravenously administered voriconazole, a cytochrome P450 (CYP) 2C19 substrate. This effect is thought to be due to inhibition of CYP2C19 by schisandra. However, this interaction has not been reported in humans.

Likelihood Possible Evidence D
Warfarin (Coumadin)

Theoretically, schisandra might decrease the levels and clinical effects of warfarin.
Animal research suggests that oral schisandra extract, given daily for 6 days, reduces levels of intravenously administered warfarin. This effect might be due to the induction of cytochrome P450 (CYP) 2C9 metabolism by schisandra. However, this interaction has not been reported in humans.

Likelihood Possible Evidence D
Schisandra chinensis Berry Extract full monograph & interactions

Caffeine41 drug types · 655 drugs

Ephedrine

Theoretically, concomitant use might increase the risk for stimulant adverse effects.
Use of ephedrine with caffeine can increase the risk of stimulatory adverse effects. There is evidence that using ephedrine with caffeine might increase the risk of serious life-threatening or debilitating adverse effects such as hypertension, myocardial infarction, stroke, seizures, and death.

Likelihood Probable Evidence D
Adenosine (Adenocard)

Theoretically, caffeine might decrease the vasodilatory effects of adenosine and interfere with its use prior to stress testing.
Some evidence shows that caffeine is a competitive inhibitor of adenosine and can reduce the vasodilatory effects of adenosine in humans. However, other research shows that caffeine does not seem to affect supplemental adenosine because high interstitial levels of adenosine overcome the antagonistic effects of caffeine. It is recommended that methylxanthines and methylxanthine-containing products be stopped 24 hours prior to pharmacological stress tests. However, methylxanthines appear more likely to interfere with dipyridamole (Persantine) than adenosine-induced stress testing.

Likelihood Possible Evidence B
Anticoagulant/Antiplatelet Drugs

Theoretically, caffeine may increase the risk of bleeding if used with anticoagulant or antiplatelet drugs.
Caffeine is reported to have antiplatelet activity. Theoretically, it might increase the risk of bleeding when used concomitantly with these agents; however, this interaction has not been reported in humans.

Likelihood Possible Evidence D
Beta-Adrenergic Agonists

Theoretically, large amounts of caffeine might increase the cardiac inotropic effects of beta-agonists.

Likelihood Probable Evidence D
Carbamazepine (Tegretol)

Theoretically, caffeine might reduce the effects of carbamazepine and increase the risk for convulsions.
Animal research suggests that taking caffeine can lower the anticonvulsant effects of carbamazepine and can induce seizures when taken in doses above 400 mg/kg. Human research has shown that taking caffeine 300 mg in three divided doses along with carbamazepine 200 mg reduces the bioavailability of carbamazepine by 32% and prolongs the plasma half-life of carbamazepine 2-fold in healthy individuals.

Likelihood Possible Evidence D
Cimetidine (Tagamet)

Theoretically, cimetidine might increase the levels and adverse effects of caffeine.
Cimetidine decreases the rate of caffeine clearance by 31% to 42%.

Likelihood Likely Evidence B
Clozapine (Clozaril)

Caffeine might increase the levels and adverse effects of clozapine and acutely exacerbate psychotic symptoms.
Caffeine might increase the effects and toxicity of clozapine. Caffeine doses of 400-1000 mg per day inhibit clozapine metabolism. Clozapine is metabolized by cytochrome P450 1A2 (CYP1A2). Although researchers speculate that caffeine might inhibit CYP1A2, there is no reliable evidence that caffeine affects CYP1A2. There is also speculation that genetic factors might make some patients more sensitive to an interaction between clozapine and caffeine. In one case report, severe, life-threatening clozapine toxicity and multiorgan system failure occurred in a patient with schizophrenia stabilized on clozapine who consumed caffeine 600 mg daily.

