Q and A


If PEP is 28 days does this mean PrEP is just for one day?

I know that PEP is for 28 days after exposure but does this mean PrEP before and after that means 1 day?



No, PreP includes more that just one pill.

PrEP can be dosed in different ways and includes both before and after doses.

Most people take PrEP as a daily pill, every day.

Some people – only men – can take PrEP just when they think they will have sex. This is called event-based dosing and the “before” dose is very important.

More information about PrEP including options for dosing are in this guide.


  1. Lisa Thorley

    Hi Ashley,

    If your partner is on medication and their viral load is undetectable there’s no need to use PrEP. Please see here: http://i-base.info/u-equals-u/ If their viral load is detectable then yes you could try PrEP or stick with condoms.

  2. ashley

    Hi my name is Ashley my partner is HIV and am HIV negative I didn’t know he has HIV I went for test two weeks after we had sex twice can i use prep plz assist me plz

  3. Roy Trevelion

    Hi Yaw,

    This is fine. Taking PEP for an extra 2 days will not make a difference to its effectiveness.

  4. Yaw

    My doctor prescribed Kaletra and Combivir as PEP for 28 days but I took it for 30 days . Can this affect the effectiveness of the medications ???

  5. Lisa Thorley
  6. Chika


    I will like to understand repeated HIV testing after PEP

    I took PEP for 30 days, 20hrs after exposure and after baseline Hiv test was negative.
    I ran HIV test on the 30th day counting from the first day I started PEP (i.e the day the PEP finished).
    I ran confirmatory test 91 days counting from the first day i started PEP.

    All tests were negative…is this procedure right from my doctor?




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