, , , | PubChem = 5538 | DrugBank = APRD00362 | chemical_formula = C₂₀H₂₈O₂ | molecular_weight = 300.435 g/mol | bioavailability = | protein_bound = > 95% | metabolism = | elimination_half-life = 0.5-2 hours | pregnancy_category = | legal_status = | routes_of_administration = }} Tretinoin is a retinoic acid (vitamin A) drug commonly used to treat acne vulgaris and keratosis pilaris. It is available as a cream or gel (brand name Retin-A®). It is used by some as a hair loss treatment.

Clinical Pharmacology

Although the exact mode of action of tretinoin is unknown, current evidence suggests that topical tretinoin decreases cohesiveness of follicular epithelial cells with decreased microcomedo formation. Additionally, tretinoin stimulates mitotic activity and increased turnover of follicular epithelial cells causing extrusion of the comedones.