Major interaction on record — check this product against your medications before combining. Based on 4 of 6 ingredients. Check your meds →
Dietary supplement

Spirodex Ingredients & Drug Interactions

by Gaspari Nutrition

Spirodex label
See full label image
Tablet Or Pill Category: Other Combinations
Most serious interaction: Major
Clinical methodology reviewed by · Updated Sep 9, 2026 · Label data from the NIH DSLD
What is this page for?

First and foremost: checking Spirodex 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

Spirodex is a dietary supplement by Gaspari Nutrition with 6 active ingredients. Its ingredients are commonly taken for mental alertness and reducing fatigue, improving athletic performance, headache and migraine relief.Based on those ingredients, 807 medications have a known interaction with it, the most serious rated major. The ingredients most likely to interact are Camellia sinensis, Caffeine, Paullinia cupana [whole plant] extract. Use the checker below to test your specific medication, or read the full HelloPharmacist Interaction Report.

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Check Your Meds Against Spirodex by Gaspari Nutrition

Ask about any prescription or over-the-counter medication and we check it for interactions with Spirodex by Gaspari Nutrition — and tell you which ingredient is responsible.

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HelloPharmacist Scorecard of Spirodex by Gaspari Nutrition

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

Low disclosure
Ingredient Transparency · database check
Low

Most active ingredients don't disclose an individual amount — you can't tell how much of each you're getting.

Why this rating?
  • The label discloses an exact amount for 1 of its 6 active ingredients.
  • “Spiroblend (Combination)” is a proprietary blend — the label gives one combined amount (250 mg) without saying how much of each component you get.

Spirodex contains 6 active ingredients. The primary ones are three caffeine sources: caffeine itself, black tea (Camellia sinensis), and guarana (Paullinia cupana extract), which together make this a potent stimulant product.

The other actives are hordenine (a stimulant-like compound), Oxytrolis falcata extract, and Geranium maculatum extract. The product also contains several inactive ingredients—fillers and binders like dicalcium phosphate, magnesium stearate, and silicon dioxide, plus a capsule coating.

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: mood enhancing stimulant compound.
  • We looked for evidence on: Mental alertness, Athletic performance, Attention deficit-hyperactivity disorder (ADHD), Cognitive function, Depression, Stress — and 3 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: Black Tea is rated "Likely Effective" for Mental alertness.

Caffeine in this product is effective for neonatal apnea and postoperative headache, and likely effective for mental alertness and athletic performance. Black tea is likely effective for mental alertness and possibly effective for several conditions including heart health and bone strength.

Guarana's effectiveness for its listed uses—cancer-related appetite loss, anxiety, athletic performance, and cancer fatigue—has insufficient reliable evidence to rate. No effectiveness data is on file for hordenine, Oxytrolis falcata, or Geranium maculatum.

The evidence, ingredient by ingredient Caffeine Hordenine Black Tea Guarana

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 4 of the 4 matched ingredients.
  • Pregnancy & breastfeeding safety ratings cover 3 of 4.
  • General safety write-ups exist for 4 of 4.
  • Remember: this measures how much safety information exists. Thin data is not the same as being safe.

Caffeine in moderate doses is generally well tolerated in healthy adults, though high doses can cause serious side effects. Common side effects include anxiety, insomnia, jitteriness, tremors, nausea, diarrhea, and headache.

Rarely, stroke has been reported. Black tea's safety profile is similar, with most adverse effects tied to its caffeine content—insomnia, nervousness, restlessness, tachycardia, and nausea are most common.

Hordenine has very limited human safety data; it acts as a stimulant and theoretically may cause tachycardia and high blood pressure, but this hasn't been confirmed in humans. Regarding pregnancy, high caffeine intake may be harmful—keep intake moderate and speak with your doctor about safe limits.

For breastfeeding, caffeine passes into breast milk; moderate intake is usually considered acceptable, but it can affect the baby, so keep consumption limited.

Side effects, ingredient by ingredient Caffeine Hordenine Black Tea Guarana

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?
  • 4 of the 4 matched ingredients can interact with medications — Guarana, Caffeine, Black Tea, Hordenine.
  • The most serious interaction on file is rated Major.
  • Some involve high-stakes drug classes: anticoagulant / antiplatelet drugs; diabetes medications; lithium.
  • For scale: 807 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 Spirodex, double-check with your pharmacist if you take ephedrine or any stimulant drugs (Major severity risk). Then review whether you use seizure-preventing medications like phenobarbital, carbamazepine, valproate, or felbamate; antipsychotics like clozapine; blood thinners like warfarin; antidepressants like fluvoxamine; monoamine oxidase inhibitors (MAOIs); or medications affected by liver enzyme CYP2D6, as these have documented Moderate or Minor interactions.

Check your own medication Run your meds through the checker above

The bottom line

Scorecard at a glanceFormula with limited ingredient disclosure with clinical evidence supporting its stated purpose. Major medication interactions have been identified, and safety information is well characterized.

Spirodex is a caffeine-heavy stimulant supplement best suited for people seeking a boost to alertness or athletic performance who don't take ephedrine, seizure medications, clozapine, certain antidepressants, or MAOIs. Anyone on prescription medications should check them with the tool on this page before starting.

Pregnant or breastfeeding individuals should talk with their doctor or pharmacist about whether this product is right for them given its high caffeine load.

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

Assessment coverage: 4 of 6 active ingredients matched to our full ingredient reviews (monographs). Based on the product label dated Nov 25, 2011.

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 Spirodex, straight from the product label.

Brand Gaspari Nutrition
Barcode (UPC) 646511007024
Net contents 75 Spirotab(s)
Market status On market
Date entered into DSLD Nov 25, 2011
DSLD ID 2064
Product type Other Combinations
Supplement form Tablet Or Pill
Dietary claims / uses All Other, Structure/Function
Intended target group(s) Adult (18 - 50 Years)
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 Spirodex by Gaspari Nutrition, 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:
1 Tablet(s)
Maximum serving Sizes:
2 Tablet(s)
Servings per container
75
UPC/BARCODE
646511007024
IngredientAmount% DV
Caffeine175 mg--
Hordenine0 NP--
Camellia sinensis0 NP--
Spiroblend (Combination)250 mg--
Oxytropis falcate extract0 NP--
Geranium maculatum extract0 NP--
Paullinia cupana [whole plant] extract0 NP--

Other ingredients: Dicalcium Phosphate, Stearic Acid, Magnesium Stearate, Croscarmellose Sodium, Silicon Dioxide, Hydroxypropyl Methylcellulose, Polyethylene Glycol, Water, Titanium Dioxide, FD&C Yellow No. 5

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

DIRECTIONS FOR USE: As a dietary supplement, orally ingest 1-2 Spirotabs once per day with 16-20 ounces of water after breakfast/ before noon.

Due to the exceptional potency of this product, begin by taking 1 Spirotab once per day for at least 4 days to assess tolerance to this product before increasing dosage to 2 Spirotabs once per day.

Precautions

KEEP OUT OF REACH OF CHILDREN.

Do not use product if you are nursing, pregnant, or are attempting to become pregnant.

BEFORE USING THIS PRODUCT SEEK ADVICE OF A PHYSICIAN.

Do not exceed this dosage under any circumstances.

DO NOT PURCHASE OR USE THIS PRODUCT IF TAMPER PROOF SAFETY SEAL IS NOT INTACT.

Do not take this product if you have or are at risk for high or low blood pressure, cardiac disease, stroke, seizure disorders, diabetes, kidney/liver disease, asthma, migraine headaches, psychiatric disease, HIV or AIDS, have difficulty urinating or if you are taking a MAO inhibitor.

Do not take this product with any prescription drugs, over-the-counter products, other dietary supplements or if you have any pre-existing medical conditions.

Do not take this product with other stimulants or if you are prone to dehydration or are exposed to excessive heat.

Do not use this product for more than 6 weeks continuously without a 4 week break.

