The purpose of the study was to analyze the potential capacity of a dietary supplement , based on gamma linolenic acid , vitamin E , vitamin C , beta-carotene , coenzyme Q@ and Vitis Vitifera , to reduce side effects , in particular the dry skin , erythema and desquamation , due to treatment with oral isotretinoin , and evaluate the ability of the product to increase adherence to therapy in patients with acne .