This test determines whether the particular virus in your body is resistant to HIV medications.

HIV reproduces rapidly and, as the virus makes copies of itself, small changes (or mutations) sometimes result. These changes can lead to different HIV strains, particularly if the person is taking (or has taken) HIV medicines but the HIV virus is not completely controlled or suppressed. If a strain that is resistant to your HIV drugs develops, the virus will be able to grow even though you are on medication. Your viral load will start to rise. The resistant virus soon will become the most common strain in your body. If this occurs, your provider may order a resistance test to check for mutations in the HIV virus.

A person can be infected with a drug resistant strain of HIV if the infection was from an individual with resistant virus. For this reason, an HIV resistance test is recommended for all people as soon as they are diagnosed with HIV.

Therefore, resistance testing is performed upon diagnosis of HIV and if a medication regimen is no longer keeping the viral load suppressed.