Raltegravir is an antiretroviral medication used to treat HIV (human immunodeficiency virus) infection. It works by blocking the action of an enzyme called CCR5, which is used by HIV to enter and infect cells in the body. Raltegravir is typically taken as a single daily dose and is generally well tolerated. However, like all medications, it can cause side effects, which may include nausea, vomiting, diarrhea, and headache. It is important to speak with a healthcare provider before starting any new medication, including raltegravir, to determine if it is appropriate for your individual needs and to discuss any potential side effects or interactions.