The abuse of prescription and over-the-counter psychoactive medications, tobacco, caffeine or alcohol (ethanol) by elderly adults is a clinical situation that many physicians encounter. The issues of diagnosis and clinical presentation of drug abuse may differ in the elderly compared with younger individuals, and physicians need to be aware of these issues to ensure the most appropriate management of elderly patients.Cognitive (e.g. memory loss), physical (e.g. falls) and behavioural (e.g. depression, insomnia) changes may be signs of substance abuse in elderly individuals. However, these signs may be misdiagnosed as being due to aging. The quantity of the substance(s) used by elderly persons may underestimate the frequency and severity of problems as, due to altered pharmacokinetics and pharmacodynamics, the elderly are more sensitive to the effects of many drugs.Hypnosedatives are among the most commonly used psychotropic medications in the elderly and they have a high potential for abuse. The elderly are very sensitive to the CNS depressant effects of these drugs and, as a result, misuse (e.g. unintentional overuse) can lead to dependence and abuse. There is limited information on the abuse of opioid analgesics, but their misuse can result in physical dependence.Although the prevalence of tobacco smoking is relatively low among the elderly, older smokers tend to smoke more and be more dependent on nicotine than their younger counterparts. Quitting smoking in old age has significant health benefits, and increased age has been found to be associated with an increased success in achieving abstinence.Caffeine, consumed mainly in the form of tea, may contribute to insomnia and complaints about sleep quality, especially among the institutionalised elderly. Ulcers, pancreatic cancer and osteoporosis have been related to caffeine intake in some, but not all, studies.Alcohol abuse, dependence and associated problems are less likely to be detected in the elderly because many of the diagnostic criteria (e.g. work-related problems) do not apply. Elderly patients in acute alcohol withdrawal may require more careful management than younger ones.Prevention strategies for substance abuse range from the education of patients, physicians and other healthcare workers to monitoring, regulations and legislations by governments. Future research should aim to improve the diagnosis and detection of substance abuse, and to develop treatment and prevention programmes.