Major interaction on record — check this product against your medications before combining. Based on 10 of 12 ingredients. Check your meds →
Dietary supplement

BZRK Crystal Blue Ingredients & Drug Interactions

by Black Magic

BZRK Crystal Blue label
See full label image
Powder 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 BZRK Crystal Blue 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

BZRK Crystal Blue is a dietary supplement by Black Magic with 12 active ingredients. Its ingredients are commonly taken for exercise performance, muscle soreness and fatigue, blood flow and circulation.Based on those ingredients, 911 medications have a known interaction with it, the most serious rated major. The ingredients most likely to interact are Caffeine Anhydrous, Kola Nut Leaf Extract, CognatiQ. Use the checker below to test your specific medication, or read the full HelloPharmacist Interaction Report.

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Check Your Meds Against BZRK Crystal Blue by Black Magic

Ask about any prescription or over-the-counter medication and we check it for interactions with BZRK Crystal Blue by Black Magic — and tell you which ingredient is responsible.

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HelloPharmacist Scorecard of BZRK Crystal Blue by Black Magic

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

Partial disclosure
Ingredient Transparency · database check
Partial

Most active ingredients list an amount, but at least one is hidden in a blend or missing.

Why this rating?
  • The label discloses an exact amount for 6 of its 12 active ingredients.
  • “Possessed Matrix” is a proprietary blend — the label gives one combined amount (1,620 mg) without saying how much of each component you get.

BZRK Crystal Blue contains 12 ingredients total. The active ones are L-Tyrosine (an amino acid), Caffeine Anhydrous (the stimulant from caffeine), Caffeine (stimulant), L-Citrulline DL-Malate (an amino acid blend), glycerol (GlycerPump), betaine anhydrous (a methyl donor), beta-alanine (Beta-O), Adhatoda vasaka extract (Malabar nut), and proprietary blends or extracts including Huperzia serrata leaf extract, CognatiQ (coffee extract), AstraGin, and Kola Nut Leaf Extract.

The remaining ingredients—silica, natural and artificial flavors, malic acid, citric acid, sucralose, and acesulfame potassium—are inactive fillers and flavor agents.

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: Pre-workout supplement for athletic performance.
  • We looked for evidence on: Athletic performance, Exercise-induced muscle soreness, Exercise-induced muscle breakdown, Mental alertness, Fatigue, Cognitive function — and 4 related terms.
  • The strongest evidence on file: Caffeine is rated "Effective" for Postoperative headache (Natural Medicines).
  • Also on file: Caffeine is rated "Likely Effective" for Athletic performance, Mental alertness.
  • Also on file: Coffee is rated "Likely Effective" for Mental alertness.

L-Tyrosine is effective for phenylketonuria (PKU), a genetic disorder, and possibly effective for cognitive function and memory, though evidence for athletic performance is limited. Caffeine is effective for neonatal apnea and postoperative headache, and likely effective for mental alertness and athletic performance.

L-Citrulline is possibly effective for athletic performance. Glycerol is likely effective for constipation and possibly effective for athletic performance.

Betaine is effective for homocystinuria and possibly effective for high homocysteine levels. Beta-alanine is possibly effective for athletic and physical performance.

CognatiQ coffee extract is likely effective for mental alertness and possibly effective for Parkinson's disease, heart failure, diabetes, and overall mortality. We don't have effectiveness data on file for AstraGin, Huperzia serrata, Adhatoda vasaka, or Kola Nut Leaf Extract.

The evidence, ingredient by ingredient L-citrulline Tyrosine Caffeine Toothed Clubmoss Malabar Nut Cola Nut Glycerol Betaine Anhydrous

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 9 of the 10 matched ingredients.
  • Pregnancy & breastfeeding safety ratings cover 10 of 10.
  • General safety write-ups exist for 10 of 10.
  • Remember: this measures how much safety information exists. Thin data is not the same as being safe.

L-Tyrosine is generally well tolerated in healthy adults but not well studied for long-term use; common side effects are fatigue, headache, heartburn, and nausea. Caffeine is generally safe in moderate amounts but can cause anxiety, insomnia, tremor, nausea, and rarely stroke; high doses carry serious risks.

L-Citrulline is generally well tolerated with gastrointestinal discomfort and heartburn as the main complaints. Glycerol is well tolerated orally in normal amounts but can cause bloating, diarrhea, nausea, vomiting, dizziness, and headache.

Betaine is generally well tolerated; reported side effects include body odor, diarrhea, nausea, vomiting, and GI distress. Beta-alanine commonly causes harmless pins-and-needles sensations (paresthesia) and flushing, usually starting on the scalp and lasting about an hour.

