The drug classes used to treat the major psychiatric disorders--antidepressants, antimanic agents, antipanic drugs, and neuroleptics--all produce side effects that may affect work performance. An understanding of the pharmacology of psychotropic drugs will enable the clinician to recognize the most common adverse effects of these drugs on performance. For example, tertiary amine tricyclic antidepressants and benzodiazepines may decrease alertness. The slowed visual accommodation produced by amine tricyclics or low-potency neuroleptics may adversely affect fine-motor control. Likewise, various psychotropic drugs, including neuroleptics and lithium (at toxic levels), may cause motor incoordination. However, the clinician should bear in mind that failure to provide treatment for psychiatric disorders is far more disruptive than are any side effects of such treatment.