Major interaction on record — check this product against your medications before combining. Based on 12 of 20 ingredients. Check your meds →
Dietary supplement

Amino 1900 Ingredients & Drug Interactions

by Universal

Amino 1900 label
See full label image
Tablet Or Pill Category: Other Combinations
Most serious interaction: Major
Clinical methodology reviewed by · Updated Sep 9, 2026 · Label data from the NIH DSLD
What is this page for?

First and foremost: checking Amino 1900 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

Amino 1900 is a dietary supplement by Universal with 20 active ingredients. Its ingredients are commonly taken for morning sickness in pregnancy, premenstrual syndrome (pms), preventing or treating b6 deficiency.Based on those ingredients, 595 medications have a known interaction with it, the most serious rated major. The ingredients most likely to interact are Tryptophan, Vitamin B6, Tyrosine. Use the checker below to test your specific medication, or read the full HelloPharmacist Interaction Report.

Jump to a section

Check Your Meds Against Amino 1900 by Universal

Ask about any prescription or over-the-counter medication and we check it for interactions with Amino 1900 by Universal — and tell you which ingredient is responsible.

Pharmacist-reviewed data Checks every ingredient Answer in seconds
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HelloPharmacist Scorecard of Amino 1900 by Universal

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 12, 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 19 of its 19 active ingredients.
  • No proprietary blends here — you can verify the dose of every single component.

Amino 1900 contains 19 amino acids — the building blocks your body uses to make and repair muscle, hormones, and other proteins. The active ingredients include vitamin B6 (a B vitamin that supports nerve and immune function), glycine, aspartic acid, tryptophan, methionine, arginine, leucine, serine, tyrosine, histidine, isoleucine, lysine, phenylalanine, threonine, valine, glutamic acid, alanine, proline, and cystine.

The product also contains inactive ingredients like dicalcium phosphate, stearic acid, magnesium stearate, lecithin, and a pharmaceutical glaze — these are fillers and binders that help form the tablet.

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

This product doesn't appear to be marketed for a specific use, so we graded its ingredients' overall clinical evidence instead.

Strong

Strong clinical evidence supports its ingredients for:

Why this rating?
  • We looked at the product name, claims, and label statements and couldn't find a stated purpose to grade.
  • Since the label doesn't commit to one use, we graded the ingredients' overall clinical evidence instead.
  • On file: Sideroblastic anemia — rated "Effective" (Vitamin B6) (Natural Medicines).
  • On file: Phenylketonuria (PKU) — rated "Effective" (Tyrosine) (Natural Medicines).
  • On file: Vitamin B6 deficiency — rated "Effective" (Vitamin B6) (Natural Medicines).
  • On file: Pyridoxine-dependent epilepsy — rated "Effective" (Vitamin B6) (Natural Medicines).
  • On file: Hyperhomocysteinemia — rated "Likely Effective" (Vitamin B6) (Natural Medicines).

Vitamin B6 in this product is effective for sideroblastic anemia and B6 deficiency, and likely effective for lowering homocysteine. It is possibly effective for pregnancy-related nausea.

For the amino acids, the evidence is mixed. Tyrosine is effective for phenylketonuria (PKU) and possibly effective for cognitive function and memory.

Phenylalanine is possibly effective for vitiligo. Lysine is possibly effective for cold sores.

Glycine is possibly effective for schizophrenia. Serine is possibly effective for schizophrenia.

For the others — aspartic acid, methionine, arginine, leucine, histidine, isoleucine, threonine, valine, glutamic acid, alanine, proline, and cystine — the evidence is insufficient to rate them, meaning we don't have enough data on file to say whether they work for any particular condition.

The evidence, ingredient by ingredient Vitamin B6 Glycine Aspartic Acid L-tryptophan Methionine Serine Tyrosine Histidine

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 12 matched ingredients.
  • Pregnancy & breastfeeding safety ratings cover 12 of 12.
  • General safety write-ups exist for 12 of 12.
  • Remember: this measures how much safety information exists. Thin data is not the same as being safe.

Vitamin B6 is generally well tolerated at doses under 100 mg daily but can cause nerve damage (sensory neuropathy) at high doses or with long-term use — avoid doses over 1,000 mg daily. L-tryptophan is generally well tolerated but has a history of a contaminated-product safety scare in the 1980s and can cause drowsiness and gastrointestinal upset.

Tyrosine, lysine, histidine, and proline appear generally well tolerated in typical doses, though long-term safety data are limited for most. Glycine is generally well tolerated but long-term safety is not well studied.

Serine can cause gastrointestinal distress and, at very high doses, seizures. Methionine can cause dizziness, drowsiness, and low blood pressure, and high doses may raise homocysteine levels.

Phenylalanine can cause anxiety, insomnia, and constipation. Aspartic acid has limited supplement safety data.

Threonine may cause headache and minor gastrointestinal upset. We hold no adverse-effect data for arginine, leucine, isoleucine, valine, glutamic acid, alanine, or cystine.

