What it is
Setmelanotide is a peptide that activates the MC4 receptor in the brain, a key switch that controls hunger and fullness.
In certain rare genetic conditions, the signals that should reach this receptor are broken, causing intense hunger from early childhood. Setmelanotide helps restore that signal.
US regulatory status
FDA-approved (Imcivree) for obesity due to specific rare genetic causes (POMC, PCSK1 or LEPR deficiency confirmed by testing), for Bardet-Biedl syndrome, and since March 2026 for acquired hypothalamic obesity in people 4 and older. It is not approved for common obesity.
What the research shows
Phase 3 trials in people with these rare conditions showed meaningful weight loss and less hunger. It was not effective enough to be developed for general obesity.
How it is given
Daily subcutaneous injection (vial)
Commonly reported side effects
- Skin darkening (hyperpigmentation)
- Injection site reactions
- Nausea
- Headache
- Diarrhea or stomach pain
- Spontaneous erections in males
Questions to ask your provider
- Should I or my child have genetic testing for obesity?
- How will we check for mood changes while on setmelanotide?
- What skin changes should I expect?