Viramune is prescribed for advanced cases of HIV. HIV---the human immunodeficiency virus that causes AIDS---undermines the immune system over a period of years, eventually leaving the body defenseless against infection. Viramune is generally prescribed only after the immune system has declined and infections have begun to appear. It is always taken with at least one other HIV medication such as Retrovir or Videx. If taken alone, it can cause the virus to become resistant. Even if used properly, it may be effective for only a limited time.

Like other drugs for HIV, Viramune works by impairing the virus's ability to multiply.