Side effects, ingredient by ingredient Vitamin B6 Glycine Aspartic Acid L-tryptophan Methionine Serine Tyrosine Histidine

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?
  • 7 of the 12 matched ingredients can interact with medications — Lysine, L-tryptophan, Phenylalanine, Vitamin B6, Tyrosine, among others.
  • The most serious interaction on file is rated Major.
  • Some involve high-stakes drug classes: Parkinson's medications.
  • For scale: 595 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 Amino 1900, double-check with your pharmacist or doctor if you take any of these: levodopa (Parkinson disease) — phenylalanine and tyrosine both reduce its effectiveness; CNS depressants like sedatives or opioids — L-tryptophan can add to drowsiness; serotonergic antidepressants or migraine drugs — L-tryptophan raises serotonin-syndrome risk; anti-seizure drugs (phenobarbital, phenytoin) — vitamin B6 may reduce their levels; antihypertensive blood-pressure drugs — vitamin B6 may lower pressure further; clozapine (schizophrenia) — glycine may worsen symptoms; NMDA antagonists (ketamine, memantine) — threonine may reduce effectiveness; thyroid hormone — tyrosine may amplify effects; or baclofen (muscle relaxer) or MAOIs (older antidepressants) — phenylalanine interferes with both.

Check your own medication Run your meds through the checker above

The bottom line

Scorecard at a glanceFully disclosed formula with strong clinical evidence behind its ingredients' uses. Major medication interactions have been identified, and safety information is well characterized.

Amino 1900 is an amino-acid blend with some solid evidence behind vitamin B6 and a few of the amino acids. But it interacts with several important medication classes — especially levodopa, CNS depressants, serotonergic drugs, and anti-seizure medications.

If you take any prescription medication, run it through our interaction checker below before you start. If you're pregnant, nursing, or considering high-dose amino supplementation, check with your pharmacist or doctor first.

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

Assessment coverage: 12 of 19 active ingredients matched to our full ingredient reviews (monographs). Based on the product label dated Aug 24, 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 Amino 1900, straight from the product label.

Brand Universal
Barcode (UPC) 039442045423
Net contents 110 Tablet(s)
Market status On market
Date entered into DSLD Aug 24, 2016
DSLD ID 64049
Product type Other Combinations
Supplement form Tablet Or Pill
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 Amino 1900 by Universal, 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:
4 Tablet(s)
Maximum serving Sizes:
4 Tablet(s)
Servings per container
27
UPC/BARCODE
039442045423
IngredientAmount% DV
Calories24 Calorie(s)--
Protein6 Gram(s)12%
Vitamin B620 mg1000%
Glycine105 mg--
Aspartic Acid630 mg--
Tryptophan100 mg--
Methionine125 mg--
Arginine140 mg--
Leucine645 mg--
Serine275 mg--
Tyrosine180 mg--
Histidine115 mg--
Isoleucine365 mg--
Lysine535 mg--
Phenylalanine200 mg--
Threonine380 mg--
Valine340 mg--
Glutamic Acid1000 mg--
Alanine285 mg--
Proline325 mg--
Cystine145 mg--

Other ingredients: Extra-Strength Amino Blend, Dicalcium Phosphate, Water, Stearic Acid, Magnesium Stearate, Lecithin, Pyridoxine Hydrochloride, Pharmaceutical Glaze

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.
Precautions

Warning: This product is not for use by any individual under the age of 18.

Please consult with a physician before using this product.

Do not take this product if you have or are at risk for any medical condition or disease including but not limited to diabetes, asthma, depression, recurrent headaches, glaucoma, difficulty urinating, prostate enlargement, seizure disorder, high blood pressure, high cholesterol, arthritis, heart disease, stroke, are pregnant, or are suffering from any inflammatory diseases. Be sure to talk to your physician before using this product if you are using any prescription drug, over-the-counter medication, or supplements. Not for use by children, patients, pregnant or nursing women.

Not for use by children, patients, pregnant or nursing women.

Immediately discontinue use and consult your physician if dizziness, sleeplessness, tremors, nervousness, agitation, headache, heart palpitations, or any side effects occur. Discontinue use two weeks prior to surgery. The use of this product may be banned by some athletic associations. Athletes should consult with their sanctioning authority before use. California Residents Proposition 65 Warning: This product contains a substance known to the State of California to cause birth defects or other reproductive harm.

Exercise good judgment and keep this out of reach of children.

Do not exceed recommended dose.

Made in a GMP facility on equipment that processes milk, soy, egg, peanuts, tree nuts, fish, shellfish, and wheat.

Storage

Store this product in a cool, dry place, away from heat, moisture and sunlight.

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.

General Statements

Plant #3001104580

EAC

Made proudly in the U.S.A.

WHO WE ARE Universal Nutrition has been providing cutting edge and staple nutritional supplements to bodybuilders and hard training athletes the world over since 1977. As time passes, certain ideals never go out of style. Honesty. Integrity. Respect. These are the values we uphold and are the bedrock upon which we built our business.

HOW WE BACK IT UP What is on the label is in the bottle and what is in the bottle will help you reach your goals. We believe it and proudly stand behind every product we manufacture. Our word is our bond.

Brand IP Statement(s)

2015UniversalNutrition

WHAT IT IS Amino 1900 contains the highest potency of superior peptide bonded amino acids and is scientifically balanced to help you achieve optimum muscle growth, recover faster and enhance performance.