Adhatoda vasaka has limited human safety data. Regarding pregnancy and breastfeeding: L-Tyrosine and L-Citrulline have insufficient data — talk to your doctor or pharmacist for personalized advice.

Caffeine should be limited in pregnancy and moderated while breastfeeding, as amounts pass into breast milk. Beta-alanine and Adhatoda vasaka are best avoided during pregnancy and breastfeeding due to insufficient safety data.

Side effects, ingredient by ingredient L-citrulline Tyrosine Caffeine Toothed Clubmoss Malabar Nut Cola Nut Glycerol Betaine Anhydrous

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?
  • 6 of the 10 matched ingredients can interact with medications — Toothed Clubmoss, Cola Nut, Caffeine, Coffee, Tyrosine, among others.
  • The most serious interaction on file is rated Major.
  • Some involve high-stakes drug classes: anticoagulant / antiplatelet drugs; diabetes medications; lithium; Parkinson's medications.
  • For scale: 911 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.

Check with your pharmacist before taking this product if you use ephedrine (Major risk), sedating barbiturates (pentobarbital), blood-thinning or vasodilating agents (dipyridamole), antipsychotics (clozapine), acid reflux medications (cimetidine), quinolone antibiotics, anticonvulsants (phenobarbital, carbamazepine, lamotrigine), blood pressure medications, phosphodiesterase-5 inhibitors (like sildenafil), levodopa for Parkinson's disease, thyroid hormones, alcohol-deterrent drugs (disulfiram), or antidepressants (fluvoxamine). No interactions are documented for the ingredients we could check: glycerol, betaine, and beta-alanine.

Check your own medication Run your meds through the checker above

The bottom line

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

This product is targeted at people seeking mental alertness and athletic performance support, with a substantial caffeine content from multiple sources. If you take ephedrine, any blood pressure medication, any anticonvulsant, any antipsychotic, or levodopa, talk to your pharmacist before using it.

Anyone sensitive to stimulants, pregnant, breastfeeding, or on multiple medications should check with their doctor or pharmacist first.

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 May 21, 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 BZRK Crystal Blue, straight from the product label.

Brand Black Magic
Net contents 16.23 Ounce(s); 460 Gram(s)
Market status On market
Date entered into DSLD May 21, 2025
DSLD ID 327394
Product type Other Combinations
Supplement form Powder
Dietary claims / uses All Other
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 BZRK Crystal Blue by Black Magic, 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:
20.17 Gram(s)
Maximum serving Sizes:
20.17 Gram(s)
Servings per container
25
IngredientAmount% DV
L-Tyrosine0 NP--
Caffeine Anhydrous0 NP--
Caffeine0 NP--
L-Citrulline DL-Malate7000 mg--
Possessed Matrix1620 mg--
AstraGin50 mg--
GlycerPump2500 mg--
Huperzia serrata Leaf Extract0 NP--
Betaine Anhydrous1000 mg--
CognatiQ75 mg--
Beta-O3200 mg--
Adhatoda vasaka Extract0 NP--
Kola Nut Leaf Extract0 NP--

Other ingredients: Silica, Natural & Artificial Flavors, Malic Acid, Citric Acid, Sucralose, 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.
General Statements

From the other side Less Luck More Skill

Formulation

Psychoactive waves Supernatural Pre-workout

FDA Statement of Identity

Dietary Supplement

Formula

Crystal Blue Naturally & Artificially flavored

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

See for yourself

BZRK Crystal Blue by Black Magic label

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

BZRK Crystal Blue 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 BZRK Crystal Blue by Black Magic

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

Serving size20.17 Gram(s) Dosage formPowder Servings per container25 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.

L-Citrulline DL-Malate

Interacts with
178 drugs
7000 mg per serving

L-citrulline is an amino acid that the body turns into L-arginine to help make nitric oxide, which relaxes blood vessels and may improve blood flow. I...

L-Citrulline DL-Malate monograph & interactions

AstraGin

50 mg per serving Form: Astragalus extract, Panax notoginseng extract

GlycerPump

No known
interactions
2500 mg per serving Form: Glycerol, Powder

Glycerol (glycerin) is a sweet, syrupy compound made naturally in the body and widely used in foods, skin products, and medicines. It is well establis...

GlycerPump monograph & interactions

Betaine Anhydrous

No known
interactions
1000 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

CognatiQ

Interacts with
591 drugs
75 mg per serving Form: Coffee Whole Fruit Extract

Coffee is a widely consumed beverage made from roasted coffee beans, valued mainly for its caffeine, which boosts alertness and energy. For most healt...