Likelihood Possible Evidence B
Dipyridamole (Persantine)

Theoretically, caffeine might decrease the vasodilatory effects of dipyridamole and interfere with its use prior to stress testing.
Caffeine inhibits dipyridamole-induced vasodilation. It is recommended that methylxanthines and methylxanthine-containing products be stopped 24 hours prior to pharmacological stress tests. Methylxanthines appear more likely to interfere with dipyridamole (Persantine) than adenosine-induced stress testing.

Likelihood Probable Evidence B
Disulfiram (Antabuse)

Theoretically, disulfiram use might increase the levels and adverse effects of caffeine.
Disulfiram decreases the rate of caffeine clearance.

Likelihood Probable Evidence B
Diuretic Drugs

Theoretically, using caffeine with diuretic drugs might increase the risk of hypokalemia.
Caffeine, especially in excessive amounts, can reduce potassium levels due to stimulation of the sodium-potassium pump. Diuretics can also cause lower potassium levels.

Likelihood Possible Evidence D
Estrogens

Theoretically, estrogens might increase the levels and adverse effects of caffeine.
Estrogen inhibits caffeine metabolism.

Likelihood Probable Evidence B
Ethosuximide (Zarontin)

Theoretically, caffeine might reduce the effects of ethosuximide and increase the risk for convulsions.
Animal research suggests that caffeine 92.4 mg/kg can decrease the anticonvulsant activity of ethosuximide. However, this effect has not been reported in humans.

Likelihood Possible Evidence D
Felbamate (Felbatol)

Theoretically, caffeine might reduce the effects of felbamate and increase the risk for convulsions.
Animal research suggests that a high dose of caffeine 161.7 mg/kg can decreases the anticonvulsant activity of felbamate. However, this effect has not been reported in humans.

Likelihood Possible Evidence D
Flutamide (Eulexin)

Theoretically, caffeine might increase the levels and adverse effects of flutamide.
In vitro evidence suggests that caffeine can inhibit the metabolism of flutamide. However, this effect has not been reported in humans.

Likelihood Probable Evidence D
Fluvoxamine (Luvox)

Theoretically, fluvoxamine might increase the levels and adverse effects of caffeine.
Fluvoxamine reduces caffeine metabolism.

Likelihood Probable Evidence D
Lithium

Abrupt caffeine withdrawal might increase the levels and adverse effects of lithium.
Caffeine has diuretic activity. When abruptly discontinued, caffeine may alter the clearance of lithium. There are two case reports of lithium tremor that worsened upon abrupt coffee withdrawal and 6 case reports of elevated serum lithium levels after reducing or eliminating caffeine intake. In one case, a male with schizoaffective disorder stabilized on lithium had an elevated lithium level after reducing his caffeine intake by 87%. At a later date, he increased his caffeine intake by 6-fold, resulting in a subtherapeutic lithium level and a recurrence of psychiatric symptoms.

Likelihood Probable Evidence D
Monoamine Oxidase Inhibitors (Maois)

Theoretically, concomitant use might increase the risk of a hypertensive crisis.
Caffeine has been shown to inhibit monoamine oxidase (MAO) A and B in laboratory studies. Concomitant intake of large amounts of caffeine with MAOIs might precipitate a hypertensive crisis. In a case report, a patient that consumed 10-12 cups of caffeinated coffee and took the MAOI tranylcypromine presented with severe hypertension. Hypertension was resolved after the patient switched to drinking decaffeinated coffee.

Likelihood Possible Evidence D
Nicotine

Theoretically, concomitant use might increase the risk of hypertension.
Concomitant use of caffeine and nicotine has been shown to have additive cardiovascular effects, including increased heart rate and blood pressure. Blood pressure was increased by 10.8/12.4 mmHg when the agents were used concomitantly.

Likelihood Probable Evidence B
Pentobarbital (Nembutal)

Theoretically, caffeine might decrease the effects of pentobarbital.
Caffeine might negate the hypnotic effects of pentobarbital.

Likelihood Possible Evidence B
Phenobarbital (Luminal)

Theoretically, caffeine might reduce the effects of phenobarbital and increase the risk for convulsions.
Animal research suggests that caffeine can decrease the anticonvulsant activity of phenobarbital. However, the exact mechanism of this interaction is unclear.