FDA Statement of Identity

Dietary Supplement

Formula

Sustained release Peptide Bonded Amino Acids Contains all nine EAA's & all three BCAA's With added B6 for absorption

General

C2515-G-33163

Suggested/Recommended/Usage/Directions

Dosage: As a dietary supplement, take 3-5 tablets on an empty stomach three times daily before meals and after training (10-15 tablets per day), or as directed by a Healthcare professional.

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

See for yourself

Amino 1900 by Universal label

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

Amino 1900 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 Amino 1900 by Universal

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

Serving size4 Tablet(s) Dosage formTablet Or Pill Servings per container27 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.

Protein

6 Gram(s) per serving

Vitamin B6

Interacts with
210 drugs
20 mg per serving

Vitamin B6 (pyridoxine) is an essential water-soluble vitamin that your body needs for metabolism, brain function, and making red blood cells. It is b...

Vitamin B6 monograph & interactions

Glycine

Interacts with
1 drug
105 mg per serving

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 q...

Glycine monograph & interactions

Aspartic Acid

No known
interactions
630 mg per serving

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 hea...

Aspartic Acid monograph & interactions

Tryptophan

Interacts with
394 drugs
100 mg per serving

L-tryptophan is an essential amino acid the body uses to make serotonin and melatonin, and people take it to support sleep and mood. The evidence for...

Tryptophan monograph & interactions

Methionine

No known
interactions
125 mg per serving

Methionine is an essential amino acid that your body needs for protein building and many basic chemical reactions. Most people get enough from a norma...

Methionine monograph & interactions

Arginine

140 mg per serving

Leucine

645 mg per serving

Serine

No known
interactions
275 mg per serving

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 bee...

Serine monograph & interactions

Tyrosine

Interacts with
21 drugs
180 mg per serving

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

Tyrosine monograph & interactions

Histidine

No known
interactions
115 mg per serving

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...

Histidine monograph & interactions

Isoleucine

365 mg per serving

Lysine

Interacts with
1 drug
535 mg per serving

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 t...

Lysine monograph & interactions

Phenylalanine

Interacts with
16 drugs
200 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...

Phenylalanine monograph & interactions

Threonine

Interacts with
3 drugs
380 mg per serving

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 norma...

Threonine monograph & interactions

Valine

340 mg per serving

Glutamic Acid

1000 mg per serving

Alanine

285 mg per serving

Proline

No known
interactions
325 mg per serving

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...

Proline monograph & interactions

Cystine

145 mg per serving

Other (inactive) ingredients: Extra-Strength Amino Blend, Dicalcium Phosphate, Water, Stearic Acid, Magnesium Stearate, Lecithin, Pyridoxine Hydrochloride, Pharmaceutical Glaze. These complete the product’s ingredient list but are not active constituents.

Interaction report

Amino 1900 by Universal Drug Interactions

Want to check YOUR meds against Amino 1900?

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
595Drugs
256 Major 339 Moderate

Ingredients driving the most interactions

Tryptophan 394
Vitamin B6 210
Tyrosine 21
Phenylalanine 16
Threonine 3

Individual Drug Interactions

The ingredients in Amino 1900 interact with 595 drugs. Click any drug to see the details.

7 of the 20 ingredients in Amino 1900 interact with drugs. Each result below shows which ingredient is responsible. Tryptophan Vitamin B6 Tyrosine Phenylalanine Threonine Glycine Lysine

Each ingredient & the kinds of drugs it affects

For each ingredient in Amino 1900 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.

Tryptophan2 drug types · 394 drugs

Cns Depressants

Theoretically, concomitant use of L-tryptophan with CNS depressants might cause additive sedative effects.
Clinical research shows that L-tryptophan can cause fatigue and drowsiness.

Likelihood Probable Evidence B
Serotonergic Drugs

Theoretically, combining L-tryptophan with serotonergic drugs might cause additive serotonergic effects.
L-tryptophan is a precursor to serotonin. Theoretically, combining serotonergic drugs with L-tryptophan might increase the risk of serotonergic side effects, including serotonin syndrome and cerebral vasoconstrictive disorders.

Likelihood Possible Evidence D
Tryptophan full monograph & interactions

Vitamin B65 drug types · 210 drugs

Amiodarone (Cordarone)

Theoretically, vitamin B6 might increase the photosensitivity caused by amiodarone.
Despite initial case reports suggesting that pyridoxine may have a protective effect against amiodarone-induced photosensitivity, preliminary clinical research suggests that pyridoxine may actually exacerbate this adverse effect.

Likelihood Possible Evidence B
Antihypertensive Drugs

Theoretically, vitamin B6 may have additive effects when used with antihypertensive drugs.
Research in hypertensive rats shows that vitamin B6 can decrease systolic blood pressure. Similarly, clinical research in patients with hypertension shows that taking high doses of vitamin B6 may reduce systolic and diastolic blood pressure, possibly by reducing plasma levels of epinephrine and norepinephrine.

