Major interaction on record — check this product against your medications before combining. Based on 4 of 5 ingredients. Check your meds →
Dietary supplement

Formulean Ingredients & Drug Interactions

by The Vitamin Shoppe Next Step

Formulean label
See full label image
Capsule 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 Formulean 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

Formulean is a dietary supplement by The Vitamin Shoppe Next Step with 5 active ingredients. Its ingredients are commonly taken for depression and mood, skin condition vitiligo, pain conditions.Based on those ingredients, 1,007 medications have a known interaction with it, the most serious rated major. The ingredients most likely to interact are Citrimax Garcinia cambogia extract, Guarana extract, L-Carnipure. Use the checker below to test your specific medication, or read the full HelloPharmacist Interaction Report.

Jump to a section

Check Your Meds Against Formulean by The Vitamin Shoppe Next Step

Ask about any prescription or over-the-counter medication and we check it for interactions with Formulean by The Vitamin Shoppe Next Step — and tell you which ingredient is responsible.

Pharmacist-reviewed data Checks every ingredient Answer in seconds
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HelloPharmacist Scorecard of Formulean by The Vitamin Shoppe Next Step

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 30, 2026

What’s inside

Full disclosure
Ingredient Transparency · database check
Full

Every active ingredient lists its own amount on the label.

Why this rating?
  • The label discloses an exact amount for 5 of its 5 active ingredients.
  • No proprietary blends here — you can verify the dose of every single component.

Formulean contains five active ingredients. L-phenylalanine is an amino acid that the body uses to make neurotransmitters and other compounds; the product supplies it in supplement form.

Chromax Chromium is a chromium compound meant to support nutrient metabolism. Guarana extract is a plant ingredient naturally high in caffeine, included for its stimulant properties.

Citrimax Garcinia cambogia extract provides hydroxycitric acid (HCA), a compound from the garcinia fruit traditionally used in weight management products. L-Carnipure is a branded form of L-carnitine, an amino acid that plays a role in energy production in cells.

The capsule also contains inactive ingredients—microcrystalline cellulose, gelatin, silicon dioxide, and magnesium stearate—which serve as fillers, binders, and flow agents.

Does it work?

Not established
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
Not established

The graded evidence we hold for these ingredients covers different conditions than the ones this product is marketed for, so there's no established rating for its stated use.

Why this rating?
  • The label markets this product for: supports healthy body weight management.
  • We looked for evidence on: Obesity, Metabolic syndrome, Exercise-induced muscle damage, Exercise-induced muscle soreness, Athletic performance, Weight loss — and 2 related terms.
  • The closest evidence on file: Phenylalanine is rated "Insufficient Reliable Evidence To Rate" for Obesity (Natural Medicines).
  • Also on file: Garcinia is rated "Insufficient Reliable Evidence To Rate" for Athletic performance, Obesity.
  • Also on file: Guarana is rated "Insufficient Reliable Evidence To Rate" for Athletic performance, Obesity.

Evidence for L-phenylalanine in this product is mixed: it's rated possibly effective for vitiligo but possibly ineffective for ADHD. For alcohol use disorder and multiple sclerosis, the evidence is insufficient to rate it either way.

Guarana extract shows insufficient evidence to rate for cancer-related anorexia, anxiety, athletic performance, cancer-related fatigue, and chemotherapy-related fatigue. Garcinia cambogia extract also lacks sufficient evidence to rate for athletic performance, nonalcoholic fatty liver disease, hyperlipidemia, and obesity.

L-carnitine is rated effective for L-carnitine deficiency and possibly effective for high cholesterol, congestive heart failure, and angina. We hold no effectiveness data on Chromax Chromium.

The evidence, ingredient by ingredient Phenylalanine Guarana Garcinia L-carnitine

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 4 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.

L-phenylalanine is generally well tolerated in food amounts, but supplement doses carry risks—especially for people with phenylketonuria (PKU), a genetic condition where the body can't process phenylalanine safely. Avoid supplement doses during pregnancy and while breastfeeding due to lack of safety data.

