Ritonavir is a popular anti-infection drug used in the treatment of infections associated with the Human Immunodeficiency Virus (HIV). Ritonavir is often prescribed alongside other similar drugs in order to control symptoms of the virus. Ritonavir lowers the level of HIV in the blood stream. It may help in preventing or slowing the progression of HIV into AIDS. However, it cannot cure HIV altogether. Ritonavir requires a prescription, and cannot be purchased over-the-counter. It is taken orally in the form of a tablet, or a liquid solution.