Herb & supplement monograph

Threonine Drug Interactions, Uses, Effectiveness, Safety & More

Medically reviewed by Dr. Brian Staiger, PharmD, BCPS ·Updated July 2026

What is this page for?

First and foremost: how Threonine interacts with medications. The heart of this page is the interaction list — every drug Threonine is known to interact with, and how serious each one is.

But these pages have grown well beyond that into a full monograph — what Threonine is, what people use it for and how strong the evidence is, its safety and side effects, and answers to the questions we’re asked most — written and reviewed by the clinical staff at HelloPharmacist. It’s educational information from our licensed clinical databases, not medical advice, and we don’t sell or endorse products. Our editorial policy

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Reviewed by licensed pharmacists Sourced from Natural Medicines

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Interaction report

Drugs that interact with Threonine

3 medications have a known interaction with Threonine, graded by severity. Select any drug for the full evidence-based detail.

3 major interactions. These combinations can be clinically significant — best avoided, or used only with close professional supervision. Always check with your pharmacist before combining them with Threonine.

Don’t want to scroll the list? Just ask.

Tell us the medications you take and we’ll check each one against Threonine using our pharmacist-reviewed interaction data.

AI summaries are generated from our Threonine interaction data for education only — always confirm with your pharmacist. How we use AI

2,830 drugs

Read The List Like a Pharmacist

What Severity, Likelihood & Evidence Mean

Severity — How Serious It Can Be

Major. Clinically significant; generally best avoided, or used only under direct professional supervision.
Moderate. May need monitoring, a dose adjustment, or separating the times you take each one.
Minor. Generally not clinically significant, but still worth noting and mentioning to your pharmacist.
No known interaction. Checked against our sources with nothing documented — not the same as proven safety.

Likelihood — How Well It’s Documented

Likely. Well-controlled human studies have demonstrated the likely existence of this interaction
Probable. Interaction has not been documented in well-controlled studies, however, the interaction has been demonstrated in some small human studies or in controlled animal studies in conjunction with multiple case reports.
Possible. Interaction has been documented in animal or in lab research, or the interaction has been documented in humans but is limited to case reports or conflicting clinical research exists
Unlikely. Interaction has been demonstrated in animal or in lab research but has been shown not to occur in humans.

Where This Data Comes From

Interaction records are evidence-graded and sourced from the Natural Medicines database (TRC Healthcare), the same reference used by pharmacists and hospitals.
Each drug listed above links to the full report for that exact Threonine combination — clinical detail, likelihood, evidence level, and citations.
Content is reviewed by licensed HelloPharmacist pharmacists — see our data sources and editorial standards.

The big picture

The kinds of drugs Threonine affects

Every type of medication (drug category) Threonine is known to interact with. Open any category for the detail — or search your exact drug in the checker above.

All 1 drug category Threonine interacts with

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

Monograph

Threonine: Uses, Safety & Side Effects

Medically reviewed by Dr. Brian Staiger, PharmD, BCPS · Reviewed July 2026 ·

The bottom line

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 taking it as a separate supplement is limited. If you are considering threonine supplements, talk with your pharmacist or doctor first.

Part used: Amino acid (obtained from dietary protein or made synthetically)
Common forms: Capsules, tablets, powder, and part of amino acid blends; also found in protein-rich foods

People commonly use it for

General amino acid/protein support
Muscle and tissue health
Immune support
Nervous system support (as a precursor)
Liver health (proposed)

Popular and traditional uses — not proof it works. See “Uses & effectiveness” below for the evidence.

Safety at a glance

OverallUse caution

Threonine from food is safe; supplement safety at higher doses is not well studied.

PregnancyInsufficient reliable information

Insufficient reliable information available; avoid using.

Read the full pregnancy detail

BreastfeedingInsufficient reliable information

Insufficient reliable information available; avoid using.

Read the full breastfeeding detail

Pregnancy & breastfeeding ratings are from Natural Medicines (Therapeutic Research Center). Safety guidance is general; always confirm with your pharmacist or doctor for your situation.

Jump to a section

Overview

Threonine (often written as L-threonine) is one of the essential amino acids. Essential means your body cannot make it on its own, so you have to get it from the food you eat. It is found naturally in protein-rich foods such as meat, fish, eggs, dairy, beans, nuts, and seeds.

Inside the body, threonine is used as a building block to make proteins. It is part of tissues like collagen, elastin, and muscle. Most people who eat a balanced diet already get enough threonine and do not need a supplement.

Threonine is also sold on its own or as part of amino acid blends in capsules, tablets, and powders. People take these products hoping to support muscle, immune health, or the nervous system, though the evidence for these uses is limited.

How it works

Threonine is a building block (a monomer) that the body links together with other amino acids to form proteins. It is especially common in structural proteins like collagen and elastin, which support skin, connective tissue, and other body parts.

