The incidence of adverse reactions to drugs is two or three times greater in elderly people than in adults. Elderly people are great consumers of psychotropic drugs which are most often responsible for these reactions, the chief culprits being anticholinergics and neuroleptics. These drugs must be avoided at that age, but neuroleptics may be justified in some circumstances, such as uncontrollable excitement or delusions. The dysautonomia associated with ageing induces functional disorders that are similar to those induced by psychotropic drugs, so that the responsibility of these drugs is frequently under-evaluated. In those rare cases where psychotropic agents are mandatory, only one of them must be prescribed in low doses and, whenever possible, for a limited period.