Isotretinoin (INN), also known as 13-cis-retinoic acid, is an oral pharmaceutical drug primarily used to treat severe nodular acne. Rarely, it is also used to prevent certain skin cancers (squamous-cell carcinoma), and in the treatment of other cancers. It is used to treat harlequin-type ichthyosis, a usually lethal skin disease, and lamellar ichthyosis. It is a retinoid, meaning it is related to vitamin A, and is found in small quantities naturally in the body. Its isomer, tretinoin, is also an acne drug.
Isotretinoin is primarily used as a treatment for severe acne. The most common adverse effects are a transient worsening of acne (lasting 2â€“3 weeks), dry lips (cheilitis), dry and fragile skin, and an increased susceptibility to sunburn. Uncommon and rare side effects include muscle aches and pains (myalgias), and headaches. Isotretinoin is known to cause birth defects due to in utero exposure because of the molecule's close resemblance to retinoic acid, a natural vitamin A derivative which controls normal embryonic development.