Major interaction on record — check this product against your medications before combining. Based on 14 of 20 ingredients. Check your meds →
Dietary supplement

Free-Form Amino Acids Ingredients & Drug Interactions

by Ecological Formulas

Free-Form Amino Acids label
See full label image
Powder Category: Amino Acid/protein
Most serious interaction: Major
Clinical methodology reviewed by · Updated Sep 16, 2026 · Label data from the NIH DSLD
What is this page for?

First and foremost: checking Free-Form Amino Acids 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

Free-Form Amino Acids is a dietary supplement by Ecological Formulas with 20 active ingredients. Its ingredients are commonly taken for high blood pressure, erectile dysfunction, athletic performance.Based on those ingredients, 481 medications have a known interaction with it, the most serious rated major. The ingredients most likely to interact are L-Arginine, L-Citrulline, L-Cysteine. Use the checker below to test your specific medication, or read the full HelloPharmacist Interaction Report.

Jump to a section

Check Your Meds Against Free-Form Amino Acids by Ecological Formulas

Ask about any prescription or over-the-counter medication and we check it for interactions with Free-Form Amino Acids by Ecological Formulas — and tell you which ingredient is responsible.

Pharmacist-reviewed data Checks every ingredient Answer in seconds
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HelloPharmacist Scorecard of Free-Form Amino Acids by Ecological Formulas

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

Low disclosure
Ingredient Transparency · database check
Low

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

Why this rating?
  • The label discloses an exact amount for 0 of its 20 active ingredients.
  • “Amino Acids” is listed as a grouped ingredient — the label gives one combined amount (655 mg) without saying how much of each component you get.
  • “Essential Amino Acids” is listed as a grouped ingredient — the label gives one combined amount (345 mg) without saying how much of each component you get.

This powder contains 20 amino acids—the building blocks your body uses to make proteins and other compounds. The active ingredients include both essential amino acids (ones your body cannot make and must get from food or supplements) and non-essential amino acids (ones your body can produce).

L-arginine, L-citrulline, L-methionine, L-proline, L-aspartic acid, L-histidine, L-threonine, L-lysine, L-tyrosine, L-glutamine, L-glycine, L-alanine, L-cysteine, and L-serine are among the named components; the product also contains L-leucine, L-isoleucine, L-valine, L-glutamic acid, L-cystine, and L-asparagine. There are no inactive ingredients listed.

Does it work?

Moderate 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
Moderate

Some clinical evidence supports this product's ingredients for its stated purpose, but it isn't conclusive.

Why this rating?
  • The label markets this product for: amino acid supplementation for allergic individuals.
  • We looked for evidence on: Atopic dermatitis (eczema), Allergic rhinitis (hay fever), Athletic performance, Cognitive function, Fatigue, Herpes labialis (cold sores) — and 4 related terms.
  • The strongest evidence on file: Lysine is rated "Possibly Effective" for Herpes labialis (cold sores) (Natural Medicines).
  • Also on file: Tyrosine is rated "Possibly Effective" for Cognitive function.
  • Also on file: L-citrulline is rated "Possibly Effective" for Athletic performance.

The evidence for most of these amino acids is limited or mixed. L-glutamine is rated effective for sickle cell disease and possibly effective for HIV/AIDS-related wasting and recovery after surgery or critical illness.

L-tyrosine is effective for phenylketonuria (PKU) and possibly effective for cognitive function and memory. L-lysine is possibly effective for cold sores.

L-serine and L-glycine are each possibly effective for schizophrenia. For most other claimed uses—athletic performance, muscle strength, fatigue, bone health, wound healing—the evidence we hold is insufficient to rate them, meaning it's not yet established whether these amino acids work for those purposes.

Talk with your doctor or pharmacist about what the science supports for your specific goal.

The evidence, ingredient by ingredient L-arginine L-citrulline Proline Aspartic Acid Tyrosine Glutamine Glycine Alpha-alanine

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 14 matched ingredients.
  • Pregnancy & breastfeeding safety ratings cover 14 of 14.
  • General safety write-ups exist for 14 of 14.
  • Remember: this measures how much safety information exists. Thin data is not the same as being safe.

