Weight-loss drugs can be anti-inflammatory for certain conditions.

Maria Bugeja

Verdict True but lacks context

Semaglutide and tirzepatide lower markers of inflammation in the blood, and part of that effect appears to come from the drugs rather than the weight loss alone. Whether that helps treat specific inflammatory diseases is still being studied; the drugs are not approved as anti-inflammatory treatments.How we reached this verdict ↓

Analysis and evaluation

Semaglutide and tirzepatide lower inflammation in the body, and the effect is not only a side effect of weight loss. Whether that makes them a treatment for inflammatory diseases is not yet established.

The drugs lower markers of inflammation

Long-running, low-level inflammation is common in obesity. Researchers track it through markers in the blood, chiefly C-reactive protein (CRP). Analyses of the STEP 1, 2 and 3 trials found large falls in CRP on semaglutide compared with a placebo, and a 2024 meta-analysis confirmed the effect across studies. A 2025 meta-analysis found the same for tirzepatide.

Part of the effect comes from the drug itself

Losing body fat lowers inflammation on its own, so some of the fall is expected from weight loss alone. But in the SELECT trial of semaglutide, CRP began falling before much weight had been lost, and it fell even in some participants who lost no weight. That points to an anti-inflammatory effect beyond weight loss.

Effects on inflammatory diseases are still being tested

Researchers are studying whether this helps people with conditions such as some forms of arthritis, inflammatory bowel disease and psoriasis. A 2026 systematic review of immune-mediated inflammatory diseases describes early, mostly observational evidence.

The strongest trial result is STEP 9, in which people with obesity and knee osteoarthritis had less knee pain on semaglutide than on a placebo. But losing weight also takes pressure off the knees, so the trial cannot show the improvement came from an anti-inflammatory effect.

Evaluation

The anti-inflammatory effect is real and well documented, and some of it appears to come from the drugs themselves. Their use against specific inflammatory conditions is still being investigated, and they are not approved for that purpose.

Editorial note

How we assessed this claim

We split the claim in two: whether these medicines reduce inflammation, and whether that translates into improvement in inflammatory conditions. We gave most weight to large trials and to reviews pooling several studies.

The first part is well supported, so the claim cannot fall below True but lacks context. It stops short of True because "for certain conditions" goes further than the evidence: trials show lower inflammation markers, not yet a proven treatment for a named inflammatory disease.

Limitations

"Weight-loss drugs" is a broad term. The evidence here concerns semaglutide and tirzepatide and should not be read across to every medicine used for weight loss.
Showing that a drug lowers a marker of inflammation is not the same as showing it treats an inflammatory disease.
The STEP and SELECT trials were funded by Novo Nordisk, which makes semaglutide.