Pharmacy customers' knowledge of side effects of purchased medicines in Mexico

To analyse pharmacy customers' knowledge and information sources about side effects of medicines they purchased and factors associated with this knowledge.

Cross-sectional survey and semi-structured interviews with customers of 52 randomly selected community pharmacies in Morelos state, Mexico. Customers were included if they were older than 18 years, bought at least one drug either with or without medical prescription, and agreed to take part in the survey. Data were analysed using a multinomial logistic regression model.

A total of 1445 customers buying 1946 drugs were surveyed (age 42.9 +/- 15.7 years, 56.9% female); 627 (59%) of 1055 customers who purchased prescription-only medicines (POM) did so without a prescription. Of all customers interviewed, 172 (11.9%) affirmed that the bought medicine(s) could cause harm. Only half of those (87 or 6%) were able to identify correctly at least one side effect of the purchased medicines. The majority received the information about side effects from a physician. Customers in semirural areas knew less about side effects (odds ratio: 0.26; 95% CI: 0.11-0.61; P = 0.00); whereas customers buying medicines for chronic pain, hypertension or diabetes knew more (odds ratio 2.63; 95% CI: 1.44-4.80; P = 0.00).

The overall majority of customers did not know that medicines they bought could be harmful. This is particularly alarming because they frequently used POM without consulting a physician.