Common side effects include anxiety, constipation, headache, heartburn, insomnia, and nausea. Guarana is high in caffeine and generally tolerated in small amounts, but the data advises avoiding it during pregnancy and limiting or avoiding it while breastfeeding because caffeine passes into breast milk.

Common side effects are stomach burning and nausea; larger doses may cause insomnia, nervousness, restlessness, dizziness, tremors, and anxiety. Garcinia cambogia is generally well tolerated short-term, but rare reports of liver injury warrant caution; avoid it during pregnancy and breastfeeding due to insufficient safety data.

Common side effects are diarrhea, gastrointestinal discomfort, headache, and nausea; rare serious effects include liver damage and mania. L-carnitine is generally well tolerated, though high doses can cause stomach upset and a fish-like body odor.

Avoid high doses during pregnancy; breastfeeding safety is not well studied, so talk with your pharmacist or doctor.

Side effects, ingredient by ingredient Phenylalanine Guarana Garcinia L-carnitine

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 — Phenylalanine, Garcinia, Guarana, L-carnitine.
  • 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: 1,008 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 Formulean, double-check with your doctor or pharmacist if you take levodopa (for Parkinson disease)—this is a major interaction. Also check if you take seizure medications (valproate, felbamate, carbamazepine), blood thinners (warfarin or other anticoagulants or antiplatelet drugs), antidiabetes drugs, serotonergic antidepressants, thyroid hormone, muscle relaxants (baclofen), monoamine oxidase inhibitors (older antidepressants), ephedrine, clozapine, fluvoxamine, disulfiram, or dipyridamole.

These represent the documented moderate-to-major interactions across the product's ingredients.

Check your own medication Run your meds through the checker above

The bottom line

Scorecard at a glanceFully disclosed formula with no established evidence rating for its marketed use. Major medication interactions have been identified, and safety information is well characterized.

Formulean is a multi-ingredient weight-management product that may be worth considering if you're not taking medications for Parkinson disease, seizures, blood pressure, blood sugar, or thyroid function, and if you don't take blood thinners or older antidepressants. Its effectiveness for weight loss isn't well established in our data.

The combination of L-phenylalanine and high-caffeine guarana extract, plus the rare liver risks from garcinia, means you should talk it over with your doctor or pharmacist before starting—especially if you're pregnant, breastfeeding, have PKU, or take any regular medications.

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

Assessment coverage: 4 of 5 active ingredients matched to our full ingredient reviews (monographs). Based on the product label dated Jan 25, 2016.

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 Formulean, straight from the product label.

Brand The Vitamin Shoppe Next Step
Barcode (UPC) 766536028979
Net contents 90 Capsule(s)
Market status On market
Date entered into DSLD Jan 25, 2016
DSLD ID 55376
Product type Other Combinations
Supplement form Capsule
Dietary claims / uses All Other, Structure/Function
Intended target group(s) Adult (18 - 50 Years), Dairy Free
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 Formulean by The Vitamin Shoppe Next Step, 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:
3 Capsule(s)
Maximum serving Sizes:
3 Capsule(s)
Servings per container
30
UPC/BARCODE
766536028979
IngredientAmount% DV
L-Phenylalanine250 mg--
Chromax Chromium200 mcg167%
Guarana extract909 mg--
Citrimax Garcinia cambogia extract500 mg--
L-Carnipure100 mg--

Other ingredients: Microcrystalline Cellulose, Gelatin, Silicon Dioxide, Magnesium Stearate

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

Supports healthy body weight

This product may support a weight management or diet program that includes regular exercise and a calorie restricted diet.

Visit www.vitaminshoppe.com or call 1-800-223-1216 for more information and to reorder.

I want to manage my weight loss and feel energized

FDA Statement of Identity

Dietary Supplement

Formulation

Does not contain: Yeast, Wheat, Salt, Soy, Dairy, Citrus, Fish, Preservatives, Artificial Colors or Flavors.

