Dear Dr Remien, My boyfriend is HIV+ and I'm not. I'm glad to be able to tell you that we haven't had one accident yet. But I'm interested in Post Exposure Profylaxe, because you never know. I heard that when you've used PEP once, and you will be (re-)infected later, you can be already resistent for the drugs that are in the PEP-combination. It seems weird to me, because it's the virus that gets resistant, not the patient, right? Thank you for your time.

Jolanda from The Netherlands

You are absolutely right when you say it is the virus that becomes "resistant," not the person. I have never heard that after taking PEP once, the person is at risk for developing resistance. Resistance develops when a drug is present while the virus is replicating. The presence of the drug "selects" for resistant virus. Therefore if a person is taking PEP AND if they are actually become infected with HIV, then they run the risk of selecting for resistant virus, just as any other person already living with the virus. Therefore it would be risky for someone to keep taking PEP while repeatedly exposing his or herself to HIV, since "resistant" HIV could establish itself and survive within that person.

Keep in mind, PEP is to be used in those emergency cases, when an "accident" occurs. It should not be used repeatedly or as a "planned" strategy or rationale for taking risks. Take care.