Likelihood Possible Evidence B
Phenobarbital (Luminal)

High doses of vitamin B6 may reduce the levels and clinical effects of phenobarbital.
Preliminary clinical evidence suggests that vitamin B6 200 mg daily can reduce plasma levels of phenobarbital, possibly by increasing metabolism. It is not known whether lower doses have any effect. Advise people taking phenobarbital to avoid high doses of vitamin B6.

Likelihood Possible Evidence D
Phenytoin (Dilantin)

High doses of vitamin B6 may reduce the levels and clinical effects of phenytoin.
Preliminary clinical evidence suggests that vitamin B6 200 mg daily can reduce plasma levels of phenytoin, possibly by increasing metabolism. It is not known whether lower doses have any effect. Advise people taking phenytoin to avoid high doses of vitamin B6.

Likelihood Possible Evidence D
Levodopa

Vitamin B6 may increase the metabolism of levodopa when taken alone, but not when taken in conjunction with carbidopa.
Vitamin B6 (pyridoxine) enhances the metabolism of levodopa, reducing its clinical effects. However, this interaction does not occur when carbidopa is used concurrently with levodopa (Sinemet). Therefore, it is not likely to be a problem in most people.

Likelihood Unlikely Evidence D
Vitamin B6 full monograph & interactions

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
Tyrosine full monograph & interactions

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
Phenylalanine full monograph & interactions

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
Threonine full monograph & interactions

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
Glycine full monograph & interactions

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
Lysine full monograph & interactions
The maker

Brand information

Manufacturer and brand details for Amino 1900, from the product label.

Universal

See all Universal products
Name
Universal Nutrition
City
New Brunswick
State
New Jersey
ZipCode
08901
Phone Number
800-872-0101
Web Address
www.UniversalUSA.com
Pharmacist Counseling Corner

Amino 1900 by Universal: Common Questions

Does Amino 1900 by Universal interact with any medications?
Yes. Based on its ingredients, Amino 1900 has a known interaction with 595 medications, including 256 rated major. Use the checker to see how it interacts with a specific drug.
How can one product interact with so many drugs?
Amino 1900 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.
Does this amino-acid blend actually help build muscle or improve athletic performance?
The data we hold say that tyrosine is possibly ineffective for athletic performance and phenylalanine is possibly ineffective for it as well. For the other amino acids in this blend — aspartic acid, leucine, valine, and others — the evidence is insufficient to rate. Talk to your trainer or doctor about whether amino supplements fit your routine.
Can I take Amino 1900 if I'm pregnant?
It depends on the ingredient. Phenylalanine is unsafe in pregnancy, so you should avoid this product if you're pregnant. Vitamin B6, L-tryptophan, and aspartic acid are possibly unsafe. Several others have insufficient data. The safest move is to talk to your doctor or pharmacist before taking any supplement during pregnancy.
What's the most serious drug interaction I should worry about?
If you take levodopa for Parkinson disease, phenylalanine in this product can significantly reduce how well it works. And if you take CNS depressants like sedatives or sleep aids, L-tryptophan can add to drowsiness in a major way. Both are reasons to check with your pharmacist before starting.
Is vitamin B6 in this supplement dangerous?
Vitamin B6 at normal supplemental doses (under 100 mg daily) is well tolerated. But at high doses or with long-term use, it can cause nerve damage. The product facts advise avoiding high doses, so stick to the label directions and don't exceed them without medical guidance.
Why can't you check some ingredients for interactions?
Arginine, leucine, isoleucine, valine, glutamic acid, alanine, and cystine don't have interaction data on file in our monographs. That doesn't mean they're safe or unsafe with your medications — it just means we haven't checked them. If you take prescription drugs, ask your pharmacist about these ingredients too.
What happens if I take L-tryptophan with an antidepressant?
L-tryptophan boosts serotonin, and many antidepressants do the same. Together, they could theoretically raise the risk of serotonin syndrome — a rare but serious condition with agitation, confusion, rapid heartbeat, and muscle rigidity. Don't combine them without your doctor's explicit OK.

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

Not sure if Amino 1900 is safe with your meds?

Our pharmacists answer your medication & supplement questions — free.

Ask a pharmacist

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.

Amino 1900 label
Go deeper

The Full Monographs Behind Amino 1900’s Ingredients

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

Herb & supplement monograph

Vitamin B6

Interacts with 210 drugs

Vitamin B6 (pyridoxine) is an essential water-soluble vitamin that your body needs for metabolism, brain function, and making red blood cells. It is best known for helping with pregnancy-rel...

Read the full Vitamin B6 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

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

L-tryptophan

Interacts with 394 drugs

L-tryptophan is an essential amino acid the body uses to make serotonin and melatonin, and people take it to support sleep and mood. The evidence for supplement use is limited and mixed, and...

Read the full L-tryptophan 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

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

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

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

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 → 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

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

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...

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Sources

Sources & How We Checked

Amino 1900'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 116 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.