Likelihood Possible Evidence D
Phenylpropanolamine

Theoretically, phenylpropanolamine might increase the risk of hypertension, as well as the levels and adverse effects of caffeine.
Concomitant use of phenylpropanolamine and caffeine might cause an additive increase in blood pressure. Phenylpropanolamine also seems to increase caffeine serum levels.

Likelihood Probable Evidence B
Phenytoin (Dilantin)

Theoretically, caffeine might reduce the effects of phenytoin and increase the risk for convulsions.
Animal research suggests that caffeine can decrease the anticonvulsant activity of phenytoin. The effect does not seem to be related to the seizure threshold-lowering effects of caffeine. However, the exact mechanism of this interaction is unclear.

Likelihood Possible Evidence D
Pioglitazone (Actos)

Theoretically, caffeine might increase the levels and clinical effects of pioglitazone.
Animal research suggests that caffeine can modestly increase the maximum concentration, area under the curve, and half-life of pioglitazone, and also reduce its clearance. This increased the antidiabetic effects of pioglitazone. However, the exact mechanism of this interaction is unclear.

Likelihood Possible Evidence D
Quinolone Antibiotics

Theoretically, quinolone antibiotics might increase the levels and adverse effects of caffeine.
Quinolones (also called fluoroquinolones) can decrease caffeine clearance by inhibiting cytochrome P450 1A2 (CYP1A2) enzyme.

Likelihood Probable Evidence B
Riluzole (Rilutek)

Theoretically, concomitant use might increase the levels and adverse effects of both caffeine and riluzole.
Caffeine and riluzole are both metabolized by cytochrome P450 1A2 (CYP1A2), and concomitant use might reduce the metabolism of one or both agents.

Likelihood Possible Evidence D
Caffeine full monograph & all 41 interactions

L-Theanine3 drug types · 565 drugs

Antihypertensive Drugs

Theanine might lower blood pressure, potentiating the effects of antihypertensive drugs.
Animal research shows that theanine can lower blood pressure in spontaneously hypertensive animals. Theoretically, concomitant use of theanine and antihypertensive drugs might potentiate the antihypertensive activity.

Likelihood Possible Evidence D
Cns Depressants

Theoretically, theanine might have additive sedative effects when used in conjunction with CNS depressants. However, it is unclear if this concern is clinically relevant.
Theoretically, theanine may compete with glutamate and/or increase plasma gamma-aminobutyric acid (GABA) levels, which could cause CNS depression. In one clinical study, some subjects taking oral theanine reported drowsiness.

Likelihood Unlikely Evidence D
Serotonergic Drugs

Clinical studies regarding the effects of L-theanine on serotonin levels are conflicting. Some studies suggest it can increase serotonin levels in the brain while others report that it may decrease them. Nevertheless, there have been no reports of l-theanine being a causative agent in serotonergic-related side effects or serotonin syndrome.

Likelihood Unlikely Evidence C
L-Theanine full monograph & interactions

Agmatine Sulfate2 drug types · 258 drugs

Antidiabetes Drugs

Theoretically, agmatine might increase the risk of hypoglycemia when taken with antidiabetes drugs.
Animal and in vitro research suggest that agmatine has mild hypoglycemic effects.

Likelihood Possible Evidence D
Antihypertensive Drugs

Theoretically, agmatine might increase the risk of hypotension when taken with antihypertensive drugs.
Animal research suggests that agmatine can modestly decrease heart rate and blood pressure.

Likelihood Possible Evidence D
Agmatine Sulfate full monograph & interactions

Calcium18 drug types · 168 drugs

Ceftriaxone (Rocephin)

Co-administration of intravenous calcium and ceftriaxone can result in precipitation of a ceftriaxone-calcium salt in the lungs and kidneys.
Avoid administering intravenous calcium in any form, such as parenteral nutrition or Lactated Ringers, within 48 hours of intravenous ceftriaxone. Case reports in neonates show that administering intravenous ceftriaxone and calcium can result in precipitation of a ceftriaxone-calcium salt in the lungs and kidneys. In several cases, neonates have died as a result of this interaction. So far there are no reports in adults; however, there is still concern that this interaction might occur in adults.

