Question
Have I done on-demand PrEP right?
27 July 2022. Related: Adherence, All topics, PrEP.
So I have a question. Not sure if on-demand PrEP works like this.
Thursday: Took 2 pills at 4pm (didn’t have sex as expected).
Friday: Took 1 pill at 4pm. Had sex at 2AM
Saturday: Took 1 pill at 630pm. Had sex at 9pm.
Sunday: Took 1 pill at 3pm.
Monday: Took 1 pill at 3pm
Did on-demand prep work with this regimen. This is my 1st time doing it.
Answer
Hi, how are you doing?
Yes. This is how on-demand PrEP works.
As long as you had the double dose 2-24 hours before your first sexual encounter and 2 single doses after your last, PrEP will work. This is what you did.
As you kept your PrEP at a similar time each day throughout, PrEP will have worked.
Josh.
Hi Hugo, no this does not change anything. You have taken PrEP correctly. You only require two doses of PrEP after sex at your normal time. This is regardless of the time you have sex.
Stopping PrEP on Sunday at 9am is correct.
Hi! I’ve been taking PrEP for a week, (2 pills for the initial dose and after that single doses all at 9am), but I only had sex this friday (between 10pm and 1am). I took a pill on saturday 9am and the last one on sunday 9am. Is it right? Does it change anything that sex continued past midnight? Should I take another one today (monday)?
Hi Gabriel, PrEP needs to be spaced out to ensure there is enough time for PrEP to work.
Taking doses sooner is not going to speed up how it works. PrEP requires a certain amount in the body to work and below this it isn’t effective. This is why daily doses are required.
Taking the additional dose sooner is going to increase how much PrEP is in the body, but the body is unable to use this much and the PrEP will be wasted.
For more information about on-demand PrEp please see here: https://i-base.info/guides/prep/real-life-examples-for-on-demand-dosing
If I have sex and take the second dose (1 pill) on the same day, and the third dose (1pill) only one day after I had sex then why is it recommended you keep taking 1 pill until 2 full days after you last had sex for those that have sex on subsequent days? What I mean is, if I only have sex once, is it effective to have taken just one pill only 24 hours after (3rd dose of the initial 2-1-1 regimen)?
Hi Ace, yes it is better practise to do this. As an example, take the initial double dose at 14:00 on Monday, sex later on at 22:00 on the same day. Then on Tuesday and Wednesday take the single dose at 14:00 each day. The time of sex should not effect the time you take PrEP.
Hi Josh,
Thanks :) But would you say going forward, its better practice to take the followup doses 24 and 48 hours after the first dose? Ace.
Hi Ace, this is not likely to be a problem. As the initial dose is a double dose, there is a higher concentration of PrEP in your body than would be fro a single pill. This will allow for you being late in your following doses. Being 12 hours late is going to be covered by this initial double dose.
Hi Josh,
I’ve got a similar question. I may have not taken the on-demand PrEP exactly as I should’ve.
I took the two pills within the timeframe of 2-24 before engaging, but the two doses came 24 and 48 hours after I’d finished engaging, rather than 24 and 48 hours after the first two pills. I think I’d misread the instructions. So because of the timings, the follow-up single tablets may have been likely up to around 12 hours too late. Have I not done it properly?
Ace.