Dangerous or even fatal skin reactions (Stevens-Johnson syndrome and toxic epidermal necrolysis) with carbamazepine (Tegretol, Carbatrol) are significantly more common in patients with the HLA allele B*1502, based on an FDA MedWatch notice and FDA Press Release (FDA MedWatch 2007 December 12; full-text available online at: www.fda.gov/medwatch/safety/2007/safety07.htm#carbamazepine, FDA Press Release 2007 Dec 12; full-text available online at: www.fda.gov/bbs/topics/NEWS/2007/NEW01755.html, accessed April 10, 2008). The HLA-B*1502 allele occurs almost exclusively in patients of Asian ancestry, including South Asian Indians. Patients of Asian ancestry should be screened for the allele before starting treatment with carbamazepine. Carbamazepine should not be used in patients who test positive for HLA-B*1502, unless the expected benefit clearly outweighs the increased risk of serious skin reactions. Any patients (including those who are HLA-B*1502-positive) taking carbamazepine for more than a few months without skin reactions should be considered at low risk.