Given the possibility of adverse side-effects, interactions with medicines and poisoning by contaminants among herbal medicine consumers (HM), we aimed to describe the consumption of HM by health centre users being treated with medicines.Cross-sectional, observational study.Setting. Thirteen health centres in the Community of Valencia.Users of either sex, over 14, chosen for a study of use of medicines to find differences between the sexes.The study variables, age, gender, education, consumption of medicines and use of HM, were gathered from the clinical records, the long-treatment card and an ad hoc structured survey. 801 out of 812 users took medicines. 159 took HM (19.6%; 95% CI, 16.9-22.3); average age 55.8 (SD, 16.5); women 58.5% (95% CI, 50.8-66.1). They took 226 HM (mean of 1.42; 95% CI, 1.32-1.52). Men consumed more HM (p > by 36.7% (95% CI, 30.4-43.0); stomach problems, 19.5% (95% CI, 14.3-24.6); nerves/depression, 12.8% (95% CI, 8.5-17.2); intestinal disorders, 10.6% (95% CI, 6.6-14.6); insomnia 5.8% (95% CI, 3.1-9.6). 49.1% (95% CI, 42.6-52.6) were manufactured HM.One of every five patients being treated with medicines is also taking HM by self-medication. The health authorities and doctors should advise of the risks to health and of the counter-indications of these products.