Nelfinavir is a type of medication used in the treatment of HIV. Some synonyms for the word nelfinavir include Viracept, AG1343, and nelfinavir mesilate. These terms are often used interchangeably and refer to the same medication. Nelfinavir works by blocking an enzyme called HIV protease, which helps the virus replicate itself. By inhibiting this enzyme, nelfinavir can slow down the progression of the disease and prevent further damage to the immune system. While nelfinavir is considered an effective treatment for HIV, it may cause side effects such as diarrhea, nausea, and stomach pain in some patients. It is always important to consult a healthcare provider before starting any new medication.