Likelihood Probable Evidence D
Dolutegravir (Tivicay)

Calcium seems to reduce levels of dolutegravir.
Advise patients to take dolutegravir either 2 hours before or 6 hours after taking calcium supplements. Pharmacokinetic research suggests that taking calcium carbonate 1200 mg concomitantly with dolutegravir 50 mg reduces plasma levels of dolutegravir by almost 40%. Calcium appears to decrease levels of dolutegravir through chelation.

Likelihood Probable Evidence B
Elvitegravir (Vitekta)

Calcium seems to reduce levels of elvitegravir.
Advise patients to take elvitegravir either 2 hours before or 2 hours after taking calcium supplements. Pharmacokinetic research suggests that taking calcium along with elvitegravir can reduce blood levels of elvitegravir through chelation.

Likelihood Probable Evidence B
Aluminum

Calcium citrate might increase aluminum absorption and toxicity. Other types of calcium do not increase aluminum absorption.
Calcium citrate can increase the absorption of aluminum when taken with aluminum hydroxide. The increase in aluminum levels may become toxic, particularly in individuals with kidney disease. However, the effect of calcium citrate on aluminum absorption is due to the citrate anion rather than calcium cation. Calcium acetate does not appear to increase aluminum absorption.

Likelihood Possible Evidence B
Bictegravir/Emtricitabine/Tenofovir Alafenamide (Biktarvy)

Calcium might decrease levels of bictegravir/emtricitabine/tenofovir alafenamide by reducing its absorption when taken in a fasting state.
Advise patients that bictegravir/emtricitabine/tenofovir alafenamide and calcium can be taken together if taken with food. However, if taken on an empty stomach, bictegravir/emtricitabine/tenofovir alafenamide should not be taken with, or 2 hours after, calcium containing products.

Likelihood Probable Evidence D
Bisphosphonates

Calcium reduces the absorption of bisphosphonates.
Advise patients to take bisphosphonates at least 30 minutes before calcium, but preferably at a different time of day. Calcium supplements decrease absorption of bisphosphonates.

Likelihood Probable Evidence C
Calcipotriene (Dovonex)

Taking calcipotriene with calcium might increase the risk for hypercalcemia.
Calcipotriene is a vitamin D analog used topically for psoriasis. It can be absorbed in sufficient amounts to cause systemic effects, including hypercalcemia. Theoretically, combining calcipotriene with calcium supplements might increase the risk of hypercalcemia.

Likelihood Possible Evidence B
Digoxin (Lanoxin)

Using intravenous calcium with digoxin might increase the risk of fatal cardiac arrhythmias.
Hypercalcemia increases the risk of fatal cardiac arrhythmias with digoxin. However, one retrospective analysis of clinical data suggests that intravenous calcium does not increase the risk of dysrhythmias or mortality in patients receiving digoxin.

Likelihood Possible Evidence B
Diltiazem (Cardizem, Others)

Theoretically, calcium may reduce the therapeutic effects of diltiazem.
Hypercalcemia can reduce the effectiveness of verapamil in atrial fibrillation. Theoretically, calcium might increase this risk of hypercalcemia and reduce the effectiveness of diltiazem.

Likelihood Probable Evidence D
Levothyroxine (Synthroid, Others)

Calcium seems to reduce the absorption and effectiveness of levothyroxine.
Advise patients to take levothyroxine and calcium supplements at least 4 hours apart. Calcium reduces levothyroxine absorption, probably by forming insoluble complexes. Calcium carbonate supplements reduce effectiveness of levothyroxine in patients with hypothyroidism.

Likelihood Probable Evidence B
Lithium

Theoretically, concomitant use of calcium and lithium may increase this risk of hypercalcemia.
Clinical research suggests that long-term use of lithium may cause hypercalcemia in 10% to 60% of patients. Theoretically, concomitant use of lithium and calcium supplements may further increase this risk.