Vitamin B6 32 references
  1. Hansten PD, Horn JR. Drug Interactions Analysis and Management. Vancouver, WA: Applied Therapeutics Inc., 1997 and updates.
  2. Yates AA, Schlicker SA, Suitor CW. Dietary reference intakes: The new basis for recommendations for calcium and related nutrients, B vitamins, and choline. J Am Diet Assoc 1998;98:699-706. PubMed
  3. Geerling BJ, Dagnelie PC, Badart-Smook A, et al. Diet as a risk factor for the development of ulcerative colitis. Am J Gastroenterol 2000;95:1008-13. PubMed
  4. South M. Neonatal seizures after pyridoxine use -- reply. Lancet 1999;354:2083. PubMed
  5. Food and Nutrition Board, Institute of Medicine. Dietary Reference Intakes for Thiamin, Riboflavin, Niacin, Vitamin B6, Folate, Vitamin B12, Pantothenic Acid, Biotin, and Choline (2000). Washington, DC: National Academy Press, 2000. Available at: http://b
  6. Baxter P, Aicardi J. Neonatal seizures after pyridoxine use. Lancet 1999;354:2082-3. PubMed
  7. Bendich A, Cohen M. Vitamin B6 safety issues. Ann N Y Acad Sci 1990;585:321-30.
  8. Schaumburg H, Kaplan J, Windebank A. Sensory neuropathy from pyridoxine abuse. A new megavitamin syndrome. N Engl J Med 1983;309:445-8. PubMed
  9. Gordon N. Pyridoxine dependency: an update. Dev Med Child Neurol 1997;39:63-5. PubMed
  10. Lewis PJ. Pain in the hand and wrist. Pyridoxine supplements may help patients with carpal tunnel syndrome. BMJ 1995;310:1534. PubMed
  11. Kaufman G. Pyridoxine against amiodarone-induced photosensitivity (letter). Lancet 1984;1:51-2. PubMed
  12. Mulrow JP, Mulrow CD, McKenna WJ. Pyridoxine and amiodarone-induced photosensitivity. Ann Intern Med 1985;103:68-9. PubMed
  13. Kawada A, Kashima A, Shiraishi H, et al. Pyridoxine-induced photosensitivity and hypophosphatasia. Dermatology 2000;201:356-60.. PubMed
  14. Vasile A, Goldberg R, Kornberg B. Pyridoxine toxicity: report of a case. J Am Osteopath Assoc 1984;83:790-1. DOI
  15. Hansson O, Sillanpaa M. Pyridoxine and serum concentration of phenytoin and phenobarbitone. Lancet 1976;1:256. DOI
  16. Jansen T, Romiti R, Kreuter A, Altmeyer P. Rosacea fulminans triggered by high-dose vitamins B6 and B12. J Eur Acad Dermatol Venereol 2001;15:484-5..
  17. Chittumma P, Kaewkiattikun K, Wiriyasiriwach B. Comparison of the effectiveness of ginger and vitamin B6 for treatment of nausea and vomiting in early pregnancy: a randomized double-blind controlled trial. J Med Assoc Thai 2007;90:15-20.
  18. Hatzitolios, A., Iliadis, F., Katsiki, N., and Baltatzi, M. Is the anti-hypertensive effect of dietary supplements via aldehydes reduction evidence based? A systematic review. Clin Exp.Hypertens. 2008;30(7):628-639. PubMed
  19. Vasdev, S., Ford, C. A., Parai, S., Longerich, L., and Gadag, V. Dietary vitamin B6 supplementation attenuates hypertension in spontaneously hypertensive rats. Mol.Cell Biochem. 1999;200(1-2):155-162.
  20. de, Vogel S., Dindore, V., van, Engeland M., Goldbohm, R. A., van den Brandt, P. A., and Weijenberg, M. P. Dietary folate, methionine, riboflavin, and vitamin B-6 and risk of sporadic colorectal cancer. J Nutr 2008;138(12):2372-2378. PubMed
  21. Hagen, I., Nesheim, B. I., and Tuntland, T. No effect of vitamin B-6 against premenstrual tension. A controlled clinical study. Acta Obstet.Gynecol.Scand. 1985;64(8):667-670. PubMed
  22. Aybak, M., Sermet, A., Ayyildiz, M. O., and Karakilcik, A. Z. Effect of oral pyridoxine hydrochloride supplementation on arterial blood pressure in patients with essential hypertension. Arzneimittelforschung. 1995;45(12):1271-1273.
  23. Lal, K. J., Dakshinamurti, K., and Thliveris, J. The effect of vitamin B6 on the systolic blood pressure of rats in various animal models of hypertension. J Hypertens. 1996;14(3):355-363. PubMed
  24. Lauritzen CH, Reuter HD, Repges R, Bohnert K, and Schmidt U. Treatment of premenstrual tension syndrome with Vitex agnus castus. Controlled, double-blind study versus pyridoxine. Phytomed 1997;4(3):183-189. PubMed
  25. Fonseca VA, Lavery LA, Thethi TK, et al. Metanx in type 2 diabetes with peripheral neuropathy: A randomized trial. Am J Med 2013;126(2):141-9. PubMed
  26. Hankey GJ, Eikelboom JW, Yi Q, et al. Treatment with B vitamins and incidence of cancer in patients with previous stroke or transient ischemic attack: Results of a randomized placebo-controlled trial. Stroke 2012;43(6):1572-7. PubMed
  27. Hoyer-Kuhn H, Kohbrok S, Volland R, Franklin J, Hero B, Beck BB, Hoppe B. Vitamin B6 in primary hyperoxaluria I: first prospective trial after 40 years of practice. Clin J Am Soc Nephrol. 2014 Mar;9(3):468-77. PubMed
  28. Mahmoud A, Tabassum S, Al Enazi S, et al. Amelioration of levetiracetam-induced behavioral side effects by pyridoxine. A randomized double blind controlled study. Pediatr Neurol 2021;119:15-21. PubMed
  29. Gupta M, Gallante B, Bamberger JN, et al. Prospective randomized evaluation of idiopathic hyperoxaluria treatments. J Endourol 2021;35(12):1844-1851. PubMed
  30. Li H, Chen M, Liang S, et al. Excessive vitamin B6 during treatment is related to poor prognosis of patients with nasopharyngeal carcinoma: A U-shaped distribution suggests low dose supplement. Clin Nutr 2021;40(4):2293-2300. PubMed
  31. Tanigawa J, Nabatame S, Tominaga K, et al. High-dose pyridoxine treatment for inherited glycosylphosphatidylinositol deficiency. Brain Dev 2021;43(6):680-687. PubMed
  32. Committee on Practice Bulletins-Obstetrics. ACOG Practice Bulletin No. 189: Nausea And Vomiting Of Pregnancy. Obstet Gynecol. 2018;131(1):e15-e30. PubMed