Most of these amino acids are generally well tolerated at typical food-level amounts. L-arginine is often well tolerated short-term but can lower blood pressure and requires medical supervision for self-treatment.

L-citrulline is generally well tolerated in healthy adults, though long-term safety hasn't been fully studied. Common mild side effects across the ingredients include abdominal pain, bloating, nausea, diarrhea, headache, and heartburn.

L-serine at very high doses (above 25 grams) can cause reversible eye movement problems (nystagmus) or seizures. L-glutamine may rarely trigger mania or hypomania in people with bipolar disorder.

For pregnancy and breastfeeding: L-methionine and L-glutamine are rated likely safe; L-arginine is rated possibly safe in pregnancy but has no lactation data; L-citrulline, L-threonine, L-lysine, L-tyrosine, L-glycine, and L-serine have insufficient data and are best avoided unless your doctor advises otherwise. L-aspartic acid is rated possibly unsafe in pregnancy and lactation.

For ingredients we could not check (L-leucine, L-isoleucine, L-valine, L-glutamic acid, L-cystine, L-asparagine), safety data are not on file.

Side effects, ingredient by ingredient L-arginine L-citrulline Proline Aspartic Acid Tyrosine Glutamine Glycine Alpha-alanine

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?
  • 8 of the 14 matched ingredients can interact with medications — Lysine, L-arginine, Glutamine, Tyrosine, Glycine, among others.
  • The most serious interaction on file is rated Major.
  • Some involve high-stakes drug classes: anticoagulant / antiplatelet drugs; seizure medications; diabetes medications; Parkinson's medications.
  • For scale: 481 individual medications appear in the full list. A big number alone doesn't make a product dangerous — what matters is whether YOUR medication is on it, so run yours through the interaction checker on this page.

Before taking this product, double-check with your doctor or pharmacist if you take any of the following: NMDA antagonists (worst risk—L-threonine may reduce their effect); antihypertensive drugs, ACE inhibitors, or ARBs (L-arginine and L-citrulline may dangerously lower blood pressure and raise potassium); blood thinners or antiplatelet drugs (L-arginine may increase bleeding risk); diabetes medications (L-arginine and L-cysteine may lower blood sugar too much); potassium-sparing diuretics (L-arginine may raise potassium to unsafe levels); sildenafil or other phosphodiesterase-5 inhibitors (L-arginine and L-citrulline may amplify blood pressure drop); levodopa (L-tyrosine may interfere with absorption); thyroid hormone (L-tyrosine may have additive effects); clozapine (L-glycine may reduce its effectiveness); anticonvulsants (L-glutamine may weaken them); serotonin drugs called 5-HT4 agonists (L-lysine may reduce their effects).

Check your own medication Run your meds through the checker above

The bottom line

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

This amino acid blend may appeal to people looking to support athletic recovery, cognitive function, or specific amino acid needs—but the evidence for most uses is not yet established. If you take blood pressure medications, diabetes drugs, blood thinners, psychiatric medications (especially NMDA antagonists or clozapine), levodopa, thyroid hormone, or anticonvulsants, check your exact medications with your doctor or pharmacist before starting, because several ingredients in this product interact with those drug classes.

For pregnancy or breastfeeding, talk with your healthcare provider first.

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

Assessment coverage: 14 of 20 active ingredients matched to our full ingredient reviews (monographs). Based on the product label dated Jan 24, 2024.

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 Free-Form Amino Acids, straight from the product label.

Brand Ecological Formulas
Barcode (UPC) 696859131332
Net contents 50 Gram(s)
Market status On market
Date entered into DSLD Jan 24, 2024
DSLD ID 304380
Product type Amino Acid/protein
Supplement form Powder
Dietary claims / uses Nutrient, All Other, Structure/Function
Intended target group(s) Adult (18 - 50 Years)
From the label
Everything in this section is reproduced from the manufacturer’s own product label — it’s the label speaking, not HelloPharmacist. We show it so you can see exactly what the maker states; we don’t verify or endorse those statements.

Supplement Facts

The label details for Free-Form Amino Acids by Ecological Formulas, sourced from the NIH Dietary Supplement Label Database.

