Major interaction on record — check this product against your medications before combining. Based on 5 of 8 ingredients. Check your meds →
Dietary supplement

OptimalAmino Berry Lemonade Ingredients & Drug Interactions

by Optimal Labs

OptimalAmino Berry Lemonade label
See full label image
Powder Category: Amino Acid/protein
Most serious interaction: Major
Clinical methodology reviewed by · Updated Sep 23, 2026 · Label data from the NIH DSLD
What is this page for?

First and foremost: checking OptimalAmino Berry Lemonade 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

OptimalAmino Berry Lemonade is a dietary supplement by Optimal Labs with 8 active ingredients. Its ingredients are commonly taken for sleep problems, low mood and depression, anxiety.Based on those ingredients, 407 medications have a known interaction with it, the most serious rated major. The ingredients most likely to interact are L-Tryptophan, L-Phenylalanine, L-Threonine. Use the checker below to test your specific medication, or read the full HelloPharmacist Interaction Report.

Jump to a section

Check Your Meds Against OptimalAmino Berry Lemonade by Optimal Labs

Ask about any prescription or over-the-counter medication and we check it for interactions with OptimalAmino Berry Lemonade by Optimal Labs — and tell you which ingredient is responsible.

Pharmacist-reviewed data Checks every ingredient Answer in seconds
Prefer a human? Send your question to our licensed pharmacists — free, answered by email within 24 hours.

HelloPharmacist Scorecard of OptimalAmino Berry Lemonade by Optimal Labs

Our pharmacy team’s full take, with four database checks built into the cards below — a summary of what is known, not a grade of the product itself.

From our pharmacy team — supplement deep dive

Generated from HelloPharmacist’s pharmacist-curated databases and editorial rules · Last generated Jul 11, 2026

What’s inside

Low disclosure
Ingredient Transparency · database check
Low

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

Why this rating?
  • The label discloses an exact amount for 0 of its 8 active ingredients.
  • “OptimalAmino EAA Blend” is a proprietary blend — the label gives one combined amount (10 Gram(s)) without saying how much of each component you get.

OptimalAmino Berry Lemonade contains 8 active amino acids—the building blocks your body uses to make and repair muscle and other tissues. The main ingredients are L-valine, L-leucine, and L-isoleucine (three branched-chain amino acids, or BCAAs, that your muscles use directly); L-tryptophan (a precursor to serotonin, a brain chemical); L-phenylalanine (used to make other neurotransmitters); L-lysine (important for collagen and immune function); L-methionine (involved in methylation reactions throughout your body); and L-threonine (needed for protein synthesis and immune health).

The powder also contains inactive ingredients—citric acid, inulin, natural flavors, stevia (rebaudioside A), silicon dioxide, and fruit and vegetable juice powder—for taste and texture.

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: protein synthesis and muscle recovery.
  • We looked for evidence on: Athletic performance, Muscle strength, Wound healing, Exercise recovery, Lean muscle mass, Post-workout nutrition.
  • The closest evidence on file: Methionine is rated "Insufficient Reliable Evidence To Rate" for Wound healing (Natural Medicines).
  • Also on file: Lysine is rated "Insufficient Reliable Evidence To Rate" for Athletic performance, Muscle strength.
  • Also on file: L-tryptophan is rated "Insufficient Reliable Evidence To Rate" for Athletic performance.

The evidence for these amino acids is mixed and depends on what you're taking them for. L-lysine is possibly effective for cold sores (herpes labialis).

L-methionine is possibly effective for neural tube birth defects, though that's a specialized use tied to pregnancy planning. L-tryptophan shows possibly ineffective evidence for depression.

For the other potential uses listed in our data—ADHD, anxiety, athletic performance, bruxism, and premenstrual dysphoric disorder—the evidence is insufficient or the amino acids haven't been studied enough to draw conclusions. If you're considering this for a specific condition, check with your pharmacist or doctor about what the evidence actually supports.

The evidence, ingredient by ingredient L-tryptophan Phenylalanine Lysine Methionine Threonine

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 5 of the 5 matched ingredients.
  • Pregnancy & breastfeeding safety ratings cover 5 of 5.
  • General safety write-ups exist for 5 of 5.
  • Remember: this measures how much safety information exists. Thin data is not the same as being safe.

L-tryptophan is generally well tolerated but has a serious history: a contaminated batch from a single Japanese manufacturer in 1989 caused over 1,500 cases of eosinophilia-myalgia syndrome (EMS), a rare neurological disorder affecting muscles and connective tissue. Today's products are regulated more carefully, but caution is warranted.

Common side effects from L-tryptophan include belching, diarrhea, drowsiness, dry mouth, flatulence, headache, heartburn, lightheadedness, nausea, stomach pain, blurred vision, and vomiting. L-phenylalanine commonly causes anxiety, constipation, headache, heartburn, insomnia, nausea, and sedation.

L-lysine and L-methionine are generally well tolerated at typical doses, though high amounts of L-lysine may cause stomach upset, and high-dose L-methionine may raise homocysteine (a risk factor for heart and blood vessel disease). L-threonine may cause headache, diarrhea, gas, or constipation.

