Adverse drug reactions are among the most common adverse events and a significant cause of preventable morbidity and mortality. As multimorbidity and
polypharmacy are frequent in this population, the elderly are at special risk for
adverse drug events, although the calendar age has not been proved as independent risk factor in this context. In particular falls and
delirium are clinically significant and typical
adverse drug events in the elderly. In this review mechanisms and factors which determine adverse drug re actions are described, and possible strategies for an effective prevention are given. This covers pharmacokinetic, pharmacogenetic and pharmacodynamic aspects as well as factors influencing individual adherence to
drug therapy. A significant portion of
adverse drug reaction may be prevented by a thorough indication and prudent monitoring of
pharmacotherapy. Also adherence to
pharmacotherapy may be improved by tailored and individual means referring to the patient's needs and expectancies. In the elderly functional limitations such as reduced cognitive abilities, reduced visual acuity and impaired dexterity determine an ineffective
pharmacotherapy and
medication errors. Hereby these functional limitations are significant predictors of
adverse drug events in the context of self-management of
pharmacotherapy. Testing of functional abilities as provided in the geriatric assessment is helpful to identify these factors. Among altered pharmacokinetic factors in the elderly, reduced renal function is most important to avoid overdosage. Although a precise measurement of renal function is not possible in a bed-side manner, an estimation of actual renal function utilizing estimation-formulas should always take place.