Supplement Facts

Daily Value (DV) Target Group(s):
Adults and children 4 or more years of age
Minimum serving Sizes:
1 Gram(s)
Maximum serving Sizes:
1 Gram(s)
Servings per container
50
UPC/BARCODE
696859131332
IngredientAmount% DV
L-Leucine0 NP--
L-Arginine0 NP--
L-Isoleucine0 NP--
L-Methionine0 NP--
L-Citrulline0 NP--
L-Valine0 NP--
L-Proline0 NP--
L-Aspartic Acid0 NP--
L-Histidine0 NP--
L-Glutamic Acid0 NP--
L-Threonine0 NP--
L-Lysine0 NP--
L-Tyrosine0 NP--
L-Glutamine0 NP--
Amino Acids655 mg--
L-Glycine0 NP--
L-Alanine0 NP--
Essential Amino Acids345 mg--
L-Cysteine0 NP--
L-Cystine0 NP--
L-Serine0 NP--
L-Asparagine0 NP--

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.
FDA Statement of Identity

A Dietary Supplement

Dietary Supplement

Formula

Free from Amino Acids is a scientifically-designed supplement especially formulated for the allergic individual. Only the purest, reagent grade, individually resolved, crystalline amino acids are used. Twenty essential and non-essential amino acids are included.

Formulation

Phenylalanine, tryptophan, and hydroxyproline are excluded.

(Buccal Formula) without phenylalanine or tryptophan

Suggested/Recommended/Usage/Directions

Directions Dissolve one-quarter teaspoon (1000 mg) under the tongue for rapid absorption, or as directed by a physician. This formula may also be dissolved in water prior to ingestion for oral use.

FDA Disclaimer Statement

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

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

See for yourself

Free-Form Amino Acids by Ecological Formulas label

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

Free-Form Amino Acids 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 Free-Form Amino Acids by Ecological Formulas

These are the 20 active ingredients this product is made of. Select any to open its full monograph.

Serving size1 Gram(s) Dosage formPowder Servings per container50 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.

Amino Acids

655 mg per serving

Essential Amino Acids

345 mg per serving
Interaction report

Free-Form Amino Acids by Ecological Formulas Drug Interactions

Want to check YOUR meds against Free-Form Amino Acids?

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
481Drugs
3 Major 470 Moderate 8 Minor

Ingredients driving the most interactions

L-Arginine 403
L-Citrulline 178
L-Cysteine 86
L-Glutamine 50
L-Tyrosine 21

Individual Drug Interactions

The ingredients in Free-Form Amino Acids interact with 481 drugs. Click any drug to see the details.

8 of the 20 ingredients in Free-Form Amino Acids interact with drugs. Each result below shows which ingredient is responsible. L-Arginine L-Citrulline L-Cysteine L-Glutamine L-Tyrosine L-Threonine L-Glycine L-Lysine

Each ingredient & the kinds of drugs it affects

For each ingredient in Free-Form Amino Acids 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.

L-Arginine9 drug types · 403 drugs

Ace Inhibitors (Aceis)

Theoretically, concomitant use of L-arginine and ACE inhibitors may increase the risk for hypotension and hyperkalemia.
Combining L-arginine with some antihypertensive drugs, especially ACE inhibitors, seems to have additive vasodilating and blood pressure-lowering effects. Furthermore, ACE inhibitors can increase potassium levels. Use of L-arginine has been associated with hyperkalemia in some patients. Theoretically, concomitant use of ACE inhibitors with L-arginine may increases the risk of hyperkalemia.

Likelihood Probable Evidence D
Angiotensin Receptor Blockers (Arbs)

Theoretically, concomitant use of L-arginine and ARBs may increase the risk of hypotension and hyperkalemia.
L-arginine increases nitric oxide, which causes vasodilation. Combining L-arginine with ARBs seems to increase L-arginine-induced vasodilation. Furthermore, ARBs can increase potassium levels. Use of L-arginine has been associated with hyperkalemia in some patients. Theoretically, concomitant use of ARBs with L-arginine may increases the risk of hyperkalemia.

