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Dietary supplement

L-Threonine 500 mg Ingredients & Drug Interactions

by Solgar

L-Threonine 500 mg label
See full label image
Capsule Category: Amino Acid/protein
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 L-Threonine 500 mg 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

L-Threonine 500 mg is a dietary supplement by Solgar with 1 active ingredient. Its ingredients are commonly taken for general amino acid/protein support, muscle and tissue health, immune support.Based on those ingredients, 3 medications have a known interaction with it, the most serious rated major. The ingredients most likely to interact are 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 L-Threonine 500 mg by Solgar

Ask about any prescription or over-the-counter medication and we check it for interactions with L-Threonine 500 mg by Solgar — and tell you which ingredient is responsible.

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HelloPharmacist Scorecard of L-Threonine 500 mg by Solgar

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 Aug 13, 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 1 of its 1 active ingredient.
  • No proprietary blends here — you can verify the dose of every single component.

This product contains one active ingredient: L-threonine, a 500 mg dose of an amino acid your body uses to build and repair tissues. The capsule also contains vegetable cellulose, stearic acid, and vegetable magnesium stearate — these are inactive ingredients that help form and stabilize the capsule.

Does it work?

Couldn't assess
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 assessable

This is a single-ingredient Threonine product and its label doesn't state a use — see Threonine's own graded uses on its monograph.

Why this rating?
  • We looked at the product name, claims, and label statements and couldn't find a stated purpose to grade.

L-threonine has been studied for several neurological conditions. For amyotrophic lateral sclerosis (ALS, Lou Gehrig's disease), current evidence suggests it's possibly ineffective.

For multiple sclerosis, spasticity, and familial spastic paraparesis, there isn't enough reliable evidence in our data to say whether it works or doesn't.

The evidence, ingredient by ingredient 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 1 of the 1 matched ingredient.
  • Pregnancy & breastfeeding safety ratings cover 1 of 1.
  • General safety write-ups exist for 1 of 1.
  • Remember: this measures how much safety information exists. Thin data is not the same as being safe.

Threonine from food is well tolerated, but supplement safety at higher doses like 500 mg hasn't been well studied. Common side effects reported in people taking threonine include headache and mild stomach upset — some have experienced diarrhea, gas, or constipation.

Supplement use in pregnancy and while breastfeeding hasn't been well studied; the safety data advises against taking it during these times unless your doctor has advised otherwise. Talk with your doctor or pharmacist before using this product if you're pregnant or nursing.

Side effects, ingredient by ingredient 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?
  • 1 of the 1 matched ingredient can interact with medications — Threonine.
  • The most serious interaction on file is rated Major.
  • For scale: 3 individual medications appear in the full list. A big number alone doesn't make a product dangerous — what matters is whether YOUR medication is on it, so run yours through the interaction checker on this page.

Before taking this product, check with your doctor or pharmacist if you take any NMDA antagonist medications (such as memantine or ketamine). These drugs may become less effective when used with L-threonine.

No other medication interactions are documented in our data for this ingredient.

Check your own medication Run your meds through the checker above

The bottom line

Scorecard at a glanceFully disclosed formula with no assessable stated purpose. Major medication interactions have been identified, and safety information is well characterized.

L-threonine is a single-ingredient amino acid supplement that's most relevant if you're looking at it for neurological conditions — though the evidence for those uses is limited or unclear. The main caution is if you take NMDA antagonist medications; you'll need to check with your doctor or pharmacist first.

If you're pregnant, breastfeeding, or have any ongoing health condition or medications, run this by your own healthcare provider before you start.

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

Assessment coverage: 1 of 1 active ingredient matched to our full ingredient reviews (monographs). Based on the product label dated Mar 24, 2020.

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 L-Threonine 500 mg, straight from the product label.

Brand Solgar
Barcode (UPC) 033984027107
Net contents 100 Vegetable Capsule(s)
Market status On market
Date entered into DSLD Mar 24, 2020
DSLD ID 214993
Product type Amino Acid/protein
Supplement form Capsule
Dietary claims / uses Nutrient, All Other
Intended target group(s) Vegetarian, Adult (18 - 50 Years), Kosher, Gluten Free, Dairy Free, Sugar 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 L-Threonine 500 mg by Solgar, sourced from the NIH Dietary Supplement Label Database.

Supplement Facts

Daily Value (DV) Target Group(s):
Adults and children 4 or more years of age
Minimum serving Sizes:
1 Vegetarian Capsule(s)
Maximum serving Sizes:
1 Vegetarian Capsule(s)
UPC/BARCODE
033984027107
IngredientAmount% DV
L-Threonine500 mg--

Other ingredients: Vegetable Cellulose, Stearic Acid, Vegetable Magnesium Stearate

Tap any ingredient to jump to its full detail below.

