Drug & supplement interaction

Methionine + Fluoxetine

Fluoxetine brand names: Prozac, Sarafem.

No Known Interaction
Medically reviewed by · Updated July 2026 · Pair last verified Sep 13, 2026
The bottom line No known interaction

We found no known interaction between Methionine and Fluoxetine in our sources. Absence of a documented interaction is not the same as proven safety, and does not guarantee one does not exist. Do not start, stop, or change a medication or supplement based on this page; confirm with your pharmacist or doctor first. Additionally, although there is no interaction, the two are separately associated with some of the same side effects, which would make a new symptom harder to attribute to one or the other.

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Interaction report

Methionine and Fluoxetine

We checked these two against our interaction database. Here is what we found.

No Known Interaction Found

We did not find a documented interaction between Fluoxetine and Methionine in our sources. This does not guarantee that the combination is completely free of risk — there is often limited research on supplements and herbal products, especially around drug interactions.

Worth understanding: our licensed dataset holds no drug-interaction record for Methionine at all — not against Fluoxetine, and not against any other medication we track. This verdict therefore rests on the absence of any recorded data, not on research that looked at this combination and found nothing. We cannot rule an interaction out.

If you decide to take both, the practical routine is simple: add one new thing at a time and note the date you started it. If the combination is going to disagree with you, it usually shows in the first days to a couple of weeks — and a start date turns “I’ve been feeling off” into something a pharmacist can actually work with. Do not stop a prescribed medicine on your own.

Always talk with your pharmacist or doctor before making changes to your medications or supplements, particularly if you take several medications or have an ongoing health condition.

Methionine safety at a glance

Methionine overall Use caution Usually safe in food amounts, but high-dose supplements may cause side effects and should be used with medical guidance.
Pregnancy Likely Safe When used orally in amounts commonly found in food. There is insufficient reliable information available about the safety of methionine in medical doses during... Read the full pregnancy detail
Breastfeeding Likely Safe When used orally in amounts commonly found in food. There is insufficient reliable information available about the safety of methionine in medical doses during... Read the full breastfeeding detail

Pregnancy & breastfeeding ratings are from Natural Medicines (Therapeutic Research Center) — the full detail is in the Special populations card below. Safety guidance is general; always confirm with your pharmacist or doctor for your situation.

Still wondering about combining Fluoxetine and Methionine? Ask Dr. Brian Staiger, PharmD, BCPS directly ›
What to actually watch for

No Interaction Found — But Data Suggests Methionine and Fluoxetine May Share Several of the Same Side Effects

This is not an interaction. Neither one changes how your body handles the other, and nothing here says they react together. What our sources do show is that each has separately been linked to the effects below — so taking both can make those effects more likely to turn up, and harder to pin on one or the other if they do. One of them is worth acting on rather than waiting out — marked below.

  • Liver problems Worth acting on Additional detail

    Methionine

    “A single dose of 8 grams of methionine has reportedly caused hepatic encephalopathy in patients with cirrhosis. Long-term use of methionine-containing parenteral nutrition solution has been linked to liver toxicity in infants.”

    Methionine · Natural Medicines adverse-effect record, reported in cirrhosis.

    2 sources cited
    1. 9340. Anon. Should methionine be added to paracetamol formulations? Drug Ther Perspect 1997;10:11-3. DOI
    2. 9338. Btaiche IF, Khalidi N. Parenteral nutrition-associated liver complications in children. Pharmacotherapy 2002;22:188-211.. PubMed

    Fluoxetine

    Listed in the ADVERSE REACTIONS section of the FDA label for Fluoxetine. Read the label on DailyMed ›

  • Mood changes or irritability / Drowsiness / Swelling / Dizziness / Headache Additional detail

    Methionine

    “Orally or intravenously, methionine can cause dizziness, drowsiness, headache, and irritability.

    A case of cerebral edema ultimately leading to death has been reported in a patient receiving methionine 100 mg/kg orally.”

    Methionine · Natural Medicines adverse-effect record, reported in cluster headache.

