Int J Dermatol. 2009 May; 48(5): 498-505Yahya HBACKGROUND: Community-based studies of acne vulgaris conducted in many parts of the world show that it is very common in adolescents but little is known from Africa. METHODS: In a cross-sectional study, 539 randomly selected students aged 11-19 years in a secondary school in Kaduna, Nigeria were administered a questionnaire to assess self-report of acne, its severity and impact; beliefs and perceptions of causes, and treatments used. 418 students were later examined to detect and grade acne severity. RESULTS: 274 (50.8%) were male while 265 (49.2%) were female. Mean age for respondents was 16 years. 320 students (59.4%) self-reported acne. Of 418 students examined, 379 had acne giving a prevalence of 90.7%. There was no significant gender difference in prevalence at all ages of adolescence. Prevalence of acne increased with age (76.7% at age 10-13 years; 88.2% at age 14-16 years; 97.1% at age 17-19 years). 353 of 379 (93.1%) had mild acne while 26 of 379 (6.9%) had moderate acne. The severity of acne was similar in boys and girls. 47.7% of students reported feeling "very sad/unhappy" about their acne although in more than 70% of those who self-reported, this did not interfere with relationship with family, friends or school work. Diet was the commonest factor believed to cause acne. Cleansing agents were the most commonly used treatments. CONCLUSIONS: Acne vulgaris is very common in Nigerian adolescents, although it is mild acne in most.