Question
Do I need PEP if I only took on-demand PrEP an hour before?
2 May 2020. Related: All topics, PrEP.
Hi, I have been on daily prep for HIV for 4 years. Due to covid-19 I was stopped taking my prep for 3 weeks. Yesterday I was visited by a girlfriend around 20:00 hrs so I took 2 tablets of lamivudine/tenofovir around 21:00 hrs we started kissing and we ended up having unprotected sex. Am worried since I did not wait for 2hrs to 24hrs before sex. Am I going to be ok or I should sex for PEP? Please help since am running of time for PEP.
Answer
Hi there
Don’t worry about not quite being two hours. At least one of the drugs (emtricitabine) is already active within 30 minutes and the other takes much longer so an hour either way will be okay.
Please make sure you take another single pill 24 hours after the first dose, and another one 24 hours after this.
Using PrEP like this is called on demand dosing.
See here for more info: Taking PrEP on demand and: Real life examples of PrEP on demand dosing.
Hi Jayden, yes. The UK 2024 draft BASHH guidelines include that the two different versions of oral PrEP can both be used in the same ways. These are the latest UK guidelines.
Can Descovy be used for event based dosing?
At the bottom of this article, https://i-base.info/guides/prep/how-to-take-prep It’s stated, “TAF/FTC can be dosed the same way as TD/FTC.” Does this apply to event based/on-demand dosing?
Hello Jason and thanks for the question.
You don’t need to worry.
Taking 4 tablets in a week is the minimum dose for PrEP to be effective.
Also, the double dose before sex is protective even if you took it less than two hours earlier.
The risk is always greater for the receptive partner, not the insertive.
Please continue taking your PrEP tablets as recommended whether you are doing event – based or daily dosing – that’s how you achieve the best level of protection.
You need to remember that PrEP has been tested in clinical trials between couples who did not use condoms.
Everything you are practicing has been studied before.
Please also remember: it’s always best to be on PrEP than not.
I am sending you the below links as I feel you could benefit from some information on PrEP and sexual risk:
https://i-base.info/qa/11844
https://i-base.info/uk-guide-to-prep/
I’m worried as I took 2 PReP tablets only an hour before sex. He told me days later that he might have had contact with someone living with HIV.
I had taken probably 4 doses of PReP the week before that.
What is my risk based on this sort of situation?
Hi Phil, please see this PrEP guide – 4 doses a week will give you full protection:
https://i-base.info/uk-guide-to-prep-february-2024/
Most people taking HIV meds have an undetectable viral load which also has not risk of HIV.
Hi. Today, I had sex with someone who takes Trustiva. I’m not sure how long He’s been on it. They told me he was on PrEP, but I later found out that Trustiva is not listed as a PrEP medication.
I’ve been on PrEP for 6 months, but I’m not always regular with it. I usually take it about at least for 4-5 times a week, though this last two weeks I’ve been taking it consistently. Before this encounter, I took one pill of PrEP, i don’t know if that helps. I was the top during sex, and I’m concerned about the possibility that this man may have detectable HIV. If I suppose that, the worst scenario. Should I see a doctor to get PEP?
Thank you.