Q and A


Will PEP still work if I am not taking it strictly every 24 hours?

I started my 28-day PEP course 4 days ago after having oral sex with a girl and later noticed that my gum was potentially bleeding while giving the oral sex. The third day of taking PEP I was taking the pill late for 1 hour (taking it at 12:30 vs. my usual time of 11:30). The fourth day I was late for another one hour (taking it at 13:30). Today I took the pill again at 12:30 because I felt like taking it at my usual time of 11:30 would have been too soon since the last dose (13:30). Will PEP still work effectively for me? Thank you so much.


Hi, how are you doing?

Yes PEP will still work effectively for you.

PEP needs to be taken regularly every 24 hours for it to work. But PEP does remain in the body longer than 24 hours. For this reason there is some leeway for being late or early with a dose by an hour.

Though it is best to avoid this to ensure you are maintaining a suitable level of PEP within the body. Is 11.30 still suitable for you or is it better moving your regular time to 12.30? To help remember it may be suitable to set an alarm each day to prompt you to take PEP.



  1. Josh Peasegood

    Hi Joe, great to hear that 11.30 will still work for you.

    The different combination you are taking is still okay. Most combinations are time sensitive but as with most medication there still remains some leeway either side of the specified time. In your case being an hour late either side of the recommended time is not going to impact how effective the medication is.

  2. Joe

    Hi Josh,
    Thank you for answering my question.

    I think the 11:30 should still work the best for my schedule.

    By the way, my PEP pills have lamivudine instead of emtricitabine, and dolutegravir instead of raltegravir. Do these affect the duration of PEP in my body (and in turn affect the leeway that I can have in taking the dose late)?


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