It also plays a role in making mucus that protects the gut lining, supports normal immune function, and helps the body balance nitrogen. In the body, threonine can be converted into other useful molecules, including the amino acid glycine, which is active in the nervous system.

Much of what we know about these roles comes from basic nutrition science and animal research. How extra threonine from a supplement behaves in healthy people is less clear.

Effectiveness

Does Threonine work?

Here’s what the research actually shows for each use — graded by Natural Medicines and reviewed by Dr. Brian Staiger, PharmD.

Evidence overview · 4 uses evaluated

1 Leans ineffective 3 Insufficient evidence

How to read these evidence grades

Natural Medicines’ 7-point scale. We show each rating’s label word-for-word.

1EffectiveStrong, consistent evidence it works.

2Likely EffectiveGood evidence, though not yet conclusive.

3Possibly EffectiveSome evidence suggests a benefit.

4Possibly IneffectiveSome evidence it may not help.

5Likely IneffectiveFairly strong evidence it doesn’t help.

6IneffectiveStrong evidence it doesn’t work.

7Insufficient Reliable Evidence to RateToo little research to say either way.

Possibly Ineffective Amyotrophic lateral sclerosis (ALS, Lou Gehrig's disease)

Rating & evidence shown verbatim from Natural Medicines

Several small clinical studies suggest that oral threonine does not improve symptoms or slow the progression of ALS.

Also studied for 3 conditions — evidence insufficient to rate

Insufficient Reliable Evidence To Rate Familial spastic paraparesis (FSP)

Rating & evidence shown verbatim from Natural Medicines

It is unclear if oral threonine is beneficial in patients with FSP.

Insufficient Reliable Evidence To Rate Multiple sclerosis (MS)

Rating & evidence shown verbatim from Natural Medicines

It is unclear if oral threonine is beneficial in patients with MS.

Insufficient Reliable Evidence To Rate Spasticity

Rating & evidence shown verbatim from Natural Medicines

It is unclear if oral threonine is beneficial in patients with spasticity.

Source & disclaimer. Effectiveness ratings and evidence summaries are provided by Natural Medicines (Therapeutic Research Center) and shown as licensed. Where Natural Medicines hasn’t rated a use, HelloPharmacist’s pharmacists may add their own reviewed rating and evidence (each such entry is labeled). This is educational information, not medical advice — talk with your pharmacist or doctor before starting, stopping, or changing a supplement.

Safety & precautions

Threonine obtained from a normal diet is considered safe — it is a natural part of the food we eat every day. The safety of taking larger amounts as a supplement over a long time has not been well studied.

People with kidney or liver disease should be cautious, because these organs process amino acids, and high amino acid loads may be harder for them to handle. If you have any chronic health condition, check with your doctor or pharmacist before starting.

For pregnancy and breastfeeding, normal dietary amounts are fine and expected, but supplement-level doses have not been well studied. To be safe, avoid threonine supplements during pregnancy and breastfeeding unless your healthcare provider specifically recommends them.

Side effects

Threonine is generally well tolerated when taken in modest amounts. The most commonly reported side effects are mild stomach complaints, such as nausea, upset stomach, or headache.

Serious side effects are not well documented, but because high-dose, long-term use has not been carefully studied, unexpected effects are possible. Stop using it and contact a healthcare provider if you notice anything unusual, such as an allergic reaction (rash, swelling, or trouble breathing).

Threonine: Reported Adverse Effects

Documented safety reports on Threonine from the evidence-graded Natural Medicines (TRC Healthcare) database, shown word-for-word from the licensed record.

Reports by condition

Cluster headache Neurologic/CNS

Orally, headache has been reported in people who have taken threonine.

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.

Constipation Gastrointestinal

Orally, some patients can experience minor gastrointestinal upset including diarrhea. Other side effects reported in people who have taken threonine include flatus and constipation.

DISCLAIMER: This tool is intended for informational purposes only, and should not be interpreted as specific medical advice. Patients should consult with a qualified healthcare provider before making decisions about therapies and/or health conditions.

Adverse-effects data: Natural Medicines, Therapeutic Research Center

Dosing

There is no well-established standard supplement dose of threonine for general health. Studies that have used it for specific medical conditions used different amounts, and those doses were given under medical supervision.

If you choose to use a threonine product, follow the directions on the label and do not exceed the recommended amount. Because the right dose depends on your diet, health, and reasons for using it, it is best to check with a pharmacist or doctor before starting, especially if you have any medical condition.

Pregnancy & Breastfeeding

Threonine & Pregnancy

Insufficient reliable information

Insufficient reliable information available; avoid using.

Threonine & Breastfeeding

Insufficient reliable information

Insufficient reliable information available; avoid using.