CognatiQ monograph & interactions

Beta-O

No known
interactions
3200 mg per serving Form: Beta-Alanine, Orotic Acid

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-O monograph & interactions

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

Interaction report

BZRK Crystal Blue by Black Magic Drug Interactions

Want to check YOUR meds against BZRK Crystal Blue?

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
911Drugs
8 Major 811 Moderate 92 Minor

Ingredients driving the most interactions

Caffeine Anhydrous 655
Kola Nut Leaf Extract 655
CognatiQ 591
Huperzia serrata Leaf Extract 219
L-Citrulline DL-Malate 178

Individual Drug Interactions

The ingredients in BZRK Crystal Blue interact with 911 drugs. Click any drug to see the details.

6 of the 12 ingredients in BZRK Crystal Blue interact with drugs. Each result below shows which ingredient is responsible. Caffeine Anhydrous Kola Nut Leaf Extract CognatiQ Huperzia serrata Leaf Extract L-Citrulline DL-Malate L-Tyrosine

Each ingredient & the kinds of drugs it affects

For each ingredient in BZRK Crystal Blue 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.

Caffeine Anhydrous41 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 Anhydrous full monograph & all 41 interactions

Kola Nut Leaf Extract41 drug types · 655 drugs

Adenosine (Adenocard)

Theoretically, cola nut might decrease the vasodilatory effects of adenosine and interfere with its use prior to stress testing.
Cola nut 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 (including cola nut) 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
Alcohol (Ethanol)

Theoretically, alcohol might increase the levels and adverse effects of the caffeine in cola nut.
Cola nut contains caffeine. Concomitant use of alcohol and caffeine can increase caffeine serum concentrations and the risk of caffeine adverse effects. Alcohol reduces caffeine metabolism.

Likelihood Probable Evidence D
Anticoagulant/Antiplatelet Drugs

Theoretically, cola nut may increase the risk of bleeding if used with anticoagulant or antiplatelet drugs.
Cola nut contains caffeine. Caffeine is reported to have antiplatelet activity. This interaction has not been reported in humans.

Likelihood Unlikely Evidence D
Beta-Adrenergic Agonists

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

Likelihood Probable Evidence D
Carbamazepine (Tegretol)

Theoretically, cola nut might reduce the effects of carbamazepine and increase the risk for convulsions.
Cola nut contains caffeine. 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
Clozapine (Clozaril)

Theoretically, cola nut might increase the levels and adverse effects of clozapine and acutely exacerbate psychotic symptoms.
Cola nut contains caffeine. 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 more sensitive to the interaction between clozapine and caffeine.

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

Theoretically, CYP1A2 inhibitors might increase the levels and adverse effects of the caffeine in cola nut.
Cola nut contains caffeine. Caffeine is metabolized by CYP1A2,.

Likelihood Possible Evidence D
Dipyridamole (Persantine)

Theoretically, cola nut might decrease the vasodilatory effects of dipyridamole and interfere with its use prior to stress testing.
Cola nut contains caffeine. Caffeine may inhibit dipyridamole-induced vasodilation. It is recommended that methylxanthines and methylxanthine-containing products, such as cola nut, be stopped 24 hours prior to pharmacological stress tests. Methylxanthines appear more likely to interfere with dipyridamole than with adenosine-induced stress testing.

Likelihood Probable Evidence B
Disulfiram (Antabuse)

Theoretically, disulfiram might increase the levels and adverse effects of the caffeine in cola nut.
Cola nut contains caffeine. In human research, disulfiram decreases the rate of caffeine clearance.

Likelihood Probable Evidence D
Diuretic Drugs

Theoretically, using cola nut with diuretic drugs might increase the risk of hypokalemia.
Cola nut contains caffeine. In excessive amounts, caffeine can reduce potassium levels due to stimulation of the sodium-potassium pump. Certain diuretics can also lower potassium levels.

Likelihood Possible Evidence D
Ephedrine

Theoretically, concomitant use might increase the risk for stimulant adverse effects.
Cola nut 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.

Likelihood Possible Evidence D
Estrogens

Theoretically, estrogens might increase the levels and adverse effects of the caffeine in cola nut.
Cola nut contains caffeine. Estrogen inhibits caffeine metabolism.

Likelihood Probable Evidence B
Ethosuximide (Zarontin)

Theoretically, cola nut might reduce the effects of ethosuximide and increase the risk for convulsions.
Cola nut contains caffeine. 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, cola nut might reduce the effects of felbamate and increase the risk for convulsions.
Cola nut contains caffeine. 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, cola nut might increase the levels and adverse effects of flutamide.
Cola nut contains caffeine. In vitro evidence suggests that caffeine can inhibit the metabolism of flutamide. This effect has not been reported in humans.

