REZOLSTA is a combination antiretroviral medication used in the treatment of human immunodeficiency virus (HIV) infection. It contains two active ingredients: darunavir and cobicistat. Darunavir is a protease inhibitor that works by blocking the protease enzyme, which is essential for the HIV virus to replicate and infect new cells. Cobicistat, on the other hand, does not have antiviral activity of its own but is included to boost the effectiveness of darunavir by increasing its concentration in the blood. This combination allows for a more potent and effective suppression of the viral load in patients, helping to prevent the progression of HIV to acquired immunodeficiency syndrome (AIDS). REZOLSTA is typically used in combination with other antiretroviral medications as part of an antiretroviral therapy regimen.