Drug resistance refers to HIV that is resistant to certain HIV drugs and stops those drugs from working properly. Drug-resistant forms of HIV can sometimes be transmitted from person to person—so a person who has never taken HIV medications before can become infected with drug-resistant HIV. A person’s HIV can also change and become drug-resistant. If a person who is on treatment misses doses, the virus can mutate and become resistant to the medication.
All people living with HIV should have a resistance test done before they start treatment, and, in most cases, before switching to a new treatment. Resistance testing can identify medications that may not work against the HIV in your body. Drug-resistance testing can help you and your doctor determine which medicines to include in your HIV treatment regimen.