Adverse effect · Setmelanotide

How common is adverse effects with Setmelanotide?

B
Grade B — probable, not settledSame trials · effect size: moderate · adverse
Short answerProbable, not settled. Human data exist (Same trials) and mostly agree, showing a moderate effect — but too few, too small, or not yet peer-reviewed for a firm answer. Injection-site reactions and skin darkening in every participant, nausea and vomiting in a third to a half; hyperpigmentation is the MC1-receptor effect the drug cannot avoid.

What the studies show

Injection-site reactions and skin darkening in every participant, nausea and vomiting in a third to a half; hyperpigmentation is the MC1-receptor effect the drug cannot avoid.

“The most common adverse events were injection site reaction and hyperpigmentation, which were reported in all ten participants in the POMC trial; nausea was reported in five participants and vomiting in three participants.”

Verbatim, from the abstractClément K, van den Akker E, Argente J, et al. Efficacy and safety of setmelanotide, an MC4R agonist, in individuals with severe obesity due to LEPR or POMC deficiency: single-arm, open-label, multicentre, phase 3 trials. Lancet Diabetes Endocrinol, 2020

Human trials exist and mostly agree, but there are too few of them, they are too small, or one big one is still reading out. Expect the grade to move.

  1. 1

In context

Setmelanotide is a cyclic analogue of α-MSH that activates the MC4 receptor, the brain's main satiety switch. In people whose obesity is caused by rare mutations upstream of that receptor — POMC, PCSK1 or LEPR deficiency, or Bardet-Biedl syndrome — it restores the signal: 80% of POMC-deficient and 45% of LEPR-deficient patients lost at least a tenth of their body weight in a year, with hunger scores falling by a quarter to a half. Those trials had ten and eleven participants. In obesity that follows damage to the hypothalamus, a 120-person randomised trial found BMI fell 16.5% against a 3.3% rise on placebo; Canada approved that use in September 2026. It has no role in common obesity.

Setmelanotide is approved (rx) — rare genetic obesity; hypothalamic obesity in canada. Legal status differs by country — see the regulation section or the jurisdiction pages.

Questions

Is Setmelanotide proven to cause adverse effects?
Not yet settled. Same trials — LYO grades it B, meaning probable but liable to change as trials read out.
What studies are behind the grade?
Injection-site reactions and skin darkening in every participant, nausea and vomiting in a third to a half; hyperpigmentation is the MC1-receptor effect the drug cannot avoid.
Is Setmelanotide approved for this?
Setmelanotide is an approved medicine (Approved (Rx) — rare genetic obesity; hypothalamic obesity in Canada); whether this particular outcome is a licensed indication is stated on the compound page's regulation section.

Other outcomes for Setmelanotide

Written and maintained by LYO Research — how pages are written and checked. Reviewed 7 October 2026. Grades count human evidence only; see how LYO grades. Not medical advice. Correct this page →