Abacavir hypersensitivity reaction after switching from the twice-daily to the once-daily formulation.

A 36-year-old man with HIV infection developed a reaction compatible with an abacavir hypersensitivity reaction after switching from the twice-daily to the once-daily formulation. The switch was determined by a more convenient intake. The patient was treated with abacavir twice-daily plus lamivudine and efavirenz for more than 5 years with no side effects.