<p>Some myocardial degeneration has been noticed in rats and mice. The most commonly reported adverse reactions of at least moderate intensity (incidence ≥10%) in adult HIV-1 clinical trials were nausea, headache, malaise and fatigue, nausea and vomiting, and dreams/sleep disorders. Serious hypersensitivity reactions have been associated with abacavir which has been strongly linked to the presence of the HLA-B*57:01 allele. This reaction manifests itself in patients within the first 6 weeks of treatment. Patients should be tested for the presence of this allele as recommended by the U.S Food and Drug Administration (FDA). </p>