Serotonin (5-hydroxytryptamine [5-HT]) receptors regulate feelings of satiety and food intake.1 The serotonergic antiobesity compounds fenfluramine and dexfenfluramine were effective in causing weight loss but were associated with valvular heart disease, especially aortic and mitral valve insufficiency.2–5 These compounds were nonselective, affecting serotonin transporters as well as multiple serotonin receptor subtypes.6–8 Subsequent research and clinical observations implicated activation of the 5-HT2B receptor subtype as the cause of serotonergic valvulopathy.7,9–11 The 5-HT2B receptors are expressed on cardiac valvular interstitial cells and when stimulated produce a characteristic valvulopathy that is also observed with the nonselective dopamine agonists pergolide and cabergoline.12