Regarding pregnancy and breastfeeding: L-tryptophan and L-phenylalanine should be avoided during pregnancy and breastfeeding due to insufficient safety data. L-methionine is rated likely safe during pregnancy and lactation.

L-lysine, L-threonine, and the three BCAAs lack sufficient study in pregnancy or breastfeeding—talk with your doctor or pharmacist before using at supplement doses if you're pregnant or nursing.

Side effects, ingredient by ingredient L-tryptophan Phenylalanine Lysine Methionine Threonine

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 5 matched ingredients can interact with medications — Lysine, L-tryptophan, Phenylalanine, Threonine.
  • The most serious interaction on file is rated Major.
  • Some involve high-stakes drug classes: Parkinson's medications.
  • For scale: 407 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 OptimalAmino, double-check with your pharmacist if you're on CNS depressants (sedatives, sleep aids, strong pain relievers)—L-tryptophan could intensify drowsiness. Serotonergic drugs (antidepressants, especially SSRIs and SNRIs) need checking too.

Levodopa for Parkinson's disease can lose effectiveness because of L-phenylalanine. Baclofen (a muscle relaxant) absorption may drop.

MAOIs (older antidepressants like phenelzine or tranylcypromine) carry a risk of dangerous blood pressure spikes. NMDA antagonists like memantine may become less effective because of L-threonine.

And 5-HT4 agonists (used for some GI and neurological conditions) may be affected by L-lysine.

Check your own medication Run your meds through the checker above

The bottom line

Scorecard at a glanceFormula with limited ingredient disclosure with no established evidence rating for its marketed use. Major medication interactions have been identified, and safety information is well characterized.

OptimalAmino is a blend of essential amino acids used to support muscle protein synthesis and general amino acid intake. It's best for people who understand they're taking a supplement with amino acids that have drug interactions—especially anyone on sedatives, antidepressants, Parkinson's medications, muscle relaxants, or older antidepressants.

If you take any prescription medications, check them against the interaction tool on this page, and talk with your pharmacist before starting.

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

Assessment coverage: 5 of 8 active ingredients matched to our full ingredient reviews (monographs). Based on the product label dated Jul 18, 2023.

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 OptimalAmino Berry Lemonade, straight from the product label.

Brand Optimal Labs
Barcode (UPC) 195893137060
Net contents 390 Gram(s); 13.76 Ounce(s)
Market status On market
Date entered into DSLD Jul 18, 2023
DSLD ID 295109
Product type Amino Acid/protein
Supplement form Powder
Dietary claims / uses Nutrient, All Other, Structure/Function
Intended target group(s) Vegan, Vegetarian, Adult (18 - 50 Years), Women (not pregnant or lactating), Gluten Free, 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 OptimalAmino Berry Lemonade by Optimal Labs, 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:
13 Gram(s)
Maximum serving Sizes:
13 Gram(s)
Servings per container
30
UPC/BARCODE
195893137060
IngredientAmount% DV
L-Valine0 NP--
L-Leucine0 NP--
L-Isoleucine0 NP--
L-Tryptophan0 NP--
L-Phenylalanine0 NP--
L-Lysine0 NP--
L-Methionine0 NP--
L-Threonine0 NP--
OptimalAmino EAA Blend10 Gram(s)--

Other ingredients: Citric Acid, Inulin, Natural Flavors, Rebaudioside A, Silicon Dioxide, Fruit and Vegetable Juice, Powder

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.
Formula

What is Optimal Amino? OptimalAmino is a calorie-efficient protein replacement that provides a unique blend of eight essential amino acids (EAAs) in an optimal ratio clinically formulated to achieve 99% utilization for body protein synthesis. Clinical research demonstrates that the EAA formula in OptimalAmino is fully absorbed with 23 minutes and provides 2-6x greater utilization than protein from animal and plant-based protein sources with significantly less calories.

Non-GMO, vegan/paleo/keto-friendly

Suggested/Recommended/Usage/Directions

Suggested use: As a dietary supplement, take 2-3 scoops of OptimalAmino in 12-16 oz of cold water daily. As an exercise recovery aid, take 2-3 scoops of OptimalAmino in 12-16 oz of cold water 30 minutes before resistance training or within 30 minutes of completing endurance exercise. On hard training days or days of minimal dietary protein intake, take 2 scoops up to three times daily. For best results: Use OptimalAmino at least 20 minutes before or 1 hour after consuming other dietary protein or fat.

Precautions

Warning: Not intended for persons under the age of 18.

Do not use if pregnant or nursing. Consult a health care professional prior to consumption if you have any pre-existing medical conditions or are taking any prescription medication.

Improper use of this product will not improve results and is potentially hazardous to a person's health. Use only as directed.

Keep out of reach of children.

Storage

Store in a cool, dry place.

Formulation

Optimal EAA ratio clinically-formulated for 99% utilization EAA formula rapidly absorbed within 23 minutes Increases muscle protein synthesis Improves whole-body protein balance

Non-GMO, vegan/paleo/keto-friendly No artificial flavors or sweeteners

Non-GMO, vegan/paleo/keto-friendly

US manufactured in a cGMP facility

Does not contain: Animal products, corn, dairy, egg, fat, gluten, GMOs, preservatives, rice, sodium, soy, sugar, wheat, whey, or yeast.

