Adverse reactions to drugs in general practice.

Of 817 patients in a general-practice survey of adverse reactions to drugs, 41% were thought to have "certainly" or "probably" had a reaction to the drug prescribed. Adverse effects on the gastrointestinal and central nervous systems were the most frequently reported, and 90% of reactions had occurred by the fourth day of treatment. More patients given drugs acting on the central nervous system and antihistamines reported reactions than those in other categories. A higher incidence of adverse drug effects is shown in this general-practice survey than in other, mainly hospital-based, surveys. Further intensive surveillance for adverse effects of drugs is recommended to provide additional information on the burden of drug-induced disease in the community.