What about the chance of HIV developing drug resistance to Truvada for PrEP?

Before you start using PrEP, it is very important to make sure that you are HIV-negative because you run the small risk of developing HIV drug resistance if you are already infected with HIV when starting PrEP. That’s because Truvada is not sufficient on its own for treating HIV; so if you are already infected, the virus in your body could become resistant to that drug. To develop HIV drug resistance means certain medications will no longer keep the virus in check if you are HIV-positive.