Likelihood Probable Evidence D
Anticoagulant/Antiplatelet Drugs

Theoretically, concomitant use of L-arginine with anticoagulant and antiplatelet drugs might have additive effects and increase the risk of bleeding.
Preliminary research suggests that L-arginine infusions reduce platelet aggregation in humans. The clinical significance of this effect is unclear.

Likelihood Possible Evidence D
Antidiabetes Drugs

Theoretically, concomitant use of L-arginine might have additive effects with antidiabetes drugs.
Preliminary clinical research shows that L-arginine decreases blood glucose levels in patients with type 2 diabetes.

Likelihood Possible Evidence D
Antihypertensive Drugs

Theoretically, concomitant use of L-arginine and antihypertensive drugs may increase the risk of hypotension.
L-arginine increases nitric oxide, which causes vasodilation. Clinical evidence shows that L-arginine can reduce blood pressure in some individuals with hypertension. Furthermore, combining L-arginine with some antihypertensive drugs seems to have additive vasodilating and blood pressure-lowering effects.

Likelihood Probable Evidence D
Isoproterenol (Isuprel)

Theoretically, concurrent use of isoproterenol and L-arginine might result in additive effects and hypotension.
Preliminary clinical evidence suggests that L-arginine enhances isoproterenol-induced vasodilation in patients with essential hypertension or a family history of essential hypertension.

Likelihood Probable Evidence D
Potassium-Sparing Diuretics

Theoretically concomitant use of potassium-sparing diuretics with L-arginine may increases the risk of hyperkalemia.
Potassium-sparing diuretics can increase potassium levels. Use of L-arginine has been associated with hyperkalemia in some patients.

Likelihood Possible Evidence D
Sildenafil (Viagra)

Theoretically, concurrent use of sildenafil and L-arginine might increase the risk for hypotension.
In vivo, concurrent use of L-arginine and sildenafil has resulted in increased vasodilation. Theoretically, concurrent use 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
Testosterone

Theoretically, concomitant use of L-arginine and testosterone might have additive effects.
In clinical research, L-arginine increases the level of testosterone in male patients with erectile dysfunction. The clinical significance of this finding is unclear.

Likelihood Possible Evidence D
L-Arginine full monograph & interactions

L-Citrulline2 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 full monograph & interactions

L-Cysteine1 drug type · 86 drugs

Antidiabetes Drugs

Theoretically, taking L-cysteine supplements with antidiabetes drugs might increase the risk of hypoglycemia.
Animal research suggests that L-cysteine can have hypoglycemic effects.

Likelihood Possible Evidence D
L-Cysteine full monograph & interactions

L-Glutamine1 drug type · 50 drugs

Anticonvulsants

Theoretically, glutamine might antagonize the effects of anticonvulsant medications.
Glutamine is metabolized to the excitatory neurotransmitter glutamate. Glutamate might have antagonistic effects with anticonvulsant drugs. However, this interaction has not yet been reported in humans.

Likelihood Possible Evidence D
L-Glutamine 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

L-Threonine1 drug type · 3 drugs

Nmda Antagonists

Theoretically, threonine might decrease the effects of NMDA antagonists.
Threonine increases central nervous system (CNS) glycine levels. Glycine seems to bind a site on NMDA receptors and enhance the activity of the receptors.

Likelihood Likely Evidence B
L-Threonine full monograph & interactions

L-Glycine1 drug type · 1 drug

Clozapine (Clozaril)

Theoretically, glycine might decrease the effectiveness of clozapine.
One small clinical study in patients with schizophrenia shows that adding glycine to clozapine therapy worsens symptoms of schizophrenia when compared with clozapine alone. The mechanism of this interaction is unclear.

Likelihood Probable Evidence B
L-Glycine full monograph & interactions

L-Lysine1 drug type · 1 drug

5-Ht4 Agonists

Theoretically, lysine may reduce the effects of 5-HT4 agonists.
Animal research suggests that L-lysine is a partial serotonin receptor 4 (5-HT4) antagonist and inhibits diarrhea induced by the 5-HT4 agonist, 5-hydroxytryptophane.

