Q and A

Question

Will taking PrEP late work with on demand dosing?

Hi, I take PrEP with on demand dosing and after having sex after my first double dose i remembered my first dose post sex on time. However, my second dose was 5h late and 3rd dose was 5h late too. Will this affect my level of protection and should i continue taking it 5h late every day?

Answer

Hi

Thanks for your question. The easy answer is that you will probably be fine.

Both the drugs in PrEP stay in your body to allow for a few hours being late with dosing.

It is better to try to take them at the right time.

The after sex doses with on demand dosing only need to be taken 24 hours and 48 hours after the first double dose. Taking an extra dose for a third day will not do any harm though.

If you are still having sex every day though, then continue taking PrEP until 24 and 48 hours after the last time you had sex.

More information on real life examples for on demand dosing.

44 comments

  1. Simon Collins

    Hi Mike, thanks. Please don’t worry about this. Taking a little more PEP from the second double dose won’t do any harm. Please see this newly updated guide to PrEP.
    https://i-base.info/guides/prep

  2. Mike

    Hello there. I have a question. I took my first double dose at 11am. I then had sex that same day from 9 in the evening for a few hours. I took my next dose on time at 11am the next day but took a double dose by accident. We continued sez again till about 3pm. Now, the next day I set my reminder for 11am again and I was probably on autopilot and did take it but I couldn’t be sure that I did so I took another at 9pm. I then continued taking prep for the next 2 days. Is this ok?

  3. Simon Collins

    Hi Jo, it is not clear which pills you took and missed in relation to when you had sex – especially whether or not you took the double-dose before sex. If this was the missed dose, then PEP will be more important.

    It might also depend on when you previously used PrEP and if this included the previous week. i-Base are not doctorsm so perhaps you were prescribed PEP becasue the details show a higher risk or out of caution.

    More info on dosing in included in the newly updated guide to PrEP:
    https://i-base.info/htb/47180

  4. Jo

    Hello. I am doing on demand dosing.

    I had been taking my pills correctly and had sex twice in one day and realized I had no pills left the day I had sex with two guys about 12 hours apart I did not take a dose the next day I got a refill and took a dose. They suggested I go on pep which I thought was crazy as it was just one pill missed. What is your opinion

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