To evaluate factors affecting the prevalence of dysmenorrhea in a group of Mexican students.A questionnaire was administered to 1152 high school students and the obtained data about severity, symptoms, and medications used were analyzed.Dysmenorrhea had a prevalence of 48.4% and was the cause of school absences for 24% of the affected students. It was mild in 32.9%, moderate in 49.7%, and severe in 17.4% of these students, of whom 28% consulted a physician and 60.9% self-medicated. The most common over-the-counter drugs used were a combination of paracetamol, pamabrom and pyrilamine maleate; metamizol (a nonsteroidal anti-inflammatory drug) plus butylhioscine; and naproxen. We found a significant correlation between the presence of dysmenorrhea and smoking, cycle pattern, cycle duration, flow duration, and amount of flow.The prevalence of dysmenorrhea was high in our sample. The condition caused short-term school absences and the students commonly addressed it by self-medicating.