A significant portion of the older population, which has increased due to the extension of life expectancy, takes various medications to treat diseases. As the number of drugs taken increases, the risk of adverse drug reactions increases, which are mostly caused by interactions between drugs. In addition, older people are more vulnerable to adverse drug reactions compared to younger people, due to various physiological changes due to aging and multiple co-morbidities. Adverse drug reactions that occur in geriatric patients can result in unexpected emergency room visits, prolong hospitalization, and in extreme cases, lead to death. In addition, individual’s health-related quality of life decreases and medical costs increase, which also increases the social cost burden. However, most adverse drug reactions can be predicted or prevented. Accordingly, the first half of this study looked at the characteristics of adverse drug reactions in the older adults, and the second half discussed preventive measures such as risk management of medications, sharing of prescription information, and role of community pharmacists and consumers.