Likelihood Possible Evidence B
Quinolone Antibiotics

Calcium seems to reduce the absorption of quinolone antibiotics.
Advise patients to take oral quinolones at least 2 hours before or 4-6 hours after calcium supplements or calcium-fortified foods. Taking calcium at the same time as oral quinolones can reduce quinolone absorption. Calcium binds to quinolones in the gut.

Likelihood Probable Evidence B
Raltegravir (Isentress)

Calcium may reduce levels of raltegravir.
Pharmacokinetic research shows that taking a single dose of calcium carbonate 3000 mg along with raltegravir 400 mg twice daily modestly decreases the mean area under the curve of raltegravir, but the decrease does not necessitate a dose adjustment of raltegravir. However, a case of elevated HIV-1 RNA levels and documented resistance to raltegravir has been reported for a patient taking calcium carbonate 1 gram three times daily plus vitamin D3 (cholecalciferol) 400 IU three times daily in combination with raltegravir 400 mg twice daily for 11 months. It is thought that calcium reduced raltegravir levels by chelation, leading to treatment failure.

Likelihood Possible Evidence B
Sotalol (Betapace)

Calcium seems to reduce the absorption of sotalol.
Advise patients to separate doses by at least 2 hours before or 4-6 hours after calcium. Calcium appears to reduce the absorption of sotalol, probably by forming insoluble complexes.

Likelihood Possible Evidence B
Tetracycline Antibiotics

Calcium seems to reduce the absorption of tetracycline antibiotics.
Advise patients to take oral tetracyclines at least 2 hours before, or 4-6 hours after calcium supplements. Taking calcium at the same time as oral tetracyclines can reduce tetracycline absorption. Calcium binds to tetracyclines in the gut.

Likelihood Probable Evidence C
Thiazide Diuretics

Taking calcium along with thiazides might increase the risk of hypercalcemia and renal failure.
Thiazides reduce calcium excretion by the kidneys. Using thiazides along with moderately large amounts of calcium carbonate increases the risk of milk-alkali syndrome (hypercalcemia, metabolic alkalosis, renal failure). Patients may need to have their serum calcium levels and/or parathyroid function monitored regularly.

Likelihood Probable Evidence C
Verapamil (Calan, Others)

Theoretically, calcium may reduce the therapeutic effects of verapamil.
Hypercalcemia can reduce the effectiveness of verapamil in atrial fibrillation. Theoretically, use of calcium supplements may increase this risk of hypercalcemia and reduce the effectiveness of verapamil.

Likelihood Probable Evidence D
Calcium Channel Blockers

Intravenous calcium may decrease the effects of calcium channel blockers; oral calcium is unlikely to have this effect.
Intravenous calcium is used to decrease the effects of calcium channel blockers in the management of overdose. Intravenous calcium gluconate has been used before intravenous verapamil (Isoptin) to prevent or reduce the hypotensive effects without affecting the antiarrhythmic effects. But there is no evidence that dietary or supplemental calcium when taken orally interacts with calcium channel blockers.

Likelihood Unlikely Evidence D
Calcium full monograph & interactions

L-Tyrosine2 drug types · 21 drugs

Levodopa

Theoretically, tyrosine might decrease the effectiveness of levodopa.
Tyrosine and levodopa compete for absorption in the proximal duodenum by the large neutral amino acid (LNAA) transport system. Advise patients to separate doses of tyrosine and levodopa by at least 2 hours.

Likelihood Probable Evidence D
Thyroid Hormone

Theoretically, tyrosine might have additive effects with thyroid hormone medications.
Tyrosine is a precursor to thyroxine and might increase levels of thyroid hormones.

Likelihood Probable Evidence D
L-Tyrosine full monograph & interactions

Alpha-Glycerylphosphorylcholine1 drug type · 16 drugs

Scopolamine (Transderm Scop)

Theoretically, alpha-GPC might decrease the effects of scopolamine.
A small clinical study shows that alpha-GPC can partially counteract the attention and memory impairment effects caused by scopolamine given intramuscularly. Whether alpha-GPC can decrease the beneficial anti-motion sickness effects of the scopolamine patch (Transderm Scop) is unclear.