Likelihood Possible Evidence D
Fluvoxamine (Luvox)

Theoretically, fluvoxamine might increase the levels and adverse effects of the caffeine in cola nut.
Cola nut contains caffeine. Fluvoxamine reduces caffeine metabolism.

Likelihood Probable Evidence D
Lithium

Theoretically, abrupt cola nut withdrawal might increase the levels and adverse effects of lithium.
Cola nut contains caffeine. Abrupt caffeine withdrawal can 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.
Cola nut 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 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.
Cola nut 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, cola nut might decrease the effects of pentobarbital.
Cola nut contains caffeine. Theoretically, caffeine might negate the hypnotic effects of pentobarbital.

Likelihood Possible Evidence B
Phenobarbital (Luminal)

Theoretically, cola nut might reduce the effects of phenobarbital and increase the risk for convulsions.
Cola nut contains caffeine. Animal research suggests that caffeine can decrease the anticonvulsant activity of phenobarbital. However, this effect has not been reported in humans.

Likelihood Possible Evidence D
Phenylpropanolamine

Theoretically, phenylpropanolamine might increase the risk of hypertension, as well as the levels and adverse effects of the caffeine in cola nut.
Cola nut 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, cola nut might reduce the effects of phenytoin and increase the risk for convulsions.
Cola nut 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
Pioglitazone (Actos)

Theoretically, cola nut might increase the levels and clinical effects of pioglitazone.
Cola nut 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
Quinolone Antibiotics

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

Likelihood Probable Evidence B
Kola Nut Leaf Extract full monograph & all 41 interactions

CognatiQ33 drug types · 591 drugs

Ephedrine

Theoretically, concomitant use might increase the risk of stimulant adverse effects.
Coffee 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, coffee might decrease the vasodilatory effects of adenosine and interfere with its use prior to stress testing.
Coffee 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
Alendronate (Fosamax)

Coffee reduces alendronate bioavailability.
Separate coffee ingestion and alendronate administration by two hours. Coffee reduces alendronate bioavailability by 60%.

Likelihood Probable Evidence B
Anticoagulant/Antiplatelet Drugs

Theoretically, coffee may increase the risk of bleeding if used with anticoagulant or antiplatelet drugs.
Coffee contains caffeine. Caffeine is reported to have antiplatelet activity. Theoretically, the caffeine in coffee might increase the risk of bleeding when used concomitantly with these agents. However, this interaction has not been reported in humans. There is some evidence that caffeinated coffee might increase the fibrinolytic activity in blood.

Likelihood Unlikely Evidence D
Beta-Adrenergic Agonists

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

Likelihood Probable Evidence D
Cimetidine (Tagamet)

Theoretically, cimetidine might increase the effects and adverse effects of caffeine in coffee.
Coffee contains caffeine. Cimetidine can reduce caffeine clearance by 31% to 42%.

Likelihood Likely Evidence B
Clozapine (Clozaril)

Theoretically, coffee might increase the levels and adverse effects of clozapine and acutely exacerbate psychotic symptoms.
Coffee contains caffeine. 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 coffee.
Coffee contains caffeine. Oral contraceptive drugs can decrease caffeine clearance by 40% to 65%.

Likelihood Probable Evidence B
Dipyridamole (Persantine)

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

Likelihood Probable Evidence B
Diuretic Drugs

Theoretically, concomitant use might increase the risk of hypokalemia.
Coffee 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.
Coffee contains caffeine. Estrogen inhibits caffeine metabolism.

Likelihood Probable Evidence B
Fluvoxamine (Luvox)

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

Likelihood Probable Evidence B
Lamotrigine (Lamictal)

Coffee consumption can decrease the levels and clinical effects of lamotrigine.
A pharmacokinetic study in patients taking lamotrigine shows that consumption of coffee, both caffeinated and decaffeinated, can decrease the area under the concentration-time curve (AUC) and the peak plasma level (Cmax) of lamotrigine. Each additional cup of coffee reduced the AUC and Cmax by 4% and 3%, respectively. It is unclear whether this interaction is due to induction of lamotrigine metabolism or inhibition of lamotrigine absorption.

Likelihood Probable Evidence B
Levothyroxine (Synthroid, Others)

Coffee can reduce the absorption of levothyroxine.
In some patients, coffee can reduce levothyroxine absorption, possibly through the formation of non-absorbable complexes. A pharmacokinetic study in these patients found that 25-30 mL of espresso coffee consumed with levothyroxine tablets delayed the time to peak plasma levels by 38-43 minutes, reduced the peak plasma level (Cmax) by 19% to 36%, and reduced the area under the curve (AUC) by 27% to 36%. Coffee consumed one hour after levothyroxine did not affect absorption. It is not known whether this interaction occurs with other types of coffee. Tell patients to avoid drinking coffee at the same time that they take their levothyroxine, and for up to an hour afterwards.

