The term lifestyle drug is imprecise, commonly applied to medications that treat non-lifethreatening illnesses or perceived deficiencies in physical, mental, or emotional states of normal human beings. Promoting and using medications for lifestyle enhancement involves a difficult balance between medical definitions of what constitutes a disease and consumers’ beliefs of what they want in the way of optimal functioning and well-being. The development, promotion, and use of lifestyle drugs has increased considerably since the 1990s, producing regulatory, financial, and ethical concerns.