Likelihood Unlikely Evidence D
L-Lysine full monograph & interactions
The maker

Brand information

Manufacturer and brand details for Free-Form Amino Acids, from the product label.

Ecological Formulas

See all Ecological Formulas products
Name
Cardiovascular Research, LTD.
Street Address
1061-B Shary Circle
City
Concord
State
CA
ZipCode
94518
Pharmacist Counseling Corner

Free-Form Amino Acids by Ecological Formulas: Common Questions

Does Free-Form Amino Acids by Ecological Formulas interact with any medications?
Yes. Based on its ingredients, Free-Form Amino Acids has a known interaction with 481 medications, including 3 rated major. Use the checker to see how it interacts with a specific drug.
How can one product interact with so many drugs?
Free-Form Amino Acids contains 20 active ingredients, and an interaction can come from any of them. We check every ingredient, combine the results into one list per medication, and show which ingredient and mechanism is responsible.
Where does this information come from?
The product label data comes from the NIH Dietary Supplement Label Database (DSLD); the interaction data is built on the Natural Medicines database and reviewed by HelloPharmacist pharmacists.
Is this safe to take if I'm pregnant or breastfeeding?
It depends on which amino acid you're concerned about. L-methionine and L-glutamine are rated likely safe. L-arginine is possibly safe in pregnancy but has no data for breastfeeding. L-citrulline, L-threonine, L-lysine, L-tyrosine, L-glycine, and L-serine don't have enough safety data—the facts advise avoiding them in pregnancy and lactation unless your doctor specifically recommends them. L-aspartic acid is rated possibly unsafe in both. Talk with your doctor or pharmacist before taking this product while pregnant or nursing.
Can L-arginine really lower my blood pressure?
Yes. L-arginine increases a compound called nitric oxide, which relaxes blood vessels and can reduce blood pressure in some people with high blood pressure. That's why combining it with blood pressure medications could push your pressure too low. This is also why the product requires medical supervision—it's not just a benign supplement.
What are the most common side effects I might notice?
The most frequent mild side effects reported are gastrointestinal: abdominal pain, bloating, nausea, diarrhea, and heartburn. Headache, fatigue, and insomnia have also been reported with some ingredients. Most are dose-dependent and resolve if you lower the amount or stop taking it.
Does this help with muscle building or athletic performance?
L-citrulline is rated possibly effective for athletic performance, but for muscle strength, muscle size, and general athletic gain, the evidence we hold is insufficient—meaning it's not yet clear whether these amino acids deliver those benefits. Your doctor or a sports nutritionist can discuss whether amino acid supplementation makes sense for your training goals.
Why can't you check L-leucine, L-isoleucine, and some others for drug interactions?
We don't hold a data monograph for those ingredients, so we have no documented interaction information on file for them. That doesn't mean they don't interact with medications—it means we simply haven't reviewed the literature for them. If you take regular prescriptions, ask your pharmacist about those specific amino acids as well.
Can I use this with levodopa for Parkinson's disease?
L-tyrosine in this product competes with levodopa for absorption in your intestines, which may reduce how much levodopa your body gets. The recommendation is to take them at least 2 hours apart. Talk with your neurologist or pharmacist about the timing and whether this product is right for you.

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.

Free-Form Amino Acids label
Go deeper

The Full Monographs Behind Free-Form Amino Acids’s Ingredients

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

Herb & supplement monograph

L-arginine

Interacts with 403 drugs

L-arginine is an amino acid that the body uses to make nitric oxide, a substance that helps blood vessels relax and widen. It is popularly used for blood pressure, erectile dysfunction, and...

Read the full L-arginine monograph → 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

Proline

Proline is a non-essential amino acid that your body can make on its own and that you also get from protein-rich foods. It is a key building block of collagen, but strong human evidence that...

Read the full Proline monograph → Herb & supplement monograph

Aspartic Acid

Aspartic acid is a common amino acid your body makes on its own and gets from protein-rich foods, so a true deficiency is rare. D-aspartic acid is heavily marketed for boosting testosterone...

