Characteristics of heavy users of outpatient prescription drugs.

One hundred fifty-eight users of eight or more different prescription drugs in a three-month period were identified, using computerstored pharmacy data. Compared with 99 "light" users of only one or two different drugs, these heavy users were more likely to be older, female, and white and to have blue collar occupations, if male, or to be housewives, if female. Heavy drug use was associated with greater use of other medical care and was usually a persistent characteristic. Prepayment for drug prescriptions was not associated with heavy use. Among heavy users were found some severely ill individuals, and some with emotional problems that appear to contribute to symptoms and requests for drugs. In a 21-month period, adverse drug reactions were experienced by 28% of heavy users as compared with 8% of light users.