In addition to sexually transmitted infections, unprotected sex can carry other health risks for HIV-positive people. There have been cases reported where a person with HIV has been reinfected (or superinfected) with another subtype or strain of HIV that is resistant to certain anti-HIV drugs.

It is not known how common reinfection (or superinfection) with HIV is. Although reinfection appears to be rare, there seem to be some factors that might increase the risk of it happening. Nearly all the reported cases of reinfection occurred in the first few years after infection, and in people who were not on HIV treatment. However, there have been some case reports of reinfection in people who had long-term HIV infection.

In some cases, reinfection has resulted in the person's HIV viral load increasing and CD4 cell count falling. In addition, their treatment options have been limited because the type of HIV they were reinfected with was resistant to some or all of the anti-HIV drugs they were taking, as well as to others they had never taken. But generally, reinfection does not seem to cause serious health problems for most people with HIV.