The mitochondrial respiratory chain (MRC) and ATP synthase (complex V) play an essential role in cellular energy production by the process of oxidative phosphorylation. In addition to inborn errors of metabolism, as well as secondary causes from disease pathophysiology, an impairment of oxidative phosphorylation can result from drug toxicity. These 'off-target' pharmacological effects can occur from a direct inhibition of MRC enzyme activity, an induction of mitochondrial oxidative stress, an uncoupling of oxidative phosphorylation, an impairment of mitochondrial membrane structure or a disruption in the replication of mitochondrial DNA. The purpose of this review is to focus on the off-target mitochondrial toxicity associated with both commonly used pharmacotherapies and a topical 'weight loss' agent. The mechanisms of drug-induced mitochondrial impairment will be discussed together with putative therapeutic strategies to counteract the adverse effects of the pharmacotherapy.