Atazanavir, sold under the brand name Reyataz among others, is an antiretroviral medication used to treat HIV/AIDS. It is generally recommended for use with other antiretrovirals. It may be used for prevention after a needlestick injury or other potential exposure (postexposure prophylaxis (PEP)). It is taken by mouth. Common side effects include headache, nausea, yellowish skin, abdominal pain, trouble sleeping, and fever. Severe side effects include rashes such as erythema multiforme and high blood sugar. Atazanavir appears to be safe to use during pregnancy. It is of the protease inhibitor (PI) class and works by blocking HIV protease. Atazanavir was approved for medical use in the United States in 2003. It is on the World Health Organization's List of Essential Medicines. It is available as a generic medication. Source: Wikipedia (en)