Label statements
These statements are the manufacturer’s wording, reproduced from the product label — the label is saying it, not HelloPharmacist. We don’t verify or endorse them.
Formulation

Solgar's L-Threonine Vegetable Capsules are free of corn, yeast, wheat, soy, gluten and dairy products and are formulated without the use of artificial preservatives, flavors or colors.

(Free form)

Suitable for vegetarians

Sugar, salt and starch free

L-Threonine is an essential amino acid. Long chains of molecularly bonded individual amino acids form protein. The body must first break these molecular (peptide) bonds for amino acid absorption to take place. Solgar's free form amino acids are already in their simplest form (no peptide bonds) and can be readily absorbed into the bloodstream.

Storage

To assure freshness and potency, store at room temperature 59 degrees-86 degrees F (15 degrees-30 degrees C). Store away from heat, light and moisture.

Formula

Solgar's KOF-K certification #K-1250

Precautions

Do not use if outer bottle seal is missing, torn or damaged in any way.

If you are pregnant, nursing, taking any medication or have a medical condition, please consult your healthcare practitioner before taking any dietary supplement.

Keep out of reach of children.

General Statements

Solgar since 1947

FDA Statement of Identity

Dietary Supplement

Seals/Symbols

K Parve (Kosher)

Suggested/Recommended/Usage/Directions

Suggested Use: As a dietary supplement for adults, take one (1) vegetable capsule daily with juice or water, between meals, or as directed by a healthcare practitioner.

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

See for yourself

L-Threonine 500 mg by Solgar label

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

L-Threonine 500 mg 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 L-Threonine 500 mg by Solgar

This is the 1 active ingredient this product is made of. Select it to open its full monograph.

Serving size1 Vegetarian Capsule(s) Dosage formCapsule Amounts shown are per serving.

L-Threonine

Interacts with
3 drugs
500 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...

L-Threonine monograph & interactions

Other (inactive) ingredients: Vegetable Cellulose, Stearic Acid, Vegetable Magnesium Stearate. These complete the product’s ingredient list but are not active constituents.

Interaction report

L-Threonine 500 mg by Solgar Drug Interactions

Want to check YOUR meds against L-Threonine 500 mg?

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
3Drugs
3 Major

Ingredients driving the most interactions

L-Threonine 3

Individual Drug Interactions

The ingredients in L-Threonine 500 mg interact with 3 drugs. Click any drug to see the details.

1 of the 1 ingredient in L-Threonine 500 mg interact with drugs. Each result below shows which ingredient is responsible. L-Threonine

Each ingredient & the kinds of drugs it affects

For each ingredient in L-Threonine 500 mg with known interactions, here are the types of medications it can affect. Open any type for the detail — or search your exact drug in the checker above.

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
The maker

Brand information

Manufacturer and brand details for L-Threonine 500 mg, from the product label.

Solgar

See all Solgar products
Name
Solgar Vitamin and Herb
City
Leonia
State
N.J.
ZipCode
07605
Phone Number
1-877-765-4274
Web Address
www.solgar.com
Pharmacist Counseling Corner

L-Threonine 500 mg by Solgar: Common Questions

Does L-Threonine 500 mg by Solgar interact with any medications?
Yes. Based on its ingredients, L-Threonine 500 mg has a known interaction with 3 medications, including 3 rated major. Use the checker to see how it interacts with a specific drug.
How can one product interact with so many drugs?
L-Threonine 500 mg contains a single active ingredient, and that one ingredient can interact with many different medications on its own. We check it against each medication and show the mechanism 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 L-threonine if I'm pregnant?
Supplement-dose threonine hasn't been well studied in pregnancy. The safety data advises against it unless your doctor has told you it's okay. Talk with your doctor or pharmacist for personalized advice based on your situation.
What side effects might I notice?
Headache is the most common one reported. Some people also notice mild stomach upset — diarrhea, gas, or constipation — though these are not universal. If a side effect bothers you, mention it to your pharmacist.
Does this really work for ALS or multiple sclerosis?
For ALS, the evidence we hold suggests it's possibly ineffective. For MS, we don't have enough reliable evidence to say whether it works. If you're considering it for either condition, talk it over with your doctor — they'll know your specific situation.
What exactly is L-threonine?
It's an amino acid — one of the building blocks your body uses to make proteins and repair tissues. You get small amounts from foods like meat, dairy, and eggs; this supplement provides a larger concentrated dose.
Can I breastfeed while taking this?
Supplement-dose threonine hasn't been well studied during breastfeeding. Check with your doctor or pharmacist before you use it if you're nursing.

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

Not sure if L-Threonine 500 mg is safe with your meds?

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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.

L-Threonine 500 mg label
Go deeper

The Full Monographs Behind L-Threonine 500 mg’s Ingredients

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

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

L-Threonine 500 mg'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 4 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.

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 →

Parts of this content are provided by the Therapeutic Research Center, LLC.

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

© 2021 Therapeutic Research Center, LLC

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