[Use and sources of medicines: a population-based study in Campinas, São Paulo State, Brazil].

The use of medicines is influenced by different factors. This study aimed to analyze the use of medicines and identify the sources for obtaining them and associated factors, using a population-based cross-sectional design with two-stage cluster sampling in Campinas, São Paulo State, Brazil, in 2008. Prevalence of use of at least one drug in the 3 previous days was 57.2% and prevalence of obtaining the drug from the Brazilian Unified National Health System (SUS) was 30%. 47.8% of individuals with no health insurance had to pay out-of-pocket for their medication, and 10.9% of individuals with insurance nevertheless obtained their medication from the SUS. Use of medicines obtained from the SUS was associated with older age, widowhood, black or brown skin color, lower schooling and income, and lack of insurance. Only 2.1% reported not being able to obtain the prescribed medication, and the main reasons were lack of availability in the public system and lack of money for out-of-pocket purchases. The study identified the subgroups that obtained most of their medicines in the SUS and showed that these were the subgroups with the lowest use of medicines in the system.