Objective: Prediction of complexion changes in useres of triphasic oral contraceptive containing norgestimate. Design: Analysis of data from a prospective multicentre open study. Setting: Department of Obstetrics and Gynaecology, Charles University, Prague. Methods: Acne severity was evaluated in users of a triphasic norgestimate-containing contracepti- ve within a six month period. Based on subjective evaluation of acne, three subgroups of patients were selected: A) users where acne improved or disappeared; B) users in whom acne deteriora- ted, C) users who newly developed acne. Differences between group A and the other groups were established in the proportion or distribution of parameters related to the etiology of acne: age, weight, weight changes during the study, presence of hirsutism, presence of a regular menstrual cycle prior to the start of hormonal contraception use, and smoking. Results: The effect of the pill use on acne was assessed in a total of 3,990 women. Out of 1,201 women with acne before the start of the study, improvement or disappearance of acne during the study was reported by 940 users (subgroup A) (78.27%). In 221 women (18.40%), the extent of acne remained unaltered whereas it increased (subgroup B) in only 30 women (2.50%). Acne newly developed during the study in 49 women (subgroup C), i.e., in 1.2% of the whole group. Users showing deterioration of acne (subgroup B) were found to have hirsutism less frequently. The subgroup even showed a decrease in mean weight during the study. Users with newly developed acne were - compared with subgroup A - significantly older, had a lower weight at the start of the study, and showed a higher frequency of regular menstrual cycles prior to starting hormonal contraception. The differences in the incidence of clinical parameters in the subgroups reached only borderline statistical significance and, hence, are not relevant. Conclusion: An extensive multicentric study confirmed the beneficial effect of a triphasic norges- timate-containing contraceptive on complexion. The presence of clinical parameters related to the etiology of acne does not allow to predict the individual response of the skin to hormonal therapy.

        Key words: acne, hormonal therapy, norgestimate, hormonal contraception, weight, smoking, menstrual cycle