This Wednesday, the Food and Drug Administration decided to strengthen the warning on carbamazepine based drugs used for treating epilepsy, bipolar disorder and nerve pain.

The drugs already carried on their label a warning about the rare possibility but sometimes life threatening skin reaction when under carbamazepine therapy. The reactions include Stevens-Johnson syndrome, which leads to multiple skin lesions, blisters, fever, itching, and toxic epidermal necrolysis.

The carbamazepine drug is available under different generic brands being sold by different drug companies. Shire PLC is selling it under the name of Carbatrol, Novartis AG as Tegretol and Validus Pharmaceuticals Inc., a privately-held firm, as Equetro.

The drug labels will show more prominent the warning in an existing black box warning, the toughest FDA’s drug warning, which appears at the top of the drug label.

FDA made new recommendations also regarding testing before administrating the drugs. It appears that the skin reaction when under carbamazepine therapy has a risk of 1 to 6 cases per 10,000 new users of the drug in countries with white populations, but the risk in Asian populations is ten times higher.

This made FDA to ask health care providers to give patients with Asian ancestry a genetic test before administrating the drug. This recommendation will be also included in the black box warning.

All drug manufacturers have agreed to the labeling change.