See these in context on the Vitamin B6 monograph →

Glycine 5 references
  1. Heresco-Levy U, Javitt DC, Ermilov M, et al. Efficacy of high-dose glycine in the treatment of enduring negative symptoms of schizophrenia. Arch Gen Psychiatry 1999;56:29-36.. PubMed
  2. Potkin SG, Jin Y, Bunney BG, Costa J, Gulasekaram B. Effect of clozapine and adjunctive high-dose glycine in treatment-resistant schizophrenia. Am J Psychiatry 1999;156:145-7.. PubMed
  3. Gusev EI, Skvortsova VI, Dambinova SA, et al. Neuroprotective effects of glycine for therapy of acute ischaemic stroke. Cerebrovasc Dis 2000;10:49-60. PubMed
  4. Inagawa K, Kawai N, Ono K, Sukegawa E, Tsubuku S, Takahashi M. Assessment of acute adverse effects of glycine ingestion at a high dose in human volunteers. Seikatsu Eisei. 2006; 50:27-32.
  5. Woods SW, Walsh BC, Hawkins KA, Miller TJ, Saksa JR, D'Souza DC, Pearlson GD, Javitt DC, McGlashan TH, Krystal JH. Glycine treatment of the risk syndrome for psychosis: report of two pilot studies. Eur Neuropsychopharmacol. 2013 Aug;23(8):931-40. PubMed

See these in context on the Glycine monograph →

Aspartic Acid 1 reference
  1. Food and Nutrition Board, Institute of Medicine. Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids. Washington, DC: The National Academies Press, 2005. Available at: https://doi.org/10.17226 DOI

See these in context on the Aspartic Acid monograph →

L-tryptophan 18 references
  1. Messiha FS. Fluoxetine: adverse effects and drug-drug interactions. J Toxicol Clin Toxicol 1993;31:603-30. PubMed
  2. Devoe LD, Castillo RA, Searle NS. Maternal dietary substrates and human fetal biophysical activity. The effects of tryptophan and glucose on fetal breathing movements. Am J Obstet Gynecol 1986;155:135-9. DOI
  3. Lieberman HR, Corkin S, Spring BJ. The effects of dietary neurotransmitter precursors on human behavior. Am J Clin Nutr 1985;42:366-70. PubMed
  4. U. S. Food and Drug Administration, Center for Food Safety and Applied Nutrition, Office of Nutritional Products, Labeling, and Dietary Supplements. Information Paper on L-Tryptophan and 5-hydroxy-L-tryptophan, February 2001.
  5. Sullivan EA, Kamb ML, Jones JL, et al. The natural history of eosinophilia-myalgia syndrome in a tryptophan-exposed cohort in South Carolina. Arch Intern Med 1996;156:973-9. DOI
  6. Philen RM, Hill RH, Flanders WD, et al. Tryptophan contaminants associated with eosinophilia-myalgia syndrome. Am J Epidemiol 1993;138:154-9. PubMed
  7. Bohme A, Wolter M, Hoelzer D. L-tryptophan-related eosinophilia-myalgia syndrome possibly associated with a chronic B-lymphocytic leukemia. Ann Hematol 1998;77:235-8. PubMed
  8. Singhal AB, Caviness VS, Begleiter AF, et al. Cerebral vasoconstriction and stroke after use of serotonergic drugs. Neurology 2002;58:130-3. PubMed
  9. Priori R, Conti F, Luan FL, et al. Chronic fatigue: a peculiar evolution of eosinophilia myalgia syndrome following treatment with L-tryptophan in four Italian adolescents. Eur J Pediatr 1994;153:344-6..
  10. Klein R, Berg PA. A comparative study on antibodies to nucleoli and 5-hydroxytryptamine in patients with fibromyalgia syndrome and tryptophan-induced eosinophilia-myalgia syndrome. Clin Investig 1994;72:541-9.. PubMed
  11. Simat TJ, Kleeberg KK, Muller B, Sierts A. Synthesis, formation, and occurrence of contaminants in biotechnologically manufactured L-tryptophan. Adv Exp Med Biol 1999;467:469-80.. PubMed
  12. Shaw K, Turner J, Del Mar C. Tryptophan and 5-hydroxytryptophan for depression. Cochrane Database Syst Rev 2002;(1):CD003198. PubMed
  13. Kilbourne EM, Philen RM, Kamb ML, Falk H. Tryptophan produced by Showa Denko and epidemic eosinophilia-myalgia syndrome. J Rheumatol Suppl 1996;46:81-8.
  14. Horwitz RI, Daniels SR. Bias or biology: evaluating the epidemiologic studies of L-tryptophan and the eosinophilia-myalgia syndrome. J Rheumatol Suppl 1996;46:60-72.
  15. Shapiro S. Epidemiologic studies of the association of L-tryptophan with the eosinophilia-myalgia syndrome: a critique. J Rheumatol Suppl 1996;46:44-58.
  16. Mayeno AN, Gleich GJ. The eosinophilia-myalgia syndrome: lessons from Germany. Mayo Clin Proc 1994;69:702-4. PubMed
  17. Carr L, Ruther E, Berg PA, Lehnert H. Eosinophilia-myalgia syndrome in Germany: an epidemiologic review. Mayo Clin Proc 1994;69:620-5. PubMed
  18. Ullrich SS, Fitzgerald PCE, Giesbertz P, Steinert RE, Horowitz M, Feinle-Bisset C. Effects of intragastric administration of tryptophan on the blood glucose response to a nutrient drink and energy intake, in lean and obese men. Nutrients 2018;10(4). pii: PubMed

