PEP is usually given when unprotected sexual intercourse (anal or vaginal) has occurred with a partner who
- is likely to be HIV-positive
- is definitely HIV-positive, and HIV is detectable in blood. (This is not necessarily the case with effective HIV therapy.)
Other situations in which PEP may be required:
- A member of medical staff has injured themselves with a syringe or other instrument that was previously in contact with the blood of an HIV-positive patient.
- When injecting drugs, someone used a needle that an HIV-positive person had already used.
A doctor will decide whether PEP is sensible after a counseling session in an outpatient clinic or doctor's practice. It is helpful if the partner can come to this discussion to give information about their HIV infection and also about any therapy or drug resistance.