Immediately discontinue use and call your physician if you experience any adverse reactions, including, but not limited to, rapid heart beat, dizziness, severe headache, shortness of breath or chest pains.

Individual responses to dietary supplements may vary, for this reason some consumers of this product may need to consume only one (1) Spirotab per day while others may need to consume two (2) Spirotabs per day. Do not exceed the suggested amount (two Spirotabs) under any circumstances as this will not increase benefits. This product should be used in conjunction with a proper diet and exercise program. Before starting any weight loss program, consult with your physician.

PROFESSIONAL USE ONLY

This product may contain ingredients banned by certain sports or professional organizations. If you are subject to testing for performance enhancing compounds or any type of drug testing do not use this product under any circumstances. User assumes all risks, liabilities, and consequences related to performance enhancing testing and use of this product.

WARNING: This dietary supplement is intended to be used by healthy adults 18+ years of age.

WARNING: THIS IS A HIGHLY POTENT PRODUCT. READ ENTIRE LABEL BEFORE USE.

FDA Disclaimer Statement

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

Storage

Store at a controlled room temperature of 59 to 86F (15 to 30 C). Protect from moisture, humidity, and sunlight.

Formula

425mg Once Per Day Dose

General Statements

ADDED VALUE 25% MORE FREE

MOOD ENHANCING STIMULANT COMPOUND†

Brand IP Statement(s)

© 2010 Gaspari Nutrition, Inc. Gaspari Nutrition and Spirodex are registered trademarks of Gaspari Nutrition – All Rights Reserved.

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

Spirodex by Gaspari Nutrition label

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

Spirodex 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 Spirodex by Gaspari Nutrition

These are the 6 active ingredients this product is made of. Select any to open its full monograph.

Serving size1 Tablet(s) Dosage formTablet Or Pill Servings per container75 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.

Caffeine

Interacts with
655 drugs
175 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

Spiroblend (Combination)

250 mg per serving

Other (inactive) ingredients: Dicalcium Phosphate, Stearic Acid, Magnesium Stearate, Croscarmellose Sodium, Silicon Dioxide, Hydroxypropyl Methylcellulose, Polyethylene Glycol, Water, Titanium Dioxide, FD&C Yellow No. 5. These complete the product’s ingredient list but are not active constituents.

Interaction report

Spirodex by Gaspari Nutrition Drug Interactions

Want to check YOUR meds against Spirodex?

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
807Drugs
8 Major 572 Moderate 227 Minor

Ingredients driving the most interactions

Camellia sinensis 694
Caffeine 655
Paullinia cupana [whole plant] extract 655
Hordenine 329

Individual Drug Interactions

The ingredients in Spirodex interact with 807 drugs. Click any drug to see the details.

4 of the 6 ingredients in Spirodex interact with drugs. Each result below shows which ingredient is responsible. Camellia sinensis Caffeine Paullinia cupana [whole plant] extract Hordenine

Each ingredient & the kinds of drugs it affects

For each ingredient in Spirodex 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.

Camellia sinensis46 drug types · 694 drugs

Ephedrine

Theoretically, concomitant use might increase the risk for simulant adverse effects.
Black tea contains caffeine. 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. Tell patients to avoid taking caffeine with ephedrine and other stimulants.

Likelihood Probable Evidence D
Adenosine (Adenocard)

Theoretically, black tea might decrease the vasodilatory effects of adenosine and interfere with its use prior to stress testing.
Black tea contains caffeine. Caffeine is a competitive inhibitor of adenosine at the cellular level. However, 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 such as caffeine, as well as 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, black tea may increase the risk of bleeding if used with anticoagulant or antiplatelet drugs.
Black tea contains caffeine. Caffeine is reported to have antiplatelet activity. Theoretically, the caffeine in black tea might increase the risk of bleeding when used concomitantly with antiplatelet drugs. However, this interaction has not been reported in humans.

