Question

Late with the after sex on-demand PrEP dose.

Hello for all. I started 2-1-1 prep, took 2 pills 3 hours before sex. Then I took second pill after 24 hours after sex, not 24 hours after the first 2 pills – I have delayed the second pill by 3 hours. I’m still continuing taking PrEP every day because I have sex but I am just worrying is it ok to delay the second dose by 3 hours? Thank you for reply.

Answer

Hi, how are you doing?

Being 3 hours late on the second dose is not likely to cause a problem. The initial double dose will have increased the drug levels within your body more than a single dose anyway. These drugs tend to remain at the required drug level within the body for more than 24 hours.

While it is best to take the medication as routinely as you can, being late by 3 hours is unlikely to cause you any problem. As you have now continued with daily dosing, PrEP will have remained at effective level within your body.

There is no reason to be concerned after this event,

Josh.

112 comments

  1. Christina Antoniadi

    Hello Aaron and thanks for getting in touch.

    The easy answer is that it makes very little difference.

    That kind of delays (1 or 2 hours) don’t affect the protection PrEP gives you and you can take it next whatever time works best for you – ideally in the morning.

    I am guessing you started with a double dose?

    If not please do from now on as it builds much better protection faster.

    In any case you don’t need PEP.

    You have done well.

  2. Aaron

    Hi, I’m around 2 hours late for my 2nd dose of PrEP:
    – 1st dose: 8am Sat (had oral and anal sex with condom on Sat evening, status of partner unknown)
    – 2nd dose: 9:30am Sun

    Is this still ok? Do I need PEP?
    And for the 3rd dose, should I take it at 8am or 9:30am Monday as well? Thanks!!

  3. Simon Collins

    Hi Emrah, please see the info on dasing here – you don’t need to be exact on the timing:
    https://i-base.info/uk-guide-to-prep/

  4. Emrah

    Hi All
    I took 2 Prep at 6.00 p.m on Friday
    1 Prep at 5pm Saturday,sex at 7pm
    1 Prep at 3.00 a.m Monday so I took last Prep 9 hours I am uncertain if this requires pep or not and quite concerned because of the uncertainty.
    Thank you.

  5. Simon Collins

    Hi Roman – the link I sent before answers these questions with all the info there is about PEP:
    https://i-base.info/uk-guide-to-prep/

    Also at this link with more info about this service:
    https://i-base.info/qa/11844

  6. Ronan

    Hi Simon,
    Thank you for the reply. I probably should have phrased it better. I was more concerned about whether the late tablet would require asking for PEP or whether I still had protection.

    Just to refresh,
    I took 2 tablets at 6pm Wednesday.
    1 tablet 6pm Thursday, sex at 11pm.
    1 tablet 8pm Friday.
    The last one was taken at 1am Sunday; so 7 hours late of my routine, but 5 hours late if I account for the previous being late by two hours as well.
    I am uncertain if this requires pep or not and quite concerned because of the uncertainty.

    Thank you for your help

  7. Simon Collins

    Hi Roman, please see this guide which explains PrEP dosing:
    https://i-base.info/uk-guide-to-prep/

  8. Ronan

    Good morning, I just want to run this past you.
    I take on demand prep.
    I took 2 tablets at 6pm Wednesday.
    1 tablet 6pm Thursday, sex at 11pm.
    1 tablet 8pm Friday.
    The last one was taken at 1am Sunday; so 7 hours late of my routine, but 5 hours late if I account for the previous being late by two hours as well.
    I am uncertain if this requires pep or not and quite concerned because of the uncertainty.
    Thank you.

  9. Christina Antoniadi

    Hello EC,
    no PrEP taken as prescribed can protect you to not need PEP.

  10. EC

    i took tenofovir/emtricitabine for on demand prep 2/1/1. Do I still need to take PEP to improve protection rate? Thanks.

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