Likelihood Possible Evidence B
Alpha-Glycerylphosphorylcholine full monograph & interactions
The maker

Brand information

Manufacturer and brand details for Stimul8 Hardcore Grape Grenade, from the product label.

FINAFLEX

See all FINAFLEX products
Name
FINAFLEX
Street Address
3615 Francis Cir Suite 100
City
Alpharetta
State
GA
ZipCode
30004
Phone Number
888.678.7629
Web Address
www.FINAFLEX.com
Pharmacist Counseling Corner

Stimul8 Hardcore Grape Grenade by FINAFLEX: Common Questions

Does Stimul8 Hardcore Grape Grenade by FINAFLEX interact with any medications?
Yes. Based on its ingredients, Stimul8 Hardcore Grape Grenade has a known interaction with 1,494 medications, including 25 rated major. Use the checker to see how it interacts with a specific drug.
How can one product interact with so many drugs?
Stimul8 Hardcore Grape Grenade contains 12 active ingredients, and an interaction can come from any of them. We check every ingredient, combine the results into one list per medication, and show which ingredient and mechanism is responsible.
Where does this information come from?
The product label data comes from the NIH Dietary Supplement Label Database (DSLD); the interaction data is built on the Natural Medicines database and reviewed by HelloPharmacist pharmacists.
What does L-Theanine do in this formula?
L-Theanine is an amino acid that's possibly effective for supporting cognitive function. It may help with mental focus during or before a workout. Some people find it helps them stay calm and alert at the same time.
Why does Beta-Alanine make my skin tingle?
That tingling (paresthesia) is a harmless side effect from beta-alanine. It typically starts on your scalp within 20 minutes of taking the supplement and spreads to other parts of your body, lasting about an hour. The tingling is more noticeable at higher doses and affects fewer people at lower doses.
Can I take this if I'm on blood pressure medication?
Not without checking first. L-Theanine, Agmatine, and Bitter Orange can all lower blood pressure, which could cause too much of a drop if you're already on blood pressure meds. Use the medication checker on this page with your exact drug name, and talk to your pharmacist before starting.
Is this safe to take with other supplements or energy drinks?
No. This product contains caffeine and bitter orange, both of which raise heart rate and blood pressure. Combining it with other caffeinated products, energy drinks, or stimulant supplements significantly increases your risk of serious heart problems. Stick to this product alone.
What's BioPerine, and why is it in here?
BioPerine is a concentrated black pepper extract. It's included to help your body absorb and use the other ingredients more effectively. However, it can increase blood levels of several medications, so it's important to check any prescriptions you take.
Can I take this while pregnant or breastfeeding?
You should talk to your doctor or pharmacist before using this product during pregnancy or while breastfeeding. Several ingredients—including Beta-Alanine, L-Theanine, Agmatine, and Bitter Orange—don't have enough safety data in pregnancy and lactation, and your provider needs to weigh the risks and benefits for your situation.

Written and reviewed by the HelloPharmacist editorial staff. Our editorial policy

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Stimul8 Hardcore Grape Grenade label
Go deeper

The Full Monographs Behind Stimul8 Hardcore Grape Grenade’s Ingredients

Every ingredient we hold a full HelloPharmacist monograph for — uses, evidence, safety, and the complete interaction list.

Herb & supplement monograph

Calcium

Interacts with 168 drugs

Calcium is an essential mineral your body needs for strong bones, nerve signaling, and muscle function, and supplements can help fill gaps when diet falls short. Most people do best getting...

Read the full Calcium monograph → Herb & supplement monograph

Tyrosine

Interacts with 21 drugs

L-tyrosine is an amino acid your body uses to make brain chemicals like dopamine and norepinephrine. Some studies suggest it may help mental performance during short-term stress, sleep loss,...