The amount of product contained in 2 scoops may be above or below 13 grams due to variations in handling and product density.

FDA Statement of Identity

Dietary Supplement

Seals/Symbols

NSF Certified Sport

Manufactured in the U.S.A.

General Statements

Contents sold by weight, not volume. Some settling may occur during shipping and handling.

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.

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

See for yourself

OptimalAmino Berry Lemonade by Optimal Labs label

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

OptimalAmino Berry Lemonade 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 OptimalAmino Berry Lemonade by Optimal Labs

These are the 8 active ingredients this product is made of. Select any to open its full monograph.

Serving size13 Gram(s) Dosage formPowder 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.

OptimalAmino EAA Blend

10 Gram(s) per serving

Other (inactive) ingredients: Citric Acid, Inulin, Natural Flavors, Rebaudioside A, Silicon Dioxide, Fruit and Vegetable Juice, Powder. These complete the product’s ingredient list but are not active constituents.

Interaction report

OptimalAmino Berry Lemonade by Optimal Labs Drug Interactions

Want to check YOUR meds against OptimalAmino Berry Lemonade?

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
407Drugs
256 Major 151 Moderate

Ingredients driving the most interactions

L-Tryptophan 394
L-Phenylalanine 16
L-Threonine 3
L-Lysine 1

Individual Drug Interactions

The ingredients in OptimalAmino Berry Lemonade interact with 407 drugs. Click any drug to see the details.

4 of the 8 ingredients in OptimalAmino Berry Lemonade interact with drugs. Each result below shows which ingredient is responsible. L-Tryptophan L-Phenylalanine L-Threonine L-Lysine

Each ingredient & the kinds of drugs it affects

For each ingredient in OptimalAmino Berry Lemonade 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-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
L-Tryptophan 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

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-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 OptimalAmino Berry Lemonade, from the product label.

Optimal Labs

See all Optimal Labs products
Name
Optimal Labs, LLC.
Street Address
722 E. Market St. STE 102 # V40
City
Leesburg
State
VA
ZipCode
20176
Web Address
www.OptimalAmino.com
Pharmacist Counseling Corner

OptimalAmino Berry Lemonade by Optimal Labs: Common Questions

Does OptimalAmino Berry Lemonade by Optimal Labs interact with any medications?
Yes. Based on its ingredients, OptimalAmino Berry Lemonade has a known interaction with 407 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?
OptimalAmino Berry Lemonade contains 8 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 OptimalAmino if I'm pregnant or breastfeeding?
L-tryptophan and L-phenylalanine should be avoided—safety data is not established. L-methionine is rated likely safe during pregnancy and breastfeeding. L-lysine, L-threonine, and the three BCAAs haven't been well studied at supplement doses during pregnancy or breastfeeding. Talk with your doctor or pharmacist for personalized advice before using this product if you're pregnant or nursing.
What's L-tryptophan, and why should I worry about it?
L-tryptophan is an amino acid your body uses to make serotonin, a brain chemical linked to mood and sleep. It's generally well tolerated, but in 1989 a contaminated batch caused a rare neurological disorder affecting over 1,500 people. Today's products are regulated more carefully. The main concern now is that it can add drowsiness if you're also taking sedatives or other CNS depressants.
Will OptimalAmino help me build muscle or recover from workouts?
The product contains branched-chain amino acids (L-valine, L-leucine, L-isoleucine) and other amino acids that support muscle protein synthesis. However, the data we hold shows insufficient evidence for athletic performance specifically—meaning we don't have strong trial evidence proving it works for that goal.
What are the most common side effects?
L-tryptophan commonly causes belching, diarrhea, drowsiness, dry mouth, flatulence, headache, heartburn, lightheadedness, nausea, stomach pain, blurred vision, and vomiting. L-phenylalanine often causes anxiety, constipation, headache, heartburn, insomnia, nausea, and sedation. L-lysine may cause abdominal pain, diarrhea, and stomach upset. High doses are more likely to cause problems.
Does OptimalAmino work for depression or anxiety?
L-tryptophan shows possibly ineffective evidence for depression, and evidence for anxiety is insufficient—meaning it hasn't been well studied enough to know if it works. Don't rely on this product as a treatment for mood or anxiety disorders; talk with your doctor about proven options.
Is there anything I need to know about the inactive ingredients?
The powder contains citric acid, inulin, natural flavors, stevia (rebaudioside A), silicon dioxide, and fruit and vegetable juice powder. These are fillers, binders, and flavorings. If you have sensitivities to any of these, check the label or ask your pharmacist.

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

Not sure if OptimalAmino Berry Lemonade 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.

OptimalAmino Berry Lemonade label
Go deeper

The Full Monographs Behind OptimalAmino Berry Lemonade’s Ingredients

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

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

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

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

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

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 →
Sources

Sources & How We Checked

OptimalAmino Berry Lemonade'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 64 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-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 →

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

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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 →

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 →

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 →

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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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