Tretinoin is the acid form of vitamin A and so also known as all-trans retinoic acid or ATRA. It is a drug commonly used to treat acne vulgaris and keratosis pilaris. It is available as a cream or gel (brand names Aberela, Airol, Renova, Atralin, Retin-A, Avita, or Stieva-A). It is also used to treat acute promyelocytic leukemia (APL), and is sold for this indication by Roche under the brand name Vesanoid. It is also available as a generic.