Drug & supplement interaction

Methylsulfonylmethane (msm) + 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 Methylsulfonylmethane (msm) 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

Methylsulfonylmethane (msm) 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 Methylsulfonylmethane (msm) 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 Methylsulfonylmethane (msm) 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.

Methylsulfonylmethane (msm) safety at a glance

Methylsulfonylmeth... overall Use caution Generally well tolerated short-term, but long-term safety is not well studied.
Pregnancy Avoid Not enough safety data, so it is best avoided during pregnancy.
Breastfeeding Avoid There is no reliable safety information for breastfeeding, so avoid it.

Safety guidance is general; always confirm with your pharmacist or doctor for your situation.

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

No Interaction Found — But Data Suggests Methylsulfonylmethane (msm) 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.

  • Bloating or gas / Stomach upset / Diarrhea / Nausea Additional detail

    Methylsulfonylmethane (msm)

    “Orally, MSM may cause mild gastrointestinal discomfort, nausea, bloating, and diarrhea.”

    Methylsulfonylmethane (msm) · Natural Medicines adverse-effect record, reported in diarrhea.

    2 sources cited
    1. 8574. Barrager E, Veltmann JR Jr, Schauss AG, Schiller RN. A multicentered, open-label trial on the safety and efficacy of methylsulfonylmethane in the treatment of seasonal allergic rhinitis. J Altern Complement Med 2002;8:167-73. PubMed
    2. 12469. Usha PR, Naidu MU. Randomised, Double-Blind, Parallel, Placebo-Controlled Study of Oral Glucosamine, Methylsulfonylmethane and their Combination in Osteoarthritis. Clin Drug Investig. 2004;24(6):353-63. PubMed

    Fluoxetine

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

  • Trouble sleeping / Tiredness / Headache Additional detail

    Methylsulfonylmethane (msm)

    “Orally, MSM may cause headache, fatigue, insomnia, and difficulty concentrating.”

    Methylsulfonylmethane (msm) · Natural Medicines adverse-effect record, reported in cluster headache.

    2 sources cited
    1. 8574. Barrager E, Veltmann JR Jr, Schauss AG, Schiller RN. A multicentered, open-label trial on the safety and efficacy of methylsulfonylmethane in the treatment of seasonal allergic rhinitis. J Altern Complement Med 2002;8:167-73. PubMed
    2. 14335. Kim LS, Axelrod LJ, Howard P, et al. Efficacy of methylsulfonylmethane (MSM) in osteoarthritis pain of the knee: a pilot clinical trial. Osteoarthritis Cartilage 2006;14:286-94. PubMed

    Fluoxetine

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

  • Itching Additional detail

    Methylsulfonylmethane (msm)

    “In rare cases, MSM has caused pruritus when taken orally.”

    Methylsulfonylmethane (msm) · Natural Medicines adverse-effect record, reported in pruritus.

    1 source cited
    1. 8574. Barrager E, Veltmann JR Jr, Schauss AG, Schiller RN. A multicentered, open-label trial on the safety and efficacy of methylsulfonylmethane in the treatment of seasonal allergic rhinitis. J Altern Complement Med 2002;8:167-73. PubMed

    Fluoxetine

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

Reported for Methylsulfonylmethane (msm) but not commonly for Fluoxetine: trouble concentrating.

Effects for Fluoxetine come from the ADVERSE REACTIONS section of its FDA label; effects for Methylsulfonylmethane (msm) 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.

From our Q&A

Questions About Methylsulfonylmethane (msm) 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 Methylsulfonylmethane (msm) 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 Methylsulfonylmethane (msm) 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

How much people look this up

Where Methylsulfonylmethane (msm) 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 Methylsulfonylmethane (msm)
Top half

#699 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 Methylsulfonylmethane (msm) reference on this page ↓
  • Freshness: we automatically re-check this combination every week — this pair was last verified September 13, 2026. The Methylsulfonylmethane (msm) 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 Methylsulfonylmethane (msm)

What is Methylsulfonylmethane (msm)?

  • Osteoarthritis and joint pain
  • Muscle soreness after exercise
  • Inflammation
  • Skin and hair health
  • Allergy symptoms

Methylsulfonylmethane (MSM) is a natural sulfur compound that people most often take for joint pain and exercise recovery. Some early research suggests it may modestly help osteoarthritis symptoms, but the evidence is limited and more study is needed. It appears generally well tolerated in the short term, but talk with your pharmacist or doctor before starting it.

Not applicable (a sulfur-containing compound) · Capsules, tablets, powders, creams, and combination joint supplements

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

Methylsulfonylmethane (msm): dosing

There is no official or standardized dose of MSM. Studies have used a wide range of amounts, and the best dose is not clearly established.The safest approach is to follow the directions on the product label and not take more than recommended. They can help you decide if it is appropriate and what amount is reasonable.

From our Methylsulfonylmethane (msm) monograph — the full record covers uses, side effects and every documented interaction.

Read the full Methylsulfonylmethane (msm) 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 & Methylsulfonylmethane (msm)

Browse every other medication we’ve checked against Methylsulfonylmethane (msm) — 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 Methylsulfonylmethane (msm) 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 Methylsulfonylmethane (msm) list.

See the full Methylsulfonylmethane (msm) interactions page
See every supplement checked against Fluoxetine, ranked by severity
Evidence & sources

Methylsulfonylmethane (msm) References

The 4 references that drive our Methylsulfonylmethane (msm) 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. Barrager E, Veltmann JR Jr, Schauss AG, Schiller RN. A multicentered, open-label trial on the safety and efficacy of methylsulfonylmethane in the treatment of seasonal allergic rhinitis. J Altern Complement Med 2002;8:167-73. PubMed
  2. Usha PR, Naidu MU. Randomised, Double-Blind, Parallel, Placebo-Controlled Study of Oral Glucosamine, Methylsulfonylmethane and their Combination in Osteoarthritis. Clin Drug Investig. 2004;24(6):353-63. PubMed
  3. Kim LS, Axelrod LJ, Howard P, et al. Efficacy of methylsulfonylmethane (MSM) in osteoarthritis pain of the knee: a pilot clinical trial. Osteoarthritis Cartilage 2006;14:286-94. PubMed
  4. Hwang JC, Khine KT, Lee JC, Boyer DS, Francis BA. Methyl-sulfonyl-methane (MSM)-induced acute angle closure. J Glaucoma. 2015 Apr-May;24(4):e28-30. 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 Methylsulfonylmethane (msm) and Fluoxetine Together: Common Questions

Is it safe to take Methylsulfonylmethane (msm) with Fluoxetine?
We do not list a known interaction between Methylsulfonylmethane (msm) 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 Methylsulfonylmethane (msm) 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 — Methylsulfonylmethane (msm) 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

Methylsulfonylmethane (msm) 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 4 citations behind this page Ask a pharmacist Free, personal answer from our licensed team

Still Have a Question About Fluoxetine and Methylsulfonylmethane (msm)?

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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.