Read the full Aspartic Acid 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

Glutamine

Interacts with 50 drugs

Glutamine is the most abundant amino acid in the body and is usually made in your muscles. A prescription form is FDA-approved to help reduce sickle cell disease complications, but for most...

Read the full Glutamine monograph → Herb & supplement monograph

Glycine

Interacts with 1 drug

Glycine is a non-essential amino acid your body makes on its own and that also appears in protein-rich foods. It is most studied for improving sleep quality, where early research is promisin...

Read the full Glycine monograph → Herb & supplement monograph

Alpha-alanine

Alpha-alanine (usually called alanine) is a non-essential amino acid your body can make on its own and that you also get from protein foods. Most people do not need a supplement, and strong...

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

L-cysteine

Interacts with 86 drugs

L-cysteine is a sulfur-containing amino acid your body uses to make proteins and the antioxidant glutathione. Most people get enough from food, and supplements are usually well tolerated, bu...

Read the full L-cysteine monograph → Herb & supplement monograph

Serine

Serine is an amino acid your body can make on its own and also gets from protein-rich foods, so most people do not need a supplement. L-serine has been studied for certain neurological condi...

Read the full Serine monograph → Herb & supplement monograph

Methionine

Methionine is an essential amino acid that your body needs for protein building and many basic chemical reactions. Most people get enough from a normal diet, and supplements are generally no...

Read the full Methionine monograph → Herb & supplement monograph

Histidine

Histidine is an essential amino acid your body needs to build proteins and to make compounds like histamine and carnosine. Most people get enough from a normal diet, and good-quality researc...

Read the full Histidine monograph → Herb & supplement monograph

Threonine

Interacts with 3 drugs

Threonine is an essential amino acid your body needs but cannot make, so you must get it from food or supplements. Most people get plenty from a normal diet, and high-quality evidence for ta...

Read the full Threonine monograph → Herb & supplement monograph

Lysine

Interacts with 1 drug

Lysine is an essential amino acid your body cannot make on its own, so it must come from food or supplements. People most often take extra lysine to try to prevent or shorten cold sores, but...

Read the full Lysine monograph →
Sources

Sources & How We Checked

Free-Form Amino Acids'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 132 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.

L-arginine 66 references
  1. Sapienza MA, Kharitonov SA, Horvath I, et al. Effect of inhaled L-arginine on exhaled nitric oxide in normal and asthmatic subjects. Thorax 1998;53:172-5.
  2. Clarkson P, Adams MR, Powe AJ, et al. Oral L-arginine improves endothelium-dependent dilation in hypercholesterolemic young adults. J Clin Invest 1996;97:1989-94. PubMed
  3. Tenenbaum A, Fisman EZ, Motro M. L-arginine: Rediscovery in progress. Cardiology 1998;90:153-9.
  4. Brittenden J, Park KGM, Heys SD, et al. L-Arginine stimulates host defenses in patients with breast cancer. Surgery 1994;115:205-12.
  5. Korting GE, Smith SD, Wheeler MA, et al. A randomized double-blind trial of oral L-arginine for treatment of interstitial cystitis. J Urol 1999;161:558-65. DOI
  6. Rector TS, Bank AJ, Mullen KA, et al. Randomized, double-blind, placebo-controlled study of supplemental oral L-arginine in patients with heart failure. Circulation 1996;93:2135-41.
  7. Siani A, Pagano E, Iacone R, et al. Blood pressure and metabolic changes during dietary L-arginine supplementation in humans. Am J Hypertens 2000;13:547-51. PubMed
  8. Cheng JW, Balwin SN. L-arginine in the management of cardiovascular diseases. Ann Pharmacother 2001;35:755-64. PubMed
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L-citrulline 8 references
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Proline 4 references
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Aspartic Acid 1 reference
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Threonine 4 references
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Tyrosine 4 references
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Glutamine 11 references
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Glycine 5 references
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Alpha-alanine 2 references
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L-cysteine 2 references
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Serine 3 references
  1. Fridman V, Suriyanarayanan S, Novak P, et al. Randomized trial of l-serine in patients with hereditary sensory and autonomic neuropathy type 1. Neurology. 2019;92(4):e359-e370.
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See these in context on the Serine monograph →

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

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