Likelihood Possible Evidence D
Beta-Adrenergic Agonists

Theoretically, concomitant use of large amounts of black tea might increase cardiac inotropic effects of beta-agonists.
Black tea contains caffeine. Caffeine can increase cardiac inotropic effects of beta-agonists.

Likelihood Probable Evidence D
Carbamazepine (Tegretol)

Theoretically, black tea might reduce the effects of carbamazepine and increase the risk for convulsion.
Black tea contains caffeine. Animal research suggests that 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 B
Cimetidine (Tagamet)

Theoretically, concomitant use might increase the effects and adverse effects of caffeine in black tea.
Black tea contains caffeine. Cimetidine can reduces caffeine clearance by 31% to 42%.

Likelihood Likely Evidence B
Clozapine (Clozaril)

Theoretically, black tea might increase the levels and adverse effects of clozapine and acutely exacerbate psychotic symptoms.
Concomitant administration of black tea and clozapine might theoretically cause acute exacerbation of psychotic symptoms due to the caffeine in black tea. Caffeine can increase the effects and toxicity of clozapine. Caffeine doses of 400-1000 mg daily inhibit clozapine metabolism. Clozapine is metabolized by cytochrome P450 1A2 (CYP1A2). Researchers speculate that caffeine might inhibit CYP1A2. However, there is no reliable evidence that caffeine affects CYP1A2. There is also speculation that genetic factors might make some patients be more sensitive to the interaction between clozapine and caffeine.

Likelihood Possible Evidence B
Contraceptive Drugs

Theoretically, concomitant use might increase the effects and adverse effects of caffeine found in black tea.
Black tea contains caffeine. Oral contraceptive drugs can decrease caffeine clearance by 40% to 65%.

Likelihood Probable Evidence B
Cytochrome P450 1A2 (Cyp1A2) Inhibitors

Theoretically, concomitant use might increase the levels and adverse effects of caffeine.
Black tea contains caffeine. Caffeine is metabolized by CYP1A2,. Theoretically, drugs that inhibit CYP1A2 may decrease the clearance rate of caffeine from black tea and increase caffeine levels.

Likelihood Possible Evidence D
Dipyridamole (Persantine)

Theoretically, black tea might decrease the vasodilatory effects of dipyridamole and interfere with its use prior to stress testing.
Black tea contains caffeine. Caffeine is a methylxanthine that may inhibit dipyridamole-induced vasodilation. It is recommended that methylxanthines such as caffeine, as well as methylxanthine-containing products such as black tea, 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 might increase the risk of adverse effects from caffeine.
Black tea contains caffeine. In human research, disulfiram decreases the clearance and increases the half-life of caffeine.

Likelihood Probable Evidence B
Diuretic Drugs

Theoretically, using black tea with diuretic drugs might increase the risk of hypokalemia.
Black tea contains caffeine. 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.
Black tea contains caffeine. Estrogen inhibits caffeine metabolism.

Likelihood Probable Evidence B
Ethosuximide (Zarontin)

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

Likelihood Possible Evidence D
Felbamate (Felbatol)

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

Likelihood Possible Evidence D
Flutamide (Eulexin)

Theoretically, black tea might increase the levels and adverse effects of flutamide.
Black tea contains caffeine. In vitro evidence suggests that caffeine can inhibit the metabolism of flutamide. Theoretically, concomitant use of caffeine and flutamide might increase serum concentrations of flutamide and increase the risk of adverse effects.

Likelihood Possible Evidence D
Fluvoxamine (Luvox)

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

Likelihood Probable Evidence B
Lithium

Theoretically, abrupt black tea withdrawal might increase the levels and adverse effects of lithium.
Black tea contains caffeine. Abrupt caffeine withdrawal can increase serum lithium levels. Two cases of lithium tremor that worsened with abrupt coffee withdrawal have been reported.

Likelihood Probable Evidence D
Monoamine Oxidase Inhibitors (Maois)

Theoretically, concomitant use might increase the risk of a hypertensive crisis.
Black tea contains caffeine. 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 caffeinate coffee and took the MAOI tranylcypromine presented with severe hypertension. Hypertension was resolved after the patients switched to drinking decaffeinated coffee.