See these in context on the L-tryptophan monograph →

Methionine 12 references
  1. La Vecchia C, Negri E, Franceschi S, Decarli A. Case-control study on influence of methionine, nitrite, and salt on gastric carcinogenesis in northern Italy. Nutr Cancer 1997;27:65-8. PubMed
  2. Btaiche IF, Khalidi N. Parenteral nutrition-associated liver complications in children. Pharmacotherapy 2002;22:188-211.. PubMed
  3. Cottington EM, LaMantia C, Stabler SP, et al. Adverse event associated with methionine loading test: a case report. Arterioscler Thromb Vasc Biol 2002;22:1046-50.. PubMed
  4. Anon. Should methionine be added to paracetamol formulations? Drug Ther Perspect 1997;10:11-3. DOI
  5. Smulders, Y. M., Rakic, M., Slaats, E. H., Treskes, M., Sijbrands, E. J., Odekerken, D. A., Stehouwer, C. D., and Silberbusch, J. Fasting and post-methionine homocysteine levels in NIDDM. Determinants and correlations with retinopathy, albuminuria, and c
  6. McAuley, D. F., Hanratty, C. G., McGurk, C., Nugent, A. G., and Johnston, G. D. Effect of methionine supplementation on endothelial function, plasma homocysteine, and lipid peroxidation. J.Toxicol.Clin.Toxicol. 1999;37(4):435-440. PubMed
  7. Hanratty, C. G., McGrath, L. T., McAuley, D. F., Young, I. S., and Johnston, G. D. The effects of oral methionine and homocysteine on endothelial function. Heart 2001;85(3):326-330. PubMed
  8. Ward, M., McNulty, H., McPartlin, J., Strain, J. J., Weir, D. G., and Scott, J. M. Effect of supplemental methionine on plasma homocysteine concentrations in healthy men: a preliminary study. Int.J.Vitam.Nutr.Res. 2001;71(1):82-86. PubMed
  9. Yaghmai, R., Kashani, A. H., Geraghty, M. T., Okoh, J., Pomper, M., Tangerman, A., Wagner, C., Stabler, S. P., Allen, R. H., Mudd, S. H., and Braverman, N. Progressive cerebral edema associated with high methionine levels and betaine therapy in a patient
  10. Talukdar R, Murthy HV, Reddy DN. Role of methionine containing antioxidant combination in the management of pain in chronic pancreatitis: a systematic review and meta-analysis. Pancreatology 2015;15(2):136-44. PubMed
  11. Food and Nutrition Board, Institute of Medicine. Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids. Washington, DC: The National Academies Press, 2005. Available at: https://doi.org/10.17226 DOI
  12. Khairan P, Sobue T, Eshak ES, et al. Association of B Vitamins and Methionine Intake with the Risk of Gastric Cancer: The Japan Public Health Center-based Prospective Study. Cancer Prev Res (Phila) 2022;15(2):101-110. PubMed

See these in context on the Methionine monograph →

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.
  2. Kantrowitz JT, Malhotra AK, Cornblatt B, et al. High dose D-serine in the treatment of schizophrenia. Schizophr Res. 2010 Aug;121(1-3):125-30. PubMed
  3. Levine TD, Miller RG, Bradley WG, et al. Phase I clinical trial of safety of L-serine for ALS patients. Amyotroph Lateral Scler Frontotemporal Degener. 2017;18(1-2):107-111. PubMed

