Azelaic acid is another option for the topical treatment of mild to moderate inflammatory acne vulgaris. It offers effectiveness similar to that of other agents without the systemic side effects of oral antibiotics or the allergic sensitization of topical benzoyl peroxide and with less irritation than tretinoin. Azelaic acid is less expensive than certain other prescription acne preparations, but it is much more expensive than nonprescription benzoyl peroxide preparations. Whether it is safe and effective when used in combination with other agents is not known.