Likelihood Possible Evidence B
Lithium

Theoretically, abrupt coffee withdrawal might increase the levels and adverse effects of lithium.
Coffee contains caffeine. Abrupt caffeine withdrawal can increase serum lithium levels. Two cases of lithium tremor that worsened with abrupt coffee withdrawal have been reported. There is also one case of a 2.8-fold increase in blood lithium levels after a patient taking lithium reduced his coffee consumption from 13-20 cups daily to 10 cups daily.

Likelihood Probable Evidence D
Monoamine Oxidase Inhibitors (Maois)

Theoretically, concomitant use might increase the risk of a hypertensive crisis.
Coffee 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 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.
Coffee 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
Pentobarbital (Nembutal)

Theoretically, coffee might reduce the effects of pentobarbital.
Coffee contains caffeine. Theoretically, caffeine might negate the hypnotic effects of pentobarbital.

Likelihood Possible Evidence B
Phenylpropanolamine

Theoretically, phenylpropanolamine might increase the risk of hypertension, as well as the levels and adverse effects of caffeine.
Coffee 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
Pioglitazone (Actos)

Theoretically, coffee might increase the levels and clinical effects of pioglitazone.
Coffee 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
Quinolone Antibiotics

Theoretically, quinolone antibiotics might increase the levels and adverse effects of caffeine.
Coffee contains caffeine. Concomitant use of caffeine and quinolones can decrease caffeine clearance and increase effects and risk of adverse effects.

Likelihood Probable Evidence B
Riluzole (Rilutek)

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

Likelihood Possible Evidence D
Stimulant Drugs

Theoretically, concomitant use might increase stimulant adverse effects.
Coffee 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 Probable Evidence C
Theophylline

Theoretically, coffee might increase the levels and adverse effects of theophylline.
Coffee contains caffeine, which can increase theophylline levels.

Likelihood Probable Evidence B
CognatiQ full monograph & all 33 interactions

Huperzia serrata Leaf Extract2 drug types · 219 drugs

Anticholinergic Drugs

In animal models, toothed clubmoss and huperzine A, an active constituent of toothed clubmoss, reversed cognitive deficits induced by scopolamine. Theoretically, concurrent use of anticholinergic drugs and toothed clubmoss might decrease the effectiveness of toothed clubmoss or the anticholinergic drug.
Some anticholinergic drugs include atropine, benztropine (Cogentin), biperiden (Akineton), procyclidine (Kemadrin), and trihexyphenidyl (Artane).

Likelihood Possible Evidence D
Cholinergic Drugs

Huperzine A, a constituent of toothed clubmoss, has demonstrated acetylcholinesterase inhibitory properties. Theoretically, concurrent use of toothed clubmoss with cholinergic drugs might have additive effects and increase the risk of cholinergic side effects.
Cholinergic drugs include bethanechol (Urecholine), donepezil (Aricept), echothiophate (Phospholine Iodide), edrophonium (Enlon, Reversol, Tensilon), neostigmine (Prostigmin), physostigmine (Antilirium), pyridostigmine (Mestinon, Regonol), succinylcholine (Anectine, Quelicin), and tacrine (Cognex).

Likelihood Possible Evidence D
Huperzia serrata Leaf Extract full monograph & interactions

L-Citrulline DL-Malate2 drug types · 178 drugs

Antihypertensive Drugs

Theoretically, concomitant use of L-citrulline with antihypertensive drugs might have additive effects and increase the chance of hypotension.
L-citrulline is converted to L-arginine, which can increase nitric oxide and cause vasodilation. However, a meta-analysis of 5 small clinical studies suggests that taking L-citrulline 3-6 grams daily for 1-8 weeks does not lower blood pressure when compared with control.

Likelihood Possible Evidence B
Phosphodiesterase-5 Inhibitors

Theoretically, concurrent use of phosphodiesterase-5 (PDE-5) inhibitors and L-citrulline might result in additive vasodilation.
L-citrulline is converted to L-arginine, which can increase nitric oxide and cause vasodilation. Theoretically, taking L-arginine with PDE-5 inhibitors might have additive vasodilatory and hypotensive effects. However, in studies evaluating the combined use of L-arginine and sildenafil for erectile dysfunction, hypotension was not reported.

Likelihood Possible Evidence D
L-Citrulline DL-Malate 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
The maker

Brand information

Manufacturer and brand details for BZRK Crystal Blue, from the product label.

