Question
Does a late third dose on 2:1:1 PrEP mean I need PEP?
26 March 2026. Related: Adherence, All topics, PrEP.
Hi – I’m on the 2-1-1 on-demand PrEP regimen: I took 2 tablets at time 0 (the initial loading dose), then 1 tablet at 32 hours (8 hours late, instead of the scheduled 24-hour dose), then 1 tablet at 48 hours. I plan to take one more tablet at 7 PM this afternoon.
I had unprotected receptive anal intercourse, where I was the receptive partner (the one being penetrated). The other person inserted for only 5 minutes, but there was a brief moment of fast penetration right at the start that caused me pain once. I don’t know his HIV status and he did not ejaculate.
Do I need to start PEP as my third PrEP dose was taken 8 hours late?
Answer
Hi there
Please do not worry about this.
The following information should help you decide on the need for PEP.
- This doesn’t sound like any risk for HIV?
- The initial double dose provides very good drug levels to cover slightly later doses.
- The doses afterwards would still have covered you well.
Based on this situation, UK guidelines would include any need to use PEP.
Please these links for info on PrEP and PEP:
Hello, I did prep 2-1-1 incorrectly by taking the second day dosage 9 hours late (24 hours after sex instead of after double loading dose).
Double Loading dose Friday at 435pm and sex Saturday 130am, second dose Sunday 130am (9 hours late, took 2 just in case), and final dose at 435pm as it was meant to be. I continued with daily prep thereafter for 30 days.
Partner of unknown status but did not react well to me asking. So I will test with RNA and 4th generation tests to put this behind me.
Just wanted to ask you, would the same test conclusivity be applicable if PrEP was taken daily from time of incident until 30 days after (and then stopped before rna test at day 38 and 4th gen at day 45)? thank you!
Hello again Johnny,
Please see my previous answer.
Also for information about testing please see here:
https://i-base.info/qa/11844