See these in context on the Serine monograph →

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 →

Histidine 3 references
  1. Histidine — MedlinePlus (U.S. National Library of Medicine) Source
  2. Amino Acids — MedlinePlus (U.S. National Library of Medicine) Source
  3. Dietary Supplements: What You Need to Know — NIH Office of Dietary Supplements Source

See these in context on the Histidine monograph →

Lysine 7 references
  1. Thein DJ, Hurt WC. Lysine as a prophylactic agent in the treatment of recurrent herpes simplex labialis. Oral Surg Oral Med Oral Pathol 1984;58:659-66. PubMed
  2. McCune MA, Perry HO, Muller SA, O'Fallon WM. Treatment of recurrent herpes simplex infections with L-lysine monohydrochloride. Cutis 1984;34:366-73.
  3. DiGiovanna JJ, Blank H. Failure of lysine in frequently recurrent herpes simplex infection. Treatment and prophylaxis. Arch Dermatol 1984;120:48-51. DOI
  4. Milman N, Scheibel J, Jessen O. Lysine prophylaxis in recurrent herpes simplex labialis: a double-blind, controlled crossover study. Acta Derm Venereol 1980;60:85-7.
  5. Griffith RS, Walsh DE, Myrmel KH, et al. Success of L-lysine therapy in frequently recurrent herpes simplex infection. Treatment and prophylaxis. Dermatologica 1987;175:183-90. DOI
  6. Lo JC, Chertow GM, Rennke H, Seifter JL. Fanconi's syndrome and tubulointerstitial nephritis in association with L-lysine ingestion. Am J Kidney Dis 1996;28:614-7. PubMed
  7. Smriga M, Torii K. L-Lysine acts like a partial serotonin receptor 4 antagonist and inhibits serotonin-mediated intestinal pathologies and anxiety in rats. Proc Natl Acad Sci U S A. 2003 Dec 23;100(26):15370-5.

See these in context on the Lysine monograph →

Phenylalanine 23 references
  1. Rouse B, Azen C, Koch R, et al. Maternal phenylketonuria collaborative Study (MPKUCS) offspring: facial anomalies, malformations, and early neurological sequelae. Am J Med Genet 1997;69:89-95. DOI
  2. Sturtevant FM. Use of aspartame in pregnancy. Int J Fertil 1985;30:85-7.
  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
  5. Mosnik DM, Spring B, Rogers K, Baruah S. Tardive dyskinesia exacerbated after ingestion of phenylalanine by schizophrenic patients. Neuropsychopharmacology 1997;16:136-46. PubMed
  6. Siddiqui AH, Stolk LM, Bhaggoe R, et al. L-phenylalanine and UVA irradiation in the treatment of vitiligo. Dermatology 1994;88:215-8. PubMed
  7. Birkmayer W, Riederer P, Linauer W, Knoll J. L-deprenyl plus L-phenylalanine in the treatment of depression. J Neural Transm 1984;59:81-7. PubMed
  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
  14. Food and Nutrition Board, Institute of Medicine. Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids (Macronutrients). Washington, DC: National Academy Press, 2002. Available at: http://www.n
  15. Cederbaum S. Phenylketonuria: an update. Curr Opin Pediatr 2002;14:702-6. PubMed
  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
  20. Cotzias, G. C., Van Woert, M. H., and Schiffer, L. M. Aromatic amino acids and modification of parkinsonism. N Engl.J Med 2-16-1967;276(7):374-379. PubMed
  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 →

Threonine 4 references
  1. Tandan R, Bromberg MB, Forshew D, et al. A controlled trial of amino acid therapy in amyotrophic lateral sclerosis: I. Clinical, functional, and maximum isometric torque data. Neurology 1996;47:1220-6. PubMed
  2. Lee A, Patterson V. A double blind study of L-threonine in patients with spinal spasticity. Acta Neurol Scand 1993;88:334-8. PubMed
  3. Blin O, Pouget J, Aubrespy G, et al. A double-blind placebo controlled trial of L-threonine in amyotrophic lateral sclerosis. J Neurol 1992;239:79-81.
  4. Roufs JB. L-threonine as a symptomatic treatment for amyotrophic lateral sclerosis (ALS). Med Hypotheses 1991;34:20-3. PubMed

See these in context on the Threonine monograph →

Proline 4 references
  1. Jennings A, MacGregor A, Spector T, Cassidy A. Amino acid intakes are associated with bone mineral density and prevalence of low bone mass in women: Evidence from discordant monozygotic twins. J Bone Miner Res. 2016;31(2):326-35. PubMed
  2. Gracia-Marco L, Bel-Serrat S, Cuenca-Garcia M, et al. Amino acids intake and physical fitness among adolescents. Amino Acids. 2017;49(6):1041-1052. PubMed
  3. Jamdar J, Rao B, Netke S, et al. Reduction in tibial shaft fracture healing time with essential nutrient supplementation containing ascorbic acid, lysine, and proline. J Altern Complement Med. 2004;10(6):915-6.
  4. Mehl AA, Damião AO, Viana SD, Andretta CP. Hard-to-heal wounds: a randomised trial of an oral proline-containing supplement to aid repair. J Wound Care 2021;30(1):26-31. PubMed

See these in context on the Proline 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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