    4 sources cited
    1. 9339. 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
    2. 9340. Anon. Should methionine be added to paracetamol formulations? Drug Ther Perspect 1997;10:11-3. DOI
    3. 94095. 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
    4. 63119. 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

    Fluoxetine

    Listed in the ADVERSE REACTIONS section of the FDA label for Fluoxetine. Read the label on DailyMed ›

  • Low blood pressure Additional detail

    Methionine

    “Orally or intravenously, methionine can cause hypotension. High-dose methionine (75-100 mg/kg daily) may increase plasma concentrations of homocysteine, which is a risk factor for vascular disease. However, a study of patients with type 2 diabetes and a history of cardiovascular disease (CVD) showed that methionine loading did not increase homocysteine concentrations, and that a cause-effect relationship between incr…”

    Methionine · Natural Medicines adverse-effect record, reported in cardiovascular disease (cvd).

    6 sources cited
    1. 9339. 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
    2. 9340. Anon. Should methionine be added to paracetamol formulations? Drug Ther Perspect 1997;10:11-3. DOI
    3. 63112. 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
    4. 63114. 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
    5. 63115. 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
    6. 63110. 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

    Fluoxetine

    Listed in the ADVERSE REACTIONS section of the FDA label for Fluoxetine. Read the label on DailyMed ›

  • Vomiting Additional detail

    Methionine

    “Orally or intravenously, methionine can cause vomiting.”

    Methionine · Natural Medicines adverse-effect record, reported in nausea and vomiting.

    2 sources cited
    1. 9339. 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
    2. 9340. Anon. Should methionine be added to paracetamol formulations? Drug Ther Perspect 1997;10:11-3. DOI

    Fluoxetine

    Listed in the ADVERSE REACTIONS section of the FDA label for Fluoxetine. Read the label on DailyMed ›

Effects for Fluoxetine come from the ADVERSE REACTIONS section of its FDA label; effects for Methionine come from the Natural Medicines adverse-effect record, quoted above. Wording is matched across sources by our own clinical vocabulary, so treat this as a prompt to pay attention, not a diagnosis.

Special populations

Methionine in Pregnancy & Breastfeeding

Pregnancy And Lactation Likely Safe

When used orally in amounts commonly found in food. There is insufficient reliable information available about the safety of methionine in medical doses during pregnancy and lactation; avoid using.

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.© 2026 Therapeutic Research Center

From our Q&A

Questions About Methionine or Fluoxetine

These are real questions from readers, answered by the pharmacists at HelloPharmacist — written by a person, not generated from a database. Each one covers Methionine or Fluoxetine, not necessarily both, but if one is close to what you were about to ask it will usually go further than a database entry can:

Not quite your question? Ask our pharmacists directly — it is free, there is no account required, and answers usually come back within 24 hours.

Everything else you take

See Every Supplement That Interacts With Fluoxetine

This page covers Methionine only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Fluoxetine page lists 163 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), American Hellebore (major), Arsenic (major), Cesium (major) and Ephedra (major).

By severity: 8 major · 127 moderate · 28 minor.

From our pharmacist’s overview on the Fluoxetine page

“Grapefruit is the surprise at the top of fluoxetine's (Prozac) supplement list. In large amounts it can stretch the QT interval, the electrical pause between heartbeats, and fluoxetine, a widely prescribed antidepressant, can do the same, raising the odds of a dangerous rhythm.”

Reviewed by 2 · Jul 18, 2026

Open the Fluoxetine interaction page

One more smart check

Taking Methionine as Part of a Dietary Supplement Product? Check It for Interactions

We hold 3,129 real supplement products containing Methionine, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Methionine. Even though Methionine itself has no known interaction with Fluoxetine, another ingredient on your label might. Find your product and we’ll check every ingredient on its label:

How much people look this up

Where Methionine and Fluoxetine Sit Against Everything Else

Out of every supplement and medication people look up on HelloPharmacist, here is where these two land this week — and which way each has been moving.

Supplement Methionine
Top 5%

#61 of 1,452 supplements looked up here in the last 7 days

29 days ago today
Medication Fluoxetine
Top 1%

#28 of 2,830 medications looked up here in the last 7 days

29 days ago today

Position among everything looked up on this site, not a measure of how commonly either one is used or how important it is. A supplement can climb this list because of a news story. It counts every request to the page, automated ones included, and nothing here identifies anyone.

