Yes, Retinol Serum can be combined with other skin care products. However, it is important to make sure that the other products do not contain ingredients that may interfere with the effectiveness of Retinol. For example, avoid using products that contain salicylic acid or benzoyl peroxide, as these can irritate the skin and reduce the effectiveness of retinol. It is recommended to apply Retinol Serum in the evening and combine it with a moisturizer to provide the skin with sufficient moisture.