Effect of Evening Primrose Oil Supplementation on Selected Parameters of Skin Condition in a Group of Patients Treated with Isotretinoin—A Randomized Double-Blind Trial

Background: Retinoids, which include isotretinoin, reduce sebum levels, the degree of epidermal wetness (CORN) and cause an increase in transepidermal water loss (TEWL). Weight gain has also been observed in isotretinoin-treated patients. An agent that can reduce the severity of isotretinoin side effects is evening primrose oil (Oenothera paradoxa). The purpose of this study was to evaluate the effect of evening primrose oil supplementation in patients with acne vulgaris treated with isotretinoin on skin hydration status (CORN), transepidermal water loss (TEWL), skin oiliness (sebum) and changes in body weight and BMI. Methods: Patients diagnosed with acne were assigned to the isotretinoin-treated group (n = 25) or the isotretinoin and evening primrose oil-treated group (n = 25). The intervention lasted 9 months. CORN (with a corneometer), TEWL (with a tewameter) and sebum (with a sebumeter) were assessed twice, as well as body weight and BMI (Tanita MC-780). Results: The isotretinoin-treated group showed statistically significant reductions in CORN (p = 0.015), TEWL (p = 0.004) and sebum (p < 0.001) after the intervention. In the group treated with isotretinoin and evening primrose oil, TEWL and sebum levels also decreased significantly (p < 0.05), while CORN levels increased from 42.0 ± 9.70 to 50.9 ± 10.4 (p = 0.017). A significant decrease in body weight (p < 0.001) and BMI (p < 0.001) was observed in both groups after 9 months of intervention. Conclusions: During isotretinoin treatment, supplementation with evening primrose oil increased skin hydration. However, there were no differences between groups in transepidermal water loss, skin oiliness, weight loss and BMI.