Precautions

NOT INTENDED FOR USE BY PERSONS UNDER THE AGE OF 18.

Please note: Guarana Extract contains caffeine and should not be taken by those wishing to eliminate caffeine from their diet.

Warning: Do not use if you are pregnant, nursing or if you are at risk or being treated for high blood pressure, heart disease, stroke, nervousness or anxiety. Do not use this supplement if you are taking MAO inhibitors (some antidepressants).

Consult your physician before use if you are diabetic. Do not use if you have the genetic disease PKU or existing pigmented malignant melanoma type skin cancer. Discontinue use and consult your healthcare professional if dizziness, sleeplessness, tremors, nervousness, headache, heart palpitations or tingling sensations occur.

Tamper evident Do not use if outer seal is broken or missing.

Keep out of reach of children.

Suggested/Recommended/Usage/Directions

Directions:As a dietary supplement, take three (3) capsules before breakfast or morning workout. Also take three (3) capsules before afternoon and evening meals. Do not exceed nine capsules daily. Taking more than the recommended amount will not improve results and may cause adverse reactions listed in the warning below. Begin use with one-third the recommended dose (one capsule three times per day) to assess your tolerance. For best results, use as part of a low-fat diet and exercise program.

FDA Disclaimer Statement

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

Formula

Please note: Guarana Extract contains caffeine and should not be taken by those wishing to eliminate caffeine from their diet.

Powered by Citrimax, L-Carnitine, and Guarana

Brand IP Statement(s)

Chromax is a registered trademark of Nutrition 21. L-Carnipure offers purest L-Carnitine and is a trademark of Lonza Ltd, Switzerland. CitriMax is a trademark of InterHealth N.I.

Storage

Store in a cool, dry place.

Seals/Symbols

Citrimax

General

Item No. VS-2897 1972371 BP 52

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

See for yourself

Formulean by The Vitamin Shoppe Next Step label

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

Formulean 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 Formulean by The Vitamin Shoppe Next Step

These are the 5 active ingredients this product is made of. Select any to open its full monograph.

Serving size3 Capsule(s) Dosage formCapsule Servings per container30 Amounts shown are per serving.

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

L-Phenylalanine

Interacts with
16 drugs
250 mg per serving

Phenylalanine is an essential amino acid the body uses to make brain chemicals like dopamine and norepinephrine. Some people take it for mood, vitilig...

L-Phenylalanine monograph & interactions

Chromax Chromium

200 mcg per serving Form: Chromium Picolinate

Guarana extract

Interacts with
655 drugs
909 mg per serving Form: Caffeine

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-te...

Guarana extract monograph & interactions

Citrimax Garcinia cambogia extract

Interacts with
704 drugs
500 mg per serving Form: (-) Hydroxycitric Acid

Garcinia is a tropical fruit whose rind contains hydroxycitric acid (HCA), widely marketed for weight loss and appetite control. The scientific eviden...

Citrimax Garcinia cambogia extract monograph & interactions

L-Carnipure

Interacts with
19 drugs
100 mg per serving Form: L-Carnitine Tartrate

L-carnitine is a compound your body makes naturally and also gets from foods like meat. It helps cells turn fat into energy, and supplements are most...

L-Carnipure monograph & interactions

Other (inactive) ingredients: Microcrystalline Cellulose, Gelatin, Silicon Dioxide, Magnesium Stearate. These complete the product’s ingredient list but are not active constituents.

Interaction report

Formulean by The Vitamin Shoppe Next Step Drug Interactions

Want to check YOUR meds against Formulean?

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

 Go to the checker
1,007Drugs
13 Major 931 Moderate 63 Minor

Ingredients driving the most interactions

Citrimax Garcinia cambogia extract 704
Guarana extract 655
L-Carnipure 19
L-Phenylalanine 16

Individual Drug Interactions

The ingredients in Formulean interact with 1,007 drugs. Click any drug to see the details.

4 of the 5 ingredients in Formulean interact with drugs. Each result below shows which ingredient is responsible. Citrimax Garcinia cambogia extract Guarana extract L-Carnipure L-Phenylalanine

Each ingredient & the kinds of drugs it affects

For each ingredient in Formulean 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.

Citrimax Garcinia cambogia extract4 drug types · 704 drugs

Anticoagulant/Antiplatelet Drugs

Theoretically, hydroxycitric acid (HCA), the main active ingredient in garcinia, might increase the risk of bleeding when used with antiplatelet or anticoagulant drugs.
HCA inhibits platelet aggregation in vitro. The inhibitory effect seems to be greater in platelets extracted from diabetic subjects than non-diabetic subjects.

Likelihood Possible Evidence D
Antidiabetes Drugs

Theoretically, hydroxycitric acid (HCA), the main active ingredient in garcinia, might have additive effects with antidiabetes drugs and increase the risk of hypoglycemia.
HCA reduces fasting and postprandial blood glucose levels in animal models, theoretically by delaying glucose absorption. This effect has not been reported in humans.

Likelihood Possible Evidence D
Hepatotoxic Drugs

Theoretically, concomitant use with other potentially hepatotoxic drugs might increase the risk of developing liver damage.
There have been reports of acute hepatitis with elevated liver enzymes associated with garcinia, when taken alone or in combination with other ingredients. Case reports collected from the Drug Induced Liver Injury Network suggest this risk may be greater in people who carry the HLA B*35:01 allele.

Likelihood Possible Evidence D
Serotonergic Drugs

Theoretically, combining garcinia with other serotonergic drugs might increase the risk of serotonergic side effects, including serotonin syndrome.
In one report, a patient experienced serotonin syndrome after taking garcinia extract (60% hydroxycitric acid) 1000 mg daily in combination with escitalopram 20 mg, which had been taken for a year. The patient was switched to sertraline 50 mg daily and again experienced serotonin syndrome.

Likelihood Possible Evidence D
Citrimax Garcinia cambogia extract full monograph & interactions

Guarana 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
Guarana extract full monograph & all 41 interactions

L-Carnipure3 drug types · 19 drugs

Acenocoumarol (Sintrom)

Theoretically, L-carnitine might increase the anticoagulant effects of acenocoumarol.
L-carnitine might enhance the anticoagulant effects of acenocoumarol, an oral anticoagulant similar to warfarin, but shorter-acting. There are at least two case reports of INR elevation with concomitant use. In one case, a 33-year-old male with a previously stable INR had an elevated INR of 4.65 after L-carnitine was started and continued for 10 weeks. INR normalized after discontinuation of the L-carnitine-containing product.

Likelihood Possible Evidence D
Thyroid Hormone

Theoretically, L-carnitine might decrease the effectiveness of thyroid hormone replacement.
L-carnitine appears to act as a peripheral thyroid hormone antagonist by inhibiting entry of thyroid hormone into the nucleus of cells. Taking L-carnitine also seems to diminish some of the symptoms of hyperthyroidism.

Likelihood Probable Evidence B
Warfarin (Coumadin)

Theoretically, L-carnitine might increase the anticoagulant effects of warfarin.
L-carnitine might increase the anticoagulant effects of acenocoumarol, a shorter-acting oral anticoagulant similar to warfarin. There is not enough information to know whether this interaction occurs with L-carnitine and warfarin.

Likelihood Possible Evidence D
L-Carnipure full monograph & interactions

L-Phenylalanine3 drug types · 16 drugs

Levodopa

Phenylalanine, especially in high doses, can reduce the effectiveness of levodopa.
Phenylalanine competes with levodopa for carrier-mediated transport into the brain. The resulting reduction in levels of levodopa in the brain can exacerbate tremor, rigidity, and the "on-off" phenomenon in patients with Parkinson disease.

Likelihood Probable Evidence B
Baclofen

Concomitant intake of phenylalanine may reduce the intestinal absorption of baclofen.
Phenylalanine and baclofen share the same intestinal carrier for absorption; phenylalanine competitively inhibits the absorption of baclofen, reducing its plasma levels.