Black Magic

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Name
Black Magic
Pharmacist Counseling Corner

BZRK Crystal Blue by Black Magic: Common Questions

Does BZRK Crystal Blue by Black Magic interact with any medications?
Yes. Based on its ingredients, BZRK Crystal Blue has a known interaction with 911 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?
BZRK Crystal Blue 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.
Does this have a lot of caffeine?
Yes. BZRK Crystal Blue contains caffeine from three sources: Caffeine Anhydrous, Caffeine, and CognatiQ (coffee extract), so you're getting a combined dose. If you're sensitive to stimulants or already consuming caffeine elsewhere, this could add up quickly. Check the label for total milligrams and talk to your pharmacist if you're unsure.
What is L-Tyrosine in this product supposed to do?
L-Tyrosine is an amino acid your body uses to make certain brain chemicals. It's effective for a rare genetic condition called PKU, and the evidence suggests it may help with cognitive function and memory, though athletic performance is less clearly supported.
Is this safe if I'm pregnant or breastfeeding?
Not enough safety data exists for most of the active ingredients during pregnancy and breastfeeding. L-Tyrosine and L-Citrulline have insufficient data — talk to your doctor or pharmacist for personalized advice. Caffeine should be limited during pregnancy and kept moderate while breastfeeding. Beta-alanine and Adhatoda vasaka are best avoided. Your pharmacist can help you decide.
What are those tingling sensations I might feel?
Beta-alanine (Beta-O) commonly causes pins-and-needles sensations (paresthesia) and skin flushing, usually starting on the scalp within 20 minutes and lasting about an hour. This is harmless and dose-dependent — it happens less at lower doses.
Can I take this if I'm on blood pressure medication?
No, not without checking first. L-Citrulline in this product can lower blood pressure further when combined with blood pressure medications, and the caffeine content is a stimulant that can work against those drugs. Talk to your pharmacist before adding it.
What does the Huperzia serrata in this product do?
We don't have effectiveness data on file for Huperzia serrata. You may want to ask the manufacturer what role they included it for, or talk to your pharmacist about what the ingredient is used for in supplement practice.

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.

BZRK Crystal Blue label
Go deeper

The Full Monographs Behind BZRK Crystal Blue’s Ingredients

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

Herb & supplement monograph

L-citrulline

Interacts with 178 drugs

L-citrulline is an amino acid that the body turns into L-arginine to help make nitric oxide, which relaxes blood vessels and may improve blood flow. It is popular for exercise performance an...

Read the full L-citrulline 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

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

Toothed Clubmoss

Interacts with 219 drugs

Toothed Clubmoss is a moss-like plant best known as the natural source of huperzine A, a compound studied mainly for memory and Alzheimer's disease. Some early research is promising, but the...

Read the full Toothed Clubmoss monograph → Herb & supplement monograph

Malabar Nut

Malabar nut (vasaka) is a traditional Ayurvedic herb used mostly for coughs and other breathing problems. Lab and animal studies suggest its compounds may help loosen mucus and relax airways...

Read the full Malabar Nut monograph → Herb & supplement monograph

Cola Nut

Interacts with 655 drugs

Cola nut is a caffeine-containing seed from West Africa used mainly as a natural stimulant for energy and alertness. Most of its effects come from caffeine, and strong human evidence for spe...

Read the full Cola Nut monograph → Herb & supplement monograph

Glycerol

Glycerol (glycerin) is a sweet, syrupy compound made naturally in the body and widely used in foods, skin products, and medicines. It is well established as a laxative and a skin and eye moi...

Read the full Glycerol 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

Coffee

Interacts with 591 drugs

Coffee is a widely consumed beverage made from roasted coffee beans, valued mainly for its caffeine, which boosts alertness and energy. For most healthy adults, moderate coffee intake is gen...

Read the full Coffee 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 →
Sources

Sources & How We Checked

BZRK Crystal Blue'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 620 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.