Pregnancy & lactation ratings: Natural Medicines, Therapeutic Research Center

References & further reading

The 4 references that drive our Threonine monograph and interaction data, from the evidence-graded Natural Medicines (TRC Healthcare) database. Citations with a link open the study on PubMed or the publisher’s site.

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
Lee A, Patterson V. A double blind study of L-threonine in patients with spinal spasticity. Acta Neurol Scand 1993;88:334-8. PubMed
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.
Roufs JB. L-threonine as a symptomatic treatment for amyotrophic lateral sclerosis (ALS). Med Hypotheses 1991;34:20-3. PubMed

Keep reading

This information is for education only and is not a substitute for professional medical advice. Always check with your pharmacist or doctor before starting, stopping, or combining supplements and medications.

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.

Brand directory

Brands that make products with Threonine

360 brands in our database make a supplement containing Threonine.

'Merica Labz 62 products 1st Phorm 75 products 21st Century 798 products 4 Dimension Nutrition 8 products 4DN 6 products AB American Biologics 76 products Advocare 165 products AdvoCare FIT 2 products Akasha Naturals 20 products All American EFX 14 products Allergy Research Group 1,595 products ALLMAX 210 products Alpha Lion 43 products ALR Industries 5 products Anabolic Warfare 65 products Animal 139 products Anutra 4 products Anutra Grain 1 product Apax USA 3 products Apex 19 products Apollon Nutrition 41 products Applied Nutrition 76 products aProvenProduct 24 products Arms Race Nutrition 145 products

Product directory

Supplement products with Threonine

1,813 products in our database contain Threonine. Open any to see its full ingredient list and every drug interaction we check.

Pharmacist Counseling Corner

Threonine: Common Questions

What is Threonine used for, and does it work?

People use Threonine for a range of reasons, but according to the Natural Medicines database the current clinical evidence is insufficient to confirm it works for the specific conditions it has been studied for. See the graded list on this page, and talk to your pharmacist or doctor before relying on it for any condition.

Does Threonine interact with prescription medications?

Yes. We list 3 medications with a known interaction with Threonine, including 3 rated major. Use the checker above to see how Threonine interacts with a specific drug.

How are Threonine interactions rated?

Each interaction is graded major, moderate, or minor based on how clinically significant it is and the strength of the evidence behind it. Major interactions are the most serious and are best avoided, or used only under close professional supervision.

Is it safe to take Threonine with my medications?

It depends on the specific medication. Some combinations are fine, while others call for monitoring, timing changes, or should be avoided. Check your exact drug above and confirm with your pharmacist or doctor before starting, stopping, or changing anything.

Where does this Threonine interaction information come from?

Our interaction data is built on the Natural Medicines database — an evidence-graded reference for vitamins, herbs, and supplements — and is reviewed by licensed HelloPharmacist pharmacists, who may add clinical context.

What is Threonine used for?

Threonine is an essential amino acid used by the body to build proteins like collagen, elastin, and muscle, and to support immune function. As a supplement, people take it hoping to support muscle, immunity, or the nervous system, but strong human evidence for these uses is limited.

Do I need a Threonine supplement?

Most people get plenty of Threonine from protein-rich foods like meat, fish, eggs, dairy, beans, and nuts, so a supplement usually is not needed. Talk to your pharmacist or doctor if you think you may not be getting enough.

Is Threonine safe to take?

Threonine from food is safe, and supplements are generally well tolerated in modest amounts, though they may cause mild stomach upset or headache. The safety of high doses over a long period has not been well studied, so it is best to check with a healthcare provider.

Can I take Threonine while pregnant or breastfeeding?

Getting Threonine from food is normal and fine, but Threonine supplements have not been well studied in pregnancy or breastfeeding. To be safe, avoid supplements during these times unless your doctor advises otherwise.

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

Keep exploring

Products that contain Threonine

A rotating sample of real supplements in our database that list Threonine — open any to see its full ingredients and every drug interaction we check.

See all 1,813 products with Threonine →

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Threonine Drug Interactions, Uses, Effectiveness, Safety & More

Your Choice:

Drugs that interact with Threonine

Don’t want to scroll the list? Just ask.

What Severity, Likelihood & Evidence Mean

Severity — How Serious It Can Be

Likelihood — How Well It’s Documented

Where This Data Comes From

The kinds of drugs Threonine affects

Threonine: Uses, Safety & Side Effects

Overview

How it works

Does Threonine work?

Safety & precautions

Side effects

Threonine: Reported Adverse Effects

Dosing

Threonine & Pregnancy

Threonine & Breastfeeding

References & further reading

Brands that make products with Threonine

Supplement products with Threonine

Threonine: Common Questions

Related supplements & herbs

Products that contain Threonine

Have a question about Threonine?