Likelihood Possible Evidence D
Monoamine Oxidase Inhibitors (Maois)

Theoretically, concomitant use of L-phenylalanine and non-selective MAOIs might increase the risk of hypertensive crisis.
L-phenylalanine is metabolized to tyrosine. Some evidence suggests that L-phenylalanine, given with the non-selective MAOI pargyline, might prevent the elimination of tyramine, increasing the risk of hypertensive crisis. However, this was not reported in a small number of patients when using L-phenylalanine with the partially selective MAO-B inhibitor, selegiline.

Likelihood Possible Evidence D
L-Phenylalanine full monograph & interactions
The maker

Brand information

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

The Vitamin Shoppe Next Step

See all The Vitamin Shoppe Next Step products
Name
Vitamin Shoppe, Inc.
City
Secaucus
State
NJ
ZipCode
07094
Phone Number
1-800-223-1216
Web Address
www.vitaminshoppe.com
Pharmacist Counseling Corner

Formulean by The Vitamin Shoppe Next Step: Common Questions

Does Formulean by The Vitamin Shoppe Next Step interact with any medications?
Yes. Based on its ingredients, Formulean has a known interaction with 1,007 medications, including 13 rated major. Use the checker to see how it interacts with a specific drug.
How can one product interact with so many drugs?
Formulean contains 5 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.
Can I take Formulean if I'm pregnant or breastfeeding?
No—the data advises against supplement doses of L-phenylalanine during pregnancy and while breastfeeding. Garcinia cambogia also lacks enough safety data, so it's best avoided in both. Guarana's high caffeine content makes it unsafe in pregnancy and best limited or avoided while breastfeeding. Talk with your doctor or pharmacist for personalized advice.
What's in Formulean, and does it have fillers?
It has five active ingredients: L-phenylalanine, Chromax Chromium, guarana extract, garcinia cambogia extract, and L-carnitine. It also contains inactive ingredients—microcrystalline cellulose, gelatin, silicon dioxide, and magnesium stearate—which are standard fillers and binders used in capsules.
I have phenylketonuria (PKU). Can I take this?
No—the data specifically cautions against supplement doses of L-phenylalanine for people with PKU. Since this product contains L-phenylalanine, you should avoid it. Talk with your doctor or pharmacist about alternatives.
Does this product actually work for weight loss?
Our data doesn't establish it—garcinia cambogia has insufficient evidence to rate for obesity, and the other ingredients also lack reliable effectiveness data for weight management. Don't expect it to be a proven weight-loss aid based on the evidence we hold.
What side effects should I expect?
Common ones include anxiety, insomnia, headache, heartburn, nausea, constipation, diarrhea, and stomach discomfort—largely from the L-phenylalanine and high caffeine content. Guarana may also cause dizziness and nervousness, and garcinia may cause diarrhea or gastrointestinal discomfort. A fish-like body odor has been reported with L-carnitine at higher doses.
Why does this product interact with so many medications?
L-phenylalanine, guarana (caffeine), and L-carnitine each interact with different drug classes—seizure meds, blood thinners, thyroid drugs, antidepressants, and others—because they affect how the body absorbs, metabolizes, or responds to those drugs. When you combine multiple active ingredients, the total number of affected medications adds up quickly.

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.

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Go deeper

The Full Monographs Behind Formulean’s Ingredients

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

Herb & supplement monograph

Phenylalanine

Interacts with 16 drugs

Phenylalanine is an essential amino acid the body uses to make brain chemicals like dopamine and norepinephrine. Some people take it for mood, vitiligo, or pain, but the evidence is mostly l...

Read the full Phenylalanine 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 → Herb & supplement monograph

Garcinia

Interacts with 704 drugs

Garcinia is a tropical fruit whose rind contains hydroxycitric acid (HCA), widely marketed for weight loss and appetite control. The scientific evidence is weak and mixed, with most studies...

