α-Humulene is a sesquiterpene that has been found in C. sativa, C. indica, and hemp with diverse biological activities. It is lethal to A. subpictus, A. albopictus, and C. tritaeniorhynchus mosquito larvae (LC50s = 6.19, 7.39, and 12.05 mg/ml, respectively). α-Humulene reduces growth of MCF-7 breast cancer cells by approximately 50% when used at a concentration of 32 mg/ml. It also reduces viability of Caco-2 cells in a concentration-dependent manner (IC50 = 24.4 mg/ml) but has no effect on viability of rat hepatocytes. In vivo, α-humulene (50 mg/kg) reduces histamine-induced paw edema in mice as well as carrageenan-induced TNF-α and IL-1β production and paw edema in mice and rats. It also reduces carrageenan-induced production of prostaglandin E2 (PGE2) and expression of inducible nitric oxide synthase (iNOS) and COX-2 in rats.