What is MSM and does it help arthritis?
MSM is an organic sulfur compound (methylsulfonylmethane). Small trials at1,500–3,000 mg/day show modest reductions in knee osteoarthritis pain and stiffness over 12 weeks. It is well tolerated and often combined with glucosamine sulfate. Evidence is weaker than for curcumin or glucosamine alone.
What is MSM?
MSM stands for methylsulfonylmethane. It's a natural organic sulfur compound found in small amounts in plants, animals and humans. Sulfur is a building block for collagen and the cartilage that lines our joints.
As a supplement, MSM is sold for joint pain, stiffness, inflammation, exercise recovery, allergies and skin health. In the UK it usually appears either on its own or stacked with glucosamine and chondroitin.
What the evidence says
- Kim 2006 — 3,000 mg MSM twice daily for 12 weeks improved knee OA pain and physical function vs placebo.
- Debbi 2011 — 1.125 g MSM three times daily for 12 weeks reduced pain and improved knee OA function vs placebo.
- 2017 systematic review (Brien et al.) — MSM produced statistically significant but small improvements in pain and function for knee OA.
- Combined with glucosamine — several trials suggest the combination outperforms either ingredient alone for moderate OA pain.
- NICE NG226 does not currently recommend MSM on the UK healthcare system.
The honest summary: real but modest effect, decent safety profile, and best used as a 12-week trial alongside exercise and weight management — not as a replacement for them.
Dosage and how to take it
- Typical dose: 1,500–3,000 mg per day.
- Split: two or three doses, taken with food.
- Form: capsule, tablet or unflavoured powder dissolved in water.
- Trial length: 8–12 weeks before judging the effect.
- Stack: commonly combined with 1,500 mg glucosamine sulfate.
Side effects and safety
MSM is one of the better-tolerated joint supplements. Mild side effects can include:
- Bloating, mild diarrhoea or nausea
- Headache
- Skin rash or itching
- Insomnia if taken late in the day
Take care if you
- Are pregnant or breastfeeding — not enough safety data, avoid
- Take blood thinners (warfarin, apixaban) — speak to your GP first
- Have liver or kidney disease
Always tell your GP or pharmacist about any supplement, especially before surgery or if you start a new prescription medicine.
Frequently asked questions
Compare MSM to other joint supplements
MSM is one of many options. See where it fits next to glucosamine, plus what we recommend for the underlying condition.
Glucosamine guideOsteoarthritisAnti-inflammatory diet