No known drug interactions for the matched ingredients — not a guarantee none exist. Check your meds →
Dietary supplement

L-Methionine Ingredients & Drug Interactions

by Douglas Laboratories

L-Methionine label
See full label image
Capsule Category: Amino Acid/protein
No known interaction
Clinical methodology reviewed by · Updated Sep 9, 2026 · Label data from the NIH DSLD
What is this page for?

First and foremost: checking L-Methionine 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 No known interaction

L-Methionine is a dietary supplement by Douglas Laboratories with 1 active ingredient. Its ingredients are commonly taken for acetaminophen (tylenol) overdose support, liver health, urinary tract acidification.We don’t currently list a known drug interaction for its mapped ingredients — but that doesn’t guarantee none exist, so always confirm with your pharmacist.

Jump to a section

HelloPharmacist Scorecard of L-Methionine by Douglas Laboratories

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-Methionine, an amino acid your body uses to build proteins and support various metabolic processes. The capsule also contains inactive ingredients — gelatin, magnesium silicate, vegetable stearate, and microcrystalline cellulose — which are standard binders and fillers.

Does it work?

Moderate 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 Methionine's overall clinical evidence instead.

Moderate

Some clinical evidence supports Methionine 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 ingredient's overall clinical evidence instead.
  • On file: Neural tube birth defects — rated "Possibly Effective" (Natural Medicines).

The evidence we hold is mixed. L-Methionine is rated possibly effective for neural tube birth defects — a critical finding if you're planning pregnancy or currently pregnant.

For acetaminophen (Tylenol) poisoning, asthma, hay fever, and colorectal cancer, the evidence isn't strong enough in our data to rate it either way. If you're considering this supplement for any of those uses, talk with your doctor about whether the current evidence supports it for your situation.

The evidence, ingredient by ingredient Methionine

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.

When you eat methionine in normal food amounts, it's well tolerated. High-dose supplements, though, may cause side effects — dizziness, drowsiness, irritability, vomiting, or headache — and warrant medical guidance before you start.

During pregnancy, normal dietary amounts are fine, but supplement doses haven't been proven safe, so talk with your doctor if you're pregnant or planning to become pregnant. Breastfeeding safety of supplement doses is not well studied; check with your doctor or pharmacist before taking a supplement while nursing.

Side effects, ingredient by ingredient Methionine

Meds to double-check

No known interactions
Known Interaction Concern · database check
No known interactions

No medication interactions are currently documented for the matched ingredients — that isn't a guarantee none exist.

Why this rating?
  • None of the 1 matched ingredient has a documented medication interaction on file.

No interactions are documented for L-Methionine in our data. Even so, if you take any prescription medications, check them against the search tool on this page before starting — and mention this supplement to your doctor or pharmacist at your next visit.

The bottom line

Scorecard at a glanceFully disclosed formula with some supporting evidence behind its ingredients' uses. No medication interactions are currently documented, and safety information is well characterized.

L-Methionine may be worth considering if you're interested in neural tube birth defect prevention or if your doctor has suggested it for another reason. Because high-dose supplements can cause side effects and may raise homocysteine levels, use it under medical guidance, especially if you have a history of heart or blood vessel disease.

Talk with your doctor or pharmacist about whether this supplement is right for you and what dose makes sense.

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 Aug 23, 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-Methionine, straight from the product label.

Brand Douglas Laboratories
Barcode (UPC) 310539001028
Net contents 60 Capsule(s)
Market status On market
Date entered into DSLD Aug 23, 2020
DSLD ID 232443
Product type Amino Acid/protein
Supplement form Capsule
Dietary claims / uses All Other, Structure/Function
Intended target group(s) Adult (18 - 50 Years), Gluten 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-Methionine by Douglas Laboratories, 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 Capsule(s)
Maximum serving Sizes:
1 Capsule(s)
Servings per container
60
UPC/BARCODE
310539001028
IngredientAmount% DV
L-Methionine500 mg--

Other ingredients: Gelatin, Magnesium Silicate, Vegetable Stearate, Microcrystalline Cellulose

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.
Suggested/Recommended/Usage/Directions

Suggested Usage: As a dietary supplement, adults take 1 capsule daily or as directed by your health professional.

Precautions

Warning: If you are pregnant, nursing, have any health condition or taking any medication, consult your health professional before using this product.

Keep out of the reach of children.

Use only if safety seal is intact.

Storage

Store in a cool, dry place.

Formulation

Gluten-free, Non-GMO

FDA Disclaimer Statement

This statement has not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.

General Statements

Scan to learn about our manufacturing excellence Contents may not fill package in order to accommodate required labeling. Please rely on stated quantity.

FDA Statement of Identity

Dietary Supplement

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

See for yourself

L-Methionine by Douglas Laboratories label

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

L-Methionine 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-Methionine by Douglas Laboratories

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

Serving size1 Capsule(s) Dosage formCapsule Servings per container60 Amounts shown are per serving.

L-Methionine

No known
interactions
500 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...

L-Methionine monograph & interactions

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

Interaction report

L-Methionine by Douglas Laboratories Drug Interactions

We don’t currently list any known drug interactions for the mapped ingredients in L-Methionine. This doesn’t guarantee none exist — always confirm with your pharmacist before combining a supplement with your medications.

The maker

Brand information

Manufacturer and brand details for L-Methionine, from the product label.

Douglas Laboratories

See all Douglas Laboratories products
Name
Douglas Laboratories
Street Address
600 Boyce Road
City
Pittsburgh
State
PA
ZipCode
15205
Phone Number
1.800.245.4440
Web Address
www.douglaslabs.com
Pharmacist Counseling Corner

L-Methionine by Douglas Laboratories: Common Questions

Does L-Methionine by Douglas Laboratories interact with any medications?
We do not currently list a known interaction for the mapped ingredients in L-Methionine. This does not guarantee none exist, so confirm with your pharmacist.
How can one product interact with so many drugs?
L-Methionine 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.
Is L-Methionine safe to take if I'm pregnant?
Normal dietary amounts of methionine are fine during pregnancy, but supplement doses haven't been proven safe. If you're pregnant or planning to become pregnant, talk with your doctor or pharmacist before taking a supplement — especially if you're interested in it for birth defect prevention.
Can L-Methionine help prevent birth defects?
L-Methionine is rated possibly effective for neural tube birth defects, but that's a decision that belongs with your doctor, not a substitute for their guidance. If you're planning pregnancy or currently pregnant and interested in this supplement, discuss it with your prenatal care provider.
What are the most common side effects?
When used in food amounts, methionine is well tolerated. High-dose supplements may cause dizziness, drowsiness, irritability, vomiting, or headache. Because of these risks and the potential to raise homocysteine levels, use supplement doses only under medical guidance.
Is it safe to breastfeed while taking L-Methionine supplements?
Food amounts of methionine are expected to be fine while breastfeeding, but the safety of supplement doses isn't well studied. Talk with your doctor or pharmacist before taking a supplement while nursing.
Does L-Methionine interact with any medications?
No interactions are documented in our data for L-Methionine. Still, it's a good idea to check your specific medications with the search tool on this page or mention this supplement to your doctor or pharmacist before you start.

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

Not sure if L-Methionine 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.

L-Methionine label
Go deeper

The Full Monographs Behind L-Methionine’s Ingredients

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

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 →
Sources

Sources & How We Checked

L-Methionine'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 12 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.

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 →

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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