Read the full Tyrosine monograph → Herb & supplement monograph

Beta-alanine

Beta-alanine is an amino acid taken mostly by athletes to raise muscle carnosine, which may help buffer acid and reduce fatigue during short, high-intensity exercise. The evidence is moderat...

Read the full Beta-alanine monograph → Herb & supplement monograph

Black Pepper

Interacts with 1,019 drugs

Black pepper is a common kitchen spice that is generally safe in the amounts used in food. Its extract, piperine, is mostly added to supplements to help the body absorb other ingredients (li...

Read the full Black Pepper monograph → Herb & supplement monograph

Theanine

Interacts with 565 drugs

Theanine (usually L-theanine) is an amino acid found naturally in tea leaves that many people take to feel calmer and less stressed without strong drowsiness. Early research suggests it may...

Read the full Theanine monograph → Herb & supplement monograph

Agmatine

Interacts with 258 drugs

Agmatine is a compound your body makes from the amino acid arginine, and it is sold mainly as a workout and 'pump' supplement. Human evidence for most of its claimed benefits is limited and...

Read the full Agmatine monograph → Herb & supplement monograph

Caffeine

Interacts with 655 drugs

Caffeine is a natural stimulant found in coffee, tea, and many other plants and products. In moderate amounts it can boost alertness and reduce tiredness for most healthy adults, but too muc...

Read the full Caffeine monograph → Herb & supplement monograph

Alpha-gpc

Interacts with 16 drugs

Alpha-GPC is a choline-containing compound used mainly for memory, brain health, and as a choline source. There is some evidence it may help cognition in people with dementia, but evidence i...

Read the full Alpha-gpc monograph → Herb & supplement monograph

Betaine Anhydrous

Betaine anhydrous (also called trimethylglycine) is a compound found in foods like beets, spinach, and whole grains, and is sold as a supplement and as a prescription medicine for a rare gen...

Read the full Betaine Anhydrous monograph → Herb & supplement monograph

Bitter Orange

Interacts with 957 drugs

Bitter orange is a citrus fruit whose extracts contain synephrine, a mild stimulant often added to weight-loss and energy supplements. Evidence that it works for weight loss or performance i...

Read the full Bitter Orange monograph → Herb & supplement monograph

Schisandra

Interacts with 803 drugs

Schisandra is a traditional Chinese medicine berry used as an adaptogen for stress, fatigue, and liver support. Human evidence is limited and most claims are not well proven, but it appears...

Read the full Schisandra monograph →
Sources

Sources & How We Checked

Stimul8 Hardcore Grape Grenade's label data comes from the NIH Dietary Supplement Label Database; the ingredient interaction data is from the Natural Medicines database, reviewed by our pharmacists.

Content is written and reviewed by licensed HelloPharmacist pharmacists. See our data sources and editorial standards for how this information is built and checked.

The 441 references behind this product’s interaction data

Every citation that drives the interaction findings for this product’s ingredients, from the evidence-graded Natural Medicines (TRC Healthcare) database. Open an ingredient to browse its citations — links open the study on PubMed or the publisher’s site.

Calcium 62 references
  1. Shils M, Olson A, Shike M. Modern Nutrition in Health and Disease. 8th ed. Philadelphia, PA: Lea and Febiger, 1994.
  2. Hernandez-Avila M, Gonzalez-Cossio T, Hernandez-Avila JE, et al. Dietary calcium supplements to lower blood lead levels in lactating women: a randomized placebo-controlled trial. Epidemiology 2003;14:206-12.. PubMed
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See these in context on the Bitter Orange monograph →

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See these in context on the Schisandra monograph →

Parts of this content are provided by the Therapeutic Research Center, LLC.

DISCLAIMER: Currently this does not check for drug-drug interactions. This is not an all-inclusive comprehensive list of potential interactions and is for informational purposes only. Not all interactions are known or well-reported in the scientific literature, and new interactions are continually being reported. Input is needed from a qualified healthcare provider including a pharmacist before starting any therapy. Application of clinical judgment is necessary.

© 2021 Therapeutic Research Center, LLC

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