Where does our data come from?
  • Source: the Natural Medicines (TRC Healthcare) clinical database — the evidence-graded professional reference for herb & supplement interactions.
  • Citation library: 103,510 references behind our interaction content, 65,311 of them resolved to verified PubMed/DOI sources. See every Methionine reference on this page ↓
  • Freshness: we automatically re-check this combination every week — this pair was last verified September 13, 2026. The Methionine and Fluoxetine records this page draws on were last updated July 10, 2026.
  • What “no known interaction” means: no documented interaction in the sources above — not a guarantee of safety. Supplements are studied far less than prescription drugs, so we say exactly what the evidence supports, and nothing more.
Data structure & sourcing designed and verified by .
Supplement

About Methionine

What is Methionine?

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

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.

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

An interaction check asks whether these two react with each other — it does not ask whether Methionine is a good idea for someone in your situation. Here is what our Methionine record says about it on its own.

Methionine: dosing

There is no single standard supplement dose of methionine for general health, and most healthy people do not need extra beyond what they eat. Your body's daily methionine needs are normally met through a balanced diet.If a product is used, follow the directions on the label and do not take more than recommended.

From our Methionine monograph — the full record covers uses, side effects and every documented interaction.

Read the full Methionine monograph & all interactions
Medication

About Fluoxetine

What Is Fluoxetine Used For?

Brand names: Prozac, Sarafem

Fluoxetine is approved to treat four conditions: major depressive disorder (MDD), obsessive-compulsive disorder (OCD), bulimia nervosa (a binge-eating and purging disorder), and panic disorder — with or without agoraphobia (fear of situations that feel hard to escape).

It works for adults across all four conditions, and for children and teens with depression (ages 8–18) and OCD (ages 7–17).

See full Fluoxetine drug information
Keep checking

Other Drugs & Methionine

Browse every other medication we’ve checked against Methionine — both the ones with a known interaction and the ones without. Select any drug for the full detail.

0Major
0Moderate
0Minor
2,829No known interaction
2,829 No interaction
No interaction 2,829 drugs checked — show the list

We also checked Methionine against these medications and found no known interaction in our sources. Open any page to confirm.

Showing the 60 most looked-up of 2,829 medications checked with no known interaction — see the full Methionine list.

See the full Methionine interactions page
See every supplement checked against Fluoxetine, ranked by severity
Evidence & sources

Methionine References

The 12 references that drive our Methionine 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.

  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

Medication overviews come from MedlinePlus (NIH); supplement label data from the NIH Dietary Supplement Label Database. Content is written and reviewed by licensed HelloPharmacist pharmacists — see our data sources and editorial standards.

Pharmacist Counseling Corner

Taking Methionine and Fluoxetine Together: Common Questions

Is it safe to take Methionine with Fluoxetine?
We do not list a known interaction between Methionine and Fluoxetine. That does not guarantee the combination is risk-free, so confirm with your pharmacist or doctor — especially if you take other medications or have a health condition.
Do Methionine and Fluoxetine have any of the same side effects?
Yes — our sources link each of them separately to 8 of the same effects. That is not an interaction: neither changes how your body handles the other. It does mean that if one of those effects turns up, it can be harder to tell which one is behind it. They are listed on this page with the source behind each.
Does Fluoxetine interact with any supplements?
Yes. Fluoxetine has documented interactions with 163 supplements in our database — Methionine is not one of them. The Fluoxetine interaction page linked on this page lists every one, ranked by severity.

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

Where next

Keep Exploring

Methionine monograph Uses, safety profile, and every drug interaction in one place Fluoxetine drug information The full plain-English guide to this medication Fluoxetine supplement interactions Every supplement checked against Fluoxetine, ranked by severity Supplement interaction checker Check any supplement or product against your medications Browse medications A–Z Every drug we’ve checked against herbs & supplements References The 12 citations behind this page Ask a pharmacist Free, personal answer from our licensed team

Still Have a Question About Fluoxetine and Methionine?

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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.