Low endogenous levels of dehydroepiandrosterone (DHEA) and/or its sulfoconjugated derivative DHEA-S have been associated with diseases such as lupus, cancer, and diabetes. Circulating concentrations of DHEA and DHEA-S resulting from endogenous production or hormone supplementation may also be relevant in psychiatric illness. Drugs may significantly increase or decrease circulating concentrations of these adrenal androgens by various mechanisms. Some agents, such as dexamethasone, affect the HPA axis by inhibiting ACTH and therefore decrease DHEA and DHEA-S concentrations. Central nervous system agents, including carbamazepine and phenytoin, induce the P450 enzymes that metabolize DHEA and DHEA-S and therefore decrease circulating concentrations of these hormones. Danazol alters the ratio between DHEA and DHEA-S by inhibiting sulfatase. As research moves forward to better understand the relationships of these adrenal androgens with health and disease, it is essential that studies be designed to control for the influence of administered pharmaceuticals on DHEA and DHEA-S.