Question
Is PEP effective if taken 48 hours after exposure?
2 July 2021. Related: All topics, PEP/PEPSE.
I paid for sex with a woman but the condom tore and I only realised after I was done. There is a high chance that she was HIV positive. I started PEP after 48 hours.
I got a PCR test done 17 days after exposure. It had a less than 20/ml (undetectable) result.
Now between 14 and 35 days after exposure I have had signs of thrush, mild red rash on my face and a couple elsewhere. But no fever or swollen lymph glands.
Can the rash and thrush be because of utter stress and obsession?
My doctor says that the PCR can be relied upon and that I am negative.
Can the PEP have reduced the viral load to less than 20/ml as I took it for 15 days before the PCR test?
Please give your expert advice. I am very anxious. Thank you.
Answer
Thank you for your question.
The risk of HIV from one broken condom is very low. If your partner had an undetectable viral load on treatment, then the risk would be zero. If they were not on treatment the risk might still be only 1 in 300 or lower.
You cannot guess someones HIV status so your assumptions might also be wrong.
You started PEP within 48 hours, so it is likely it will work.
PEP – stands for Post-Exposure Prophylaxis. It is a term used for taking HIV drugs to reduce the risk of infection. PEP usually involves taking a combination of three HIV drugs for one month. The earlier PEP is started, the more likely it will work. Ideally, this should be within a couple of hours. If this is not possible, then still the earlier the better.
Some guidelines include a two-day window to do this (i.e. within 48 hours). After this, effectiveness is much less likely. Other guidelines allow up to 3 days (i.e. within 72 hours). Sometimes this may be more for psychological benefit. For example, if someone is very stressed or traumatised.
No guidelines recommend starting PEP after 72 hours.
After finishing PEP you need to wait a 4-6 weeks before testing.
If the PEP has worked, or the person was not initially infected, this will show as a negative HIV test. The test you did 17 days after the exposure will not be accurate yet.
If the PEP has not worked, this will be shown in a positive test result. Testing 4 weeks after PEP will detect 95% of infections. Testing after six weeks will detect more than 99% of infections. This result doesn’t need to be tested again.
If PEP has not worked, serosonversion usually occurs 1-3 weeks after PEP is finished. However, only 80% of people show symptoms.
Please test 6 weeks after you finished PEP is finished. If you test any earlier, you need to take a second test 3 months later.
Viral load (PRC) tests are not approved to test for HIV. In some cases they can have a role.
Please see a doctor to talk about your symptoms he best way to confirm what is causing them is to see your doctor. He/she will be able to diagnose and treat the symptoms accordingly.
Note: This answer was last updated in July 2021 from an original post from December 2011.
Hi Sean, starting PEP after 72 hours will not be effective. It can still lead to suppression and eventual serocovnersion of HIV. After 72 hours it will only delay and not prevent.
If you have started PEP after 72 hours it is still advised to test from the last dose of PEP in line with the testing windows of whichever test you are using.
Hello Josh! It’s me again Sean. What happens if you take PEP more 72 hours after exposure? Will you still test positive during the window period? As PEP might not be able to work against the virus does the virus still develop and test positive from the day of exposure (42 days test)
Thank you
Hi Siyanda, is your partner now on treatment? and do you know her viral load?
It is great that you have been testing negative. Truvada can be used as PEP. It can be offered as part or the full treatment combination. PEP is usually a 3-drug regimen whereas PrEP is a 2-drug regimen. The addition of the third is based on low evidence and Truvada alone can be enough to work as PrEP. Usually dolutegravir is the third drug added to Truvada to make PEP and can be added during the course of PEP.
Using PrEP long term means you should be testing every 3 months. This is to ensure no transmission. If your partner is on treatment with a viral load below 200 you do not need to be on PrEP. There will be no risk of transmission as explained by U=U: https://i-base.info/u-equals-u/
More information about PEP can be found here: https://i-base.info/qa/factsheets/pep-faq
My female partner has been hiv positive for 2/3 years without knowing therefore she is not on arv treatment yet (Now we have evidence her previous partner infected her), