Does semaglutide help knee arthritis pain?
Yes, in a specific group. A 68-week randomized trial found substantially greater weight loss and greater knee-pain improvement with semaglutide than placebo in adults who had both obesity and moderate knee osteoarthritis.
- Trial
- STEP 9, randomized and double-blind, at 61 sites in 11 countries
- Participants
- 407 adults; average age 56; 81.6% women; average BMI 40.3
- Pain result
- WOMAC pain changed by −41.7 points with semaglutide versus −27.5 with placebo
- Weight result
- −13.7% with semaglutide versus −3.2% with placebo
Why this result matters
Knee osteoarthritis is often treated as if the joint exists apart from the rest of the body. STEP 9 tested a different route: reduce obesity, a major mechanical and metabolic driver, and measure whether pain and function improve. They did.
What the trial does not prove
- It does not show that semaglutide regrows cartilage.
- It does not establish benefit for people without obesity.
- It does not prove the effect was independent of weight loss.
- It does not make semaglutide an FDA-approved arthritis-pain drug.
Safety and practical limits
Adverse events led 6.7% of semaglutide participants and 3.0% of placebo participants to stop the assigned treatment permanently. Gastrointestinal problems were the most common reason. The study was funded by Novo Nordisk, the manufacturer; that conflict does not erase the randomized result, but it belongs in the record.
Our verdict: For an older adult with obesity and painful knee osteoarthritis, this is one of the strongest peptide-related human results available. It supports a conversation about approved obesity care and joint load—not a claim that a peptide directly rebuilt the knee.
Primary source
- Bliddal H, et al. Once-Weekly Semaglutide in Persons with Obesity and Knee Osteoarthritis. New England Journal of Medicine, 2024. PMID 39476339.
Last reviewed August 11, 2026. Do not start or change a prescription based on this summary.