Tyrosine 4 references
  1. Meyer JS, Welch KM, Deshmukh VD, et al. Neurotransmitter precursor amino acids in the treatment of multi-infarct dementia and Alzheimer's disease. J Amer Geriat Soc 1977;25:289-98.
  2. DiPiro JT, Talbert RL, Yee GC, et al; eds. Pharmacotherapy: A pathophysiologic approach. 4th ed. Stamford, CT: Appleton & Lange, 1999.
  3. Wood DR, Reimherr FW, Wender PH. Amino acid precursors for the treatment of attention deficit disorder, residual type. Psychopharmacol Bull 1985;21:146-9.
  4. van Spronsen FJ, van Rijn M, Bekhof J. Phenylketonuria: tyrosine supplementation in phenylalanine-restricted diets. Am J Clin Nutr 2001;73:153-7. PubMed

See these in context on the Tyrosine monograph →

Caffeine 236 references
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  3. Carbo M, Segura J, De la Torre R, et al. Effect of quinolones on caffeine disposition. Clin Pharmacol Ther 1989;45:234-40. PubMed
  4. Healy DP, Polk RE, Kanawati L, et al. Interaction between oral ciprofloxacin and caffeine in normal volunteers. Antimicrob Agents Chemother 1989;33:474-8. PubMed
  5. Mester R, Toren P, Mizrachi I, et al. Caffeine withdrawal increases lithium blood levels. Biol Psychiatry 1995;37:348-50. PubMed
  6. Jefferson JW. Lithium tremor and caffeine intake: two cases of drinking less and shaking more. J Clin Psychiatry 1988;49:72-3.
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  9. Wakabayashi K, Kono S, Shinchi K, et al. Habitual coffee consumption and blood pressure: A study of self-defense officials in Japan. Eur J Epidemiol 1998;14:669-73. PubMed
  10. Hodgson JM, Puddey IB, Burke V, et al. Effects on blood pressure of drinking green and black tea. J Hypertens 1999;17:457-63. PubMed
  11. Rapuri PB, Gallagher JC, Kinyamu HK, Ryschon KL. Caffeine intake increases the rate of bone loss in elderly women and interacts with vitamin D receptor genotypes. Am J Clin Nutr 2001;74:694-700. PubMed
  12. The National Toxicology Program (NTP). Caffeine. Center for the Evaluation of Risks to Human Reproduction (CERHR). Available at: http://cerhr.niehs.nih.gov/common/caffeine.html.
  13. Klebanoff MA, Levine RJ, DerSimonian R, et al. Maternal serum paraxanthine, a caffeine metabolite, and the risk of spontaneous abortion. N Engl J Med 1999;341:1639-44. PubMed
  14. Eskenazi B. Caffeine—filtering the facts. N Engl J Med 1999;341:1688-9. PubMed
  15. Fernandes O, Sabharwal M, Smiley T, et al. Moderate to heavy caffeine consumption during pregnancy and relationship to spontaneous abortion and abnormal fetal growth: a meta-analysis. Reprod Toxicol 1998;12:435-44. PubMed
  16. Pollock BG, Wylie M, Stack JA, et al. Inhibition of caffeine metabolism by estrogen replacement therapy in postmenopausal women. J Clin Pharmacol 1999;39:936-40. PubMed
  17. Nurminen ML, Niittynen L, Korpela R, Vapaatalo H. Coffee, caffeine and blood pressure: a critical review. Eur J Clin Nutr 1999;53:831-9. PubMed
  18. Dews PB, Curtis GL, Hanford KJ, O'Brien CP. The frequency of caffeine withdrawal in a population-based survey and in a controlled, blinded pilot experiment. J Clin Pharmacol 1999;39:1221-32. PubMed
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  21. Hagg S, Spigset O, Mjorndal T, Dahlqvist R. Effect of caffeine on clozapine pharmacokinetics in healthy volunteers. Br J Clin Pharmacol 2000;49:59-63. PubMed
  22. Tobias JD. Caffeine in the treatment of apnea associated with respiratory syncytial virus infection in neonates and infants. South Med J 2000;93:297-304. DOI
  23. Watson JM, Jenkins EJ, Hamilton P, et al. Influence of caffeine on the frequency and perception of hypoglycemia in free-living patients with type 1 diabetes. Diabetes Care 2000;23:455-9. PubMed
  24. Lloyd T, Johnson-Rollings N, Eggli DF, et al. Bone status among postmenopausal women with different habitual caffeine intakes: a longitudinal investigation. J Am Coll Nutr 2000;19:256-61. PubMed
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  26. Sinclair CJ, Geiger JD. Caffeine use in sports. A pharmacological review. J Sports Med Phys Fitness 2000;40:71-9.
  27. Haller CA, Benowitz NL. Adverse cardiovascular and central nervous system events associated with dietary supplements containing ephedra alkaloids. N Engl J Med 2000;343:1833-8. PubMed
  28. Ali M, Afzal M. A potent inhibitor of thrombin stimulated platelet thromboxane formation from unprocessed tea. Prostaglandins Leukot Med 1987;27:9-13. PubMed