Read the full Garcinia monograph → Herb & supplement monograph

L-carnitine

Interacts with 19 drugs

L-carnitine is a compound your body makes naturally and also gets from foods like meat. It helps cells turn fat into energy, and supplements are most clearly useful for people with a true ca...

Read the full L-carnitine monograph →
Sources

Sources & How We Checked

Formulean'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 222 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.

Phenylalanine 23 references
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  3. Silkaitis RP, Mosnaim AD. Pathways linking L-phenylalanine and 2-phenylethylamine with p-tyramine in rabbit brain. Brain Res 1976;114:105-15.
  4. Lehmann WD, Theobald N, Fischer R, Heinrich HC. Stereospecificity of phenylalanine plasma kinetics and hydroxylation in man following oral application of a stable isotope-labelled pseudo-racemic mixture of L- and D-phenylalanine. Clin Chim Acta 1983;128 PubMed
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  8. Nutt JG, Woodward WR, Hammerstad JP, et al. The "on-off" phenomenon in Parkinson's disease. Relation to levodopa absorption and transport. N Engl J Med 1984;310:483-8. PubMed
  9. Baruzzi A, Contin M, Riva R, et al. Influence of meal ingestion time on pharmacokinetics of orally administered levodopa in parkinsonian patients. Clin Neuropharmacol 1987;10:527-37. PubMed
  10. Juncos JL, Fabbrini G, Mouradian MM, et al. Dietary influences on the antiparkinsonian response to levodopa. Arch Neurol 1987;44:1003-5. PubMed
  11. Eriksson T, Granerus AK, Linde A, et al. "On-off" phenomenon in Parkinson's disease: relationship between dopa and other large neutral amino acids in plasma. Neurology 1988;38:1245-8. PubMed
  12. Baker GB, Bornstein RA, Rouget AC, et al. Phenylethylaminergic mechanisms in attention-deficit disorder. Biol Psychiatry 1991;29:15-22.. PubMed
  13. Wood DR, Reimherr FW, Wender PH. Treatment of attention deficit disorder with DL-phenylalanine. Psychiatry Res 1985;16:21-6.. PubMed
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  16. Cejudo-Ferragud, E., Nacher, A., Polache, A., Cercos-Fortea, T., Merino, M., and Casabo, V. G. Evidence of competitive inhibition for the intestinal absorption of baclofen by phenylalanine. Int J of Pharm (Amsterdam) 1996;132:63-69. DOI
  17. Fischer, E., Heller, B., Nachon, M., and Spatz, H. Therapy of depression by phenylalanine. Preliminary note. Arzneimittelforschung. 1975;25(1):132.
  18. Beckmann, H., Strauss, M. A., and Ludolph, E. Dl-phenylalanine in depressed patients: an open study. J.Neural Transm. 1977;41(2-3):123-134. PubMed
  19. Sabelli, H. C., Fawcett, J., Gusovsky, F., Javaid, J. I., Wynn, P., Edwards, J., Jeffriess, H., and Kravitz, H. Clinical studies on the phenylethylamine hypothesis of affective disorder: urine and blood phenylacetic acid and phenylalanine dietary supplem
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  21. Kravitz, H. M., Sabelli, H. C., and Fawcett, J. Dietary supplements of phenylalanine and other amino acid precursors of brain neuroamines in the treatment of depressive disorders. J Am Osteopath.Assoc 1984;84(1 Suppl):119-123. DOI
  22. Mann, J., Peselow, E. D., Snyderman, S., and Gershon, S. D-phenylalanine in endogenous depression. Am.J.Psychiatry 1980;137(12):1611-1612. PubMed
  23. Katoulis AC, Alevizou A, Bozi E, et al. A randomized, double-blind, vehicle-controlled study of a preparation containing undecylenoyl phenylalanine 2% in the treatment of solar lentigines. Clin Exp Dermatol 2010;35(5):473-6. PubMed

See these in context on the Phenylalanine monograph →

Guarana 114 references
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