cis-6-Hexadecenoic acid is a monounsaturated fatty acid and is one of the primary fatty acids in human skin. cis-6-Hexadecenoic acid levels are increased in isolated sebum from the face and back of patients with acne. In contrast, levels are decreased in the non-lesional skin and isolated sebum of atopic dermatitis patients, which correlates with an increase in S. aureus in the sebum. It is active against S. aureus in vitro when used at a concentration of 5 µg/ml at pH 5.5. cis-6-Hexadecenoic acid disrupts membrane integrity, the proton motive force, increases membrane fluidity, and inhibits the electron transport chain in S. aureus.