  29. Ardlie NG, Glew G, Schultz BG, Schwartz CJ. Inhibition and reversal of platelet aggregation by methyl xanthines. Thromb Diath Haemorrh 1967;18:670-3. DOI
  30. Ferrini RL, Barrett-Connor E. Caffeine intake and endogenous sex steroid levels in postmenopausal women. The Rancho Bernardo Study. Am J Epidemiol 1996:144:642-4. PubMed
  31. Avisar R, Avisar E, Weinberger D. Effect of coffee consumption on intraocular pressure. Ann Pharmacother 2002;36:992-5.. PubMed
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  33. Horner NK, Lampe JW. Potential mechanisms of diet therapy for fibrocystic breast conditions show inadequate evidence of effectiveness. J Am Diet Assoc 2000;100:1368-80. PubMed
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  36. Massey LK. Is caffeine a risk factor for bone loss in the elderly? Am J Clin Nutr 2001;74:569-70. PubMed
  37. Dreher HM. The effect of caffeine reduction on sleep quality and well-being in persons with HIV. J Psychosom Res 2003;54:191-8.. PubMed
  38. Kockler DR, McCarthy MW, Lawson CL. Seizure activity and unresponsiveness after hydroxycut ingestion. Pharmacotherapy 2001;21:647-51.. PubMed
  39. Schechter MD, Timmons GD. Objectively measured hyperactivity--II. Caffeine and amphetamine effects. J Clin Pharmacol 1985;25:276-80.. PubMed
  40. Nix D, Zelenitsky S, Symonds W, et al. The effect of fluconazole on the pharmacokinetics of caffeine in young and elderly subjects. Clin Pharmacol Ther 1992;51:183. DOI
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  42. Massey LK, Whiting SJ. Caffeine, urinary calcium, calcium metabolism and bone. J Nutr 1993;123:1611-4. PubMed
  43. Nawrot P, Jordan S, Eastwood J, et al. Effects of caffeine on human health. Food Addit Contam 2003;20:1-30. PubMed
  44. May DC, Jarboe CH, VanBakel AB, Williams WM. Effects of cimetidine on caffeine disposition in smokers and nonsmokers. Clin Pharmacol Ther 1982;31:656-61. PubMed
  45. Abernethy DR, Todd EL. Impairment of caffeine clearance by chronic use of low-dose oestrogen-containing oral contraceptives. Eur J Clin Pharmacol 1985;28:425-8. PubMed
  46. Brown NJ, Ryder D, Branch RA. A pharmacodynamic interaction between caffeine and phenylpropanolamine. Clin Pharmacol Ther 1991;50:363-71. PubMed
  47. Sanderink GJ, Bournique B, Stevens J, et al. Involvement of human CYP1A isoenzymes in the metabolism and drug interactions of riluzole in vitro. Pharmacol Exp Ther 1997;282:1465-72. DOI
  48. Wahllander A, Paumgartner G. Effect of ketoconazole and terbinafine on the pharmacokinetics of caffeine in healthy volunteers. Eur J Clin Pharmacol 1989;37:279-83. PubMed
  49. Carrillo JA, Benitez J. Clinically significant pharmacokinetic interactions between dietary caffeine and medications. Clin Pharmacokinet 2000;39:127-53. PubMed
  50. Underwood DA. Which medications should be held before a pharmacologic or exercise stress test? Cleve Clin J Med 2002;69:449-50. PubMed
  51. Aqel RA, Zoghbi GJ, Trimm JR, et al. Effect of caffeine administered intravenously on intracoronary-administered adenosine-induced coronary hemodynamics in patients with coronary artery disease. Am J Cardiol 2004;93:343-6. PubMed
  52. Zheng XM, Williams RC. Serum caffeine levels after 24-hour abstention: clinical implications on dipyridamole (201)Tl myocardial perfusion imaging. J Nucl Med Technol 2002;30:123-7.
  53. Institute of Medicine. Caffeine for the Sustainment of Mental Task Performance: Formulations for Military Operations. Washington, DC: National Academy Press, 2001. Available at: http://books.nap.edu/books/0309082587/html/index.html. DOI
  54. Dews PB, O'Brien CP, Bergman J. Caffeine: behavioral effects of withdrawal and related issues. Food Chem Toxicol 2002;40:1257-61. PubMed
  55. Beach CA, Mays DC, Guiler RC, et al. Inhibition of elimination of caffeine by disulfiram in normal subjects and recovering alcoholics. Clin Pharmacol Ther 1986;39:265-70. PubMed
  56. Juliano LM, Griffiths RR. A critical review of caffeine withdrawal: empirical validation of symptoms and signs, incidence, severity, and associated features. Psychopharmacology (Berl) 2004;176:1-29. PubMed
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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.

© 2021 Therapeutic Research Center, LLC

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