Prescrire Int. 2008 Aug; 17(96): 154-6(1) Isotretinoin, a vitamin A derivative, is marketed as an oral treatment for refractory severe acne. It is known to carry a risk of severe birth defects. The skin tends to become dry and fragile during isotretinoin treatment; (2) Some adverse effects of isotretinoin are caused by damage to the intestinal mucosae. These effects include bloody and mucousy diarrhoea, colitis, ileitis (sometimes severe and necessitating surgery), and aggravation of inflammatory bowel disease such as Crohn's disease; (3) Isotretinoin can affect all mucous membranes, causing multiple disorders of varying severity, affecting: the eyes (conjunctivitis); ear, nose and throat (epistaxis); respiratory tract; gastrointestinal tract (colitis); and urinary tract; (4) Patients must be informed of the risk of mucosal damage and especially of intestinal disorders associated with isotretinoin therapy. Isotretinoin should be borne in mind as a possible cause when a young patient presents with gastrointestinal disorders, and its withdrawal should be envisaged. Isotretinoin is an additional risk factor in patients with a personal or familial history of inflammatory bowel disease.