Question
I missed my timings with on-demand PrEP dosing, should I start PEP?
26 March 2022. Related: Adherence, All topics, PrEP.
I am a gay man and I use on demand PrEP, but I was a bit late with my first single dose after my initial double dose. I was wondering if I am in bad shape and need PEP. To be specific, I took the initial double dose and I had unprotected insertive anal sex 30 hours after that. I took my first single dose 36 hours after the initial double dose. Then I took my second single dose 48 hours after the initial double dose.
Answer
Hi, how are you?
No you do not need to take PEP.
The initial double dose affords you some protection as the higher dose remains in your body longer than 24 hours. This should extend to the 36 hours post the double dose for when you took your next dose. Your final dose was at the right time so this does change anything further.
In general it is best to take the double dose no more than 24 hours before sex. This is when the concentration is highest and offers the best protection. At 30 hours there will still be protection, but not as high as seen in studies demonstrating 24 hour effectiveness.
From this first dose, the subsequent single dose is 24 hours after and the final 24 hours after that. While being closer to the timings help improve the effectiveness, taking PrEP at a less than ideal time will still give more protection than no PrEP. Example of on demand dosing.
Josh.
Hi Lee, I have already replied in detail to the email you also sent.
I am worried because I restarted Prep with a double dose 36 hours+ before unprotected sex with someone who is positive.
I then took a single dose 12 hours before.
Hi Chris, PrEP is still likely to be very effective even if some doses are a bit earlier or later. The double-dose before sex is the most important and helps drug levels over the next two days too. Please see this guide for more info:
https://i-base.info/uk-guide-to-prep-february-2024/
Hi i took my single dose 41 hours after the double dose
I have no cuts and it was insertive anal
Should I continue ebp or should i use pep?
Hi Simon, thanks – I answered your previous comment just now too. It doesn’t sound like you have anything to worry about. If it helps you worry less, perhaps take an extra pill the following day – ie 2:1:1:1.
Hello a bit concerned and would like your advice on whether I should take PEP as I am still within the window. My dosing was as follows:
Day 1 1430: initial 2-pill dose of prep
Day 1 17:30 unprotected insertive anal sex
Day 2: 2230: second 1-pill dose (8 hours late)
Tomorrow (Day 3) I intend to take the third single pill dose according to the original schedule at 1430.
Additionally, and this is going to sound really silly. Just now when I took my second dose, I was so panicked to be late that I don’t think I swallowed properly and I could feel it only slowly going down my oesophagus for an hour or more despite drinking lots of water. This could also just be my panicked imagination … but does it impact the advice you would give in this situation?
Appreciate the clarity you bring in this forum.
Hi Simon, this all sounds fine but it is easy to take additional doses for the day after and day after that if you want to. I am not a doctor though.
Would like to seek your advise as to whether I need PEP as I am still within the window. Was attempting to use EBD but messed it up
Day 1: 1430 Double dose
Day 1: 1730 Insertive penetration unprotected
Day 2: 22:30 second dose (single pill) 8 hours late
Intend to take the third dose on time 1430 tomorrow
Hi Thapelo, as you are taking it within an hour of your normal time it will still be effective.
It is best to stick to your normal time as much as possible. Being later/earlier can risk the treatment not working as well when falling outside of the hour. Have you considered setting an alarm to remind you, or using a different time that is easier to take it more regularly?
I would like to ask something..
I am a gay man and taking a daily dose prep ..normally i take prep at 18:00 ..2 days before sex i took it around 20:00 the following day 18:58 then during the day of sex at 18:35..the following day later at 20:00 and the following day ..will this be effective ?