An important AIDS drug can cause sometimes deadly liver damage but remains a key option for many patients, U.S. health officials warned on Wednesday. The Food and Drug Administration said doctors should weigh benefits and risks before prescribing the drug, Boehringer Ingelheim’s Viramune, also known by the generic name nevirapine. No serious liver toxicity or deaths have been reported when a single dose was given to prevent mother-to-child transmission of the deadly HIV virus that causes AIDS, the FDA said. Nevirapine is distributed for that use in African countries as part of President George W. Bush’s effort to fight the spread of AIDS. The drug is also used in the United States. Controversy has swirled recently in Africa, with South Africa’s ruling African National Congress accusing U.S. officials of conspiring with Boehringer Ingelheim, a private company based in Germany, to hide nevirapine’s side effects. U.S. health officials dispute the charge. The FDA, in a statement, said cases of liver damage that produce a rash, fever or other symptoms were more common with nevirapine than with other HIV-fighting drugs. Some instances have been fatal, including some in pregnant women.