How should topical tretinoin be used to treat acne vulgaris?

Tretinoin is applied once per day to affected areas. It should be applied in the evening to minimize photodegradation. The strength and formulation depend on the severity of the acne and the tolerance of the individual patient. After washing the face, the patient should wait 20 to 30 minutes before applying the medication, or use a hair dryer to blow-dry the face before application. The periocular skin, mouth, and angles of the nose should be avoided, because these are more susceptible to irritant reactions. The medication should be applied sparingly to dry skin. Care should be taken when using other topical preparations, such as benzoyl peroxide or antibiotics in conjunction with tretinoin, because the irritant effect of these medications is additive.