In pharmacology, pleiotropy includes all of a drug's actions other than those for which the agent was specifically developed.^[1] It may include adverse effects which are detrimental ones,^[1] but is often used to denote additional beneficial effects.^[2]

For example, statins are HMG-CoA reductase inhibitors that primarily act by decreasing cholesterol synthesis, but which are believed to have other beneficial effects, including acting as antioxidants and stabilizing atherosclerotic plaques.^[1] Steroid drugs, such as prednisone and prednisolone, have pleiotropic effects, including systemic ones, for the same reason that endogenous steroid hormones do: cells throughout the body have receptors that can respond to them, because the endogenous ones are endocrine messengers.