Herb & supplement monograph

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

But these pages have grown well beyond that into a full monograph — what Methionine 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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Interaction report

Drugs that interact with Methionine

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

We don’t currently list any known drug interactions for Methionine. This doesn’t guarantee none exist — always confirm with your pharmacist before combining supplements with your medications.

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 Methionine combination — clinical detail, likelihood, evidence level, and citations.
Content is reviewed by licensed HelloPharmacist pharmacists — see our data sources and editorial standards.

Monograph

Methionine: Uses, Safety & Side Effects

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

The bottom line

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 not needed unless directed by a healthcare provider. High doses can cause side effects, so talk to your pharmacist or doctor before using methionine supplements.

Part used: Amino acid (made through fermentation or chemical synthesis for supplements)
Common forms: Capsules, tablets, powder, and as part of amino acid blends; also given intravenously in hospitals

People commonly use it for

Acetaminophen (Tylenol) overdose support
Liver health
Urinary tract acidification
Supporting protein and nutritional needs
General antioxidant support

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

Safety at a glance

OverallUse caution

Usually safe in food amounts, but high-dose supplements may cause side effects and should be used with medical guidance.

PregnancyLikely Safe

When used orally in amounts commonly found in food. There is insufficient reliable information available about the safety of methionine in medical dos...

Read the full pregnancy detail

BreastfeedingLikely Safe

When used orally in amounts commonly found in food. There is insufficient reliable information available about the safety of methionine in medical dos...

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.

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Overview

Methionine is an essential amino acid, which means your body cannot make it and must get it from food. It is one of the building blocks of protein and plays a part in many important chemical reactions in the body.

You can find methionine naturally in protein-rich foods such as meat, fish, eggs, dairy, and some plant foods like Brazil nuts, sesame seeds, and soy. Because it is so common in food, most people who eat a balanced diet get plenty of it.

As a supplement, methionine is sold as capsules, tablets, or powder. It is sometimes included in amino acid blends. In hospitals, a related form is used as part of a known treatment for acetaminophen (Tylenol) poisoning.

How it works

Methionine is needed to build proteins, but it also has other jobs. The body uses it to make a compound called S-adenosylmethionine (SAMe), which helps add chemical "tags" (called methyl groups) to DNA, proteins, and other molecules. These reactions are involved in many basic body processes.

Methionine also helps the body make glutathione, an important antioxidant that protects cells and helps the liver clear out harmful substances. This is one reason it is used in acetaminophen poisoning, where glutathione gets used up.

It can also make the urine slightly more acidic, which is why it has been used for certain urinary issues. Many of these effects are understood from lab and animal research, and not every proposed benefit has been proven in people.

Effectiveness

Does Methionine work?

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

Evidence overview · 16 uses evaluated

1 Possibly effective 15 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 Effective Neural tube birth defects