A simple lab exam allows positive people to avoid a dangerous reaction to the HIV med abacavir. (It’s in the nukes Ziagen, Epzicom and Trizivir).

Some 8 percent get a serious allergic reaction (called a hypersensitivity reaction, or HSR) to abacavir. The reaction involves a rash with fever, stomach problems, fatigue and shortness of breath. If people have these symptoms after taking abacavir, they risk death if they stop and start the drug again. Some people get one or two of the symptoms but not the actual HSR. So doubts and worries have reigned.

Now a simple blood or swab test can screen people for the gene that predicts the HSR. If people have the gene, they can avoid the drug; those without the gene don’t need to worry. The screen, ordered by your doc, is called the HLA-B*5701 test, after the gene linked to the drug reaction. Roll ’em.