Likelihood Possible Evidence D
Nicotine

Theoretically, concomitant use might increase the risk of hypertension.
Black tea contains caffeine. 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
Organic Anion-Transporting Polypeptide Substrates (Oatp)

Theoretically, black tea might reduce the absorption of organic anion-transporting polypeptide (OATP) substrates.
In vitro, black tea extract inhibits organic anion-transporting polypeptide (OATP)2B1. OATP2B1 is expressed in the small intestine and liver and is responsible for the uptake of drugs and other compounds. In an animal model, black tea extract was found to inhibit the absorption of rosuvastatin, a substrate of OATP2B1. However, this effect has not been reported in humans.

Likelihood Possible Evidence D
Pentobarbital (Nembutal)

Theoretically, black tea might decrease the effects of pentobarbital.
Black tea contains caffeine. Theoretically, caffeine might negate the hypnotic effects of pentobarbital.

Likelihood Possible Evidence B
Phenobarbital (Luminal)

Theoretically, black tea might reduce the effects of phenobarbital and increase the risk for convulsions.
Black tea contains caffeine. Animal research suggests that caffeine can decrease the anticonvulsant activity of phenobarbital. 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.
Black tea contains 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, black tea might reduce the effects of phenytoin and increase the risk for convulsions.
Black tea contains caffeine. 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
Camellia sinensis full monograph & all 46 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

Paullinia cupana [whole plant] extract41 drug types · 655 drugs

Ephedrine

Theoretically, concomitant use might increase the risk for stimulant adverse effects.
Guarana contains caffeine. 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, guarana might decrease the vasodilatory effects of adenosine and interfere with its use prior to stress testing.
Guarana contains caffeine. Caffeine is a competitive inhibitor of adenosine at the cellular level. However, 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, guarana may increase the risk of bleeding if used with anticoagulant or antiplatelet drugs.
In vitro and animal research suggests that guarana extract can inhibit platelet aggregation. This effect may be due to the caffeine in guarana, which is also reported to have antiplatelet activity. This interaction has not been reported in humans.

Likelihood Possible Evidence D
Beta-Adrenergic Agonists

Theoretically, concomitant use might increase the clinical effects of beta-adrenergic agonists.
Guarana contains caffeine. Theoretically, concomitant use of large amounts of caffeine might increase cardiac inotropic effects of beta-agonists.

Likelihood Probable Evidence D
Carbamazepine (Tegretol)

Theoretically, guarana 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 given to animals 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 two-fold in healthy individuals.

Likelihood Possible Evidence D
Cimetidine (Tagamet)

Theoretically, concomitant use might increase the effects and adverse effects of caffeine in guarana.
Guarana contains caffeine. Cimetidine decreases the rate of caffeine clearance by 31% to 42%.

Likelihood Likely Evidence B
Clozapine (Clozaril)

Theoretically, guarana might increase the levels and adverse effects of clozapine and acutely exacerbate psychotic symptoms.
Guarana contains caffeine. Caffeine can 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). Researchers speculate that caffeine might inhibit CYP1A2. However, there is no reliable evidence that caffeine affects CYP1A2. There is also speculation that genetic factors might make some patients more sensitive to the interaction between clozapine and caffeine.

Likelihood Possible Evidence B
Dipyridamole (Persantine)

Theoretically, guarana might decrease the vasodilatory effects of dipyridamole and interfere with its use prior to stress testing.
Guarana contains caffeine. Caffeine might inhibit 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 than adenosine-induced stress testing.

Likelihood Probable Evidence B
Disulfiram (Antabuse)

Theoretically, disulfiram might increase the risk of adverse effects from caffeine.
In human research, disulfiram decreases the clearance and increases the half-life of caffeine.

Likelihood Probable Evidence D
Diuretic Drugs

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

Likelihood Possible Evidence D
Estrogens

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

Likelihood Probable Evidence B
Ethosuximide (Zarontin)

Theoretically, guarana might reduce the effects of ethosuximide and increase the risk for convulsions.
Guarana contains caffeine. Animal research shows that caffeine 92.4 mg/kg can decrease the anticonvulsant activity of ethosuximide. This effect has not been observed in humans.

Likelihood Possible Evidence D
Felbamate (Felbatol)

Theoretically, guarana might reduce the effects of felbamate and increase the risk for convulsions.
Guarana contains caffeine. Animal research shows that a high dose of caffeine 161.7 mg/kg can decreases the anticonvulsant activity of felbamate. This effect has not been observed in humans.

Likelihood Possible Evidence D
Flutamide (Eulexin)

Theoretically, guarana might increase the levels and adverse effects of flutamide.
Guarana contains caffeine. In vitro evidence shows 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.
Guarana contains caffeine. Fluvoxamine reduces caffeine metabolism.

Likelihood Probable Evidence D
Lithium

Theoretically, abrupt guarana withdrawal might increase the levels and adverse effects of lithium.
Guarana contains caffeine. Theoretically, abrupt caffeine withdrawal might increase serum lithium levels. There are two case reports of lithium tremor that worsened upon abrupt coffee withdrawal.

Likelihood Probable Evidence D
Monoamine Oxidase Inhibitors (Maois)

Theoretically, concomitant use might increase the risk of a hypertensive crisis.
Guarana contains caffeine. Caffeine has been shown to inhibit 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.
Guarana contains caffeine. 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 D
Pentobarbital (Nembutal)

Theoretically, guarana might decrease the effects of pentobarbital.
Guarana contains caffeine. In vivo evidence suggests that caffeine can negate the hypnotic effects of pentobarbital in humans. However, animal research suggests that guarana does not alter the hypnotic effect of pentobarbital.

Likelihood Possible Evidence B
Phenobarbital (Luminal)

Theoretically, guarana might reduce the effects of phenobarbital and increase the risk for convulsions.
Guarana contains caffeine. Animal research shows that caffeine can decrease the anticonvulsant activity of phenobarbital. 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.
Guarana contains 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, guarana might reduce the effects of phenytoin and increase the risk for convulsions.
Guarana contains caffeine. Animal research shows 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, guarana might increase the levels and clinical effects of pioglitazone.
Guarana contains caffeine. 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
Riluzole (Rilutek)

Theoretically, concomitant use might increase the levels and adverse effects of both caffeine and riluzole.
Guarana contains caffeine. 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
Stimulant Drugs

Theoretically, concomitant use might increase stimulant adverse effects.
Guarana contains caffeine. Due to the central nervous system (CNS) stimulant effects of caffeine, concomitant use with stimulant drugs can increase the risk of adverse effects.

Likelihood Possible Evidence D
Paullinia cupana [whole plant] extract full monograph & all 41 interactions

Hordenine3 drug types · 329 drugs

Monoamine Oxidase Inhibitors (Maois)

Hordenine is structurally similar to tyramine In vitro research shows that hordenine is a selective substrate for monoamine oxidase-B in the liver. Theoretically, concomitant use of hordenine with MAOIs might increase blood pressure, potentially leading to a hypertensive crisis.
Some MAOIs include isocarboxazid (Marplan), phenelzine (Nardil), selegiline (Eldepryl, Emsam, Zelapar), and tranylcypromine (Parnate).

Likelihood Possible Evidence D
Stimulant Drugs

Hordenine is structurally similar to N-methyltyramine and synephrine, constituents in bitter orange known to have stimulant properties. Theoretically, taking hordenine with drugs with stimulant properties might increase the risk of hypertension and other adverse cardiovascular effects.
Some of these drugs include amphetamine, caffeine, methylphenidate, pseudoephedrine, and many others.

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

Hordenine weakly inhibits cytochrome P450 2D6 (CYP2D6) enzymes in vitro. Theoretically, hordenine might increase the levels of CYP2D6 substrates.
Some of drugs that are CYP2D6 substrates include amitriptyline (Elavil), clozapine (Clozaril), codeine, desipramine (Norpramin), donepezil (Aricept), fentanyl (Duragesic), flecainide (Tambocor), fluoxetine (Prozac), meperidine (Demerol), methadone (Dolophine), metoprolol (Lopressor, Toprol XL), olanzapine (Zyprexa), ondansetron (Zofran), tramadol (Ultram), trazodone (Desyrel), and others.

Likelihood Possible Evidence D
Hordenine full monograph & interactions
The maker

Brand information

Manufacturer and brand details for Spirodex, from the product label.

Gaspari Nutrition

See all Gaspari Nutrition products
Web Address
www.gasparinutrition.com
Pharmacist Counseling Corner

Spirodex by Gaspari Nutrition: Common Questions

Does Spirodex by Gaspari Nutrition interact with any medications?
Yes. Based on its ingredients, Spirodex has a known interaction with 807 medications, including 8 rated major. Use the checker to see how it interacts with a specific drug.
How can one product interact with so many drugs?
Spirodex contains 6 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.
Is Spirodex safe to take if I'm pregnant or breastfeeding?
The product's high caffeine content carries caution in pregnancy—high intake may be harmful, so you'll want to discuss safe limits with your doctor. During breastfeeding, caffeine passes into breast milk and can affect the baby, so keeping intake moderate and talking with your pharmacist is important. Hordenine has no safety data in pregnancy or breastfeeding, so that's another reason to check with your provider first.
What are the most common side effects of caffeine in this product?
Anxiety, insomnia, jitteriness, tremors, nausea, diarrhea, and headache are the most frequent side effects in moderate use. High doses increase the risk of more serious effects. Guarana specifically may cause stomach burning and dizziness as well.
Will Spirodex help me with athletic performance?
Caffeine is likely effective for athletic performance, which is one of Spirodex's ingredients. However, guarana and the other actives don't have enough evidence to rate their effectiveness for this purpose.
What is hordenine, and is it safe?
Hordenine is a stimulant-like compound structurally similar to compounds in bitter orange. Human safety data is very limited. It theoretically may cause stimulant side effects like elevated heart rate and high blood pressure, but this hasn't been studied or reported in people, so there's real uncertainty about its safety profile.
Can I use Spirodex with my blood thinner (warfarin)?
Black tea's high caffeine content may reduce warfarin's blood-thinning effect, especially if you consume large amounts of tea regularly. This is a Moderate severity interaction, so you absolutely need to check with your pharmacist or doctor before starting this product.
What is Spiroblend, and does it interact with medications?
Spiroblend is listed as a combination ingredient; its individual components are already checked as separate actives in this product, so its interactions are covered by those analyses.

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

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Label information is sourced from the NIH Dietary Supplement Label Database and reflects the product version on file; always read your actual product label. This page is for education only and is not a substitute for professional medical advice. Confirm with your pharmacist or doctor before combining supplements and medications.

Spirodex label
Go deeper

The Full Monographs Behind Spirodex’s Ingredients

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

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

Hordenine

Interacts with 329 drugs

Hordenine is a natural alkaloid found in barley and some cacti that is marketed as a stimulant for energy, focus, and fat loss, but solid human evidence for these benefits is lacking. Its sa...

Read the full Hordenine monograph → Herb & supplement monograph

Black Tea

Interacts with 694 drugs

Black tea is a popular caffeinated drink made from the fully oxidized leaves of the Camellia sinensis plant, and it contains caffeine and antioxidant plant compounds. Moderate tea drinking i...

Read the full Black Tea monograph → Herb & supplement monograph

Guarana

Interacts with 655 drugs

Guarana is an Amazonian seed that is naturally high in caffeine, which explains most of its stimulant and energy effects. While it may give a short-term boost in alertness and reduce fatigue...

Read the full Guarana monograph →
Sources

Sources & How We Checked

Spirodex'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 503 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.

Caffeine 236 references
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See these in context on the Black Tea monograph →

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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.

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