Q and A


How long do I need to take PEP?

Hi, I have a girl who is HIV positive we have been having sex most days. I am on PEP, but how long should I continue to take PEP. I have unprotected sex everyday???


Hi, how are you doing?

Are you talking about PEP or PrEP?

PEP is used AFTER an exposure and is a course of treatment for 28 days.

PrEP is used BEFORE. PrEP is more appropriate to use. It is a pill similar to PEP but you can take it daily. PrEP prevents HIV transmission and is more effective at prevention that PEP.

If your partner is on treatment then you do not require any medication. If she has a viral load below 200/undetectable there is no risk of transmission. This is called U=U.

ART/PrEP/PEP will not prevent other STIs. A condom is required to prevent other infections if these are a risk.

If you like having sex without a condom, then please talk to your doctor about PrEP. This is a very good way to protect against HIV in the future,



  1. Josh Peasegood

    Hi Lucas, the difference is largely due to how each of the treatments can be studied. It is easier to observe a drug before transmission rather than use a drug which would already require a potential exposure. For more information about this and their effectiveness please see here: https://i-base.info/pep-and-prep/

    For the most part PEP failure is caused by poor adherence with the treatment e.g., starting it later than recommended, or not remembering to take it each day. Both of these contribute to the general lowering of PEPs effectiveness but this will not apply to the individual person when PEP is taken correctly.

    PrEP is more effective because the your body already has protective drug levels before you even come into contact with HIV.

  2. Lucas

    “PrEP prevents HIV transmission and is more effective at prevention that PEP.”

    Where is this information? Are there any studies? I’m on PEP after a high risk exposure, but I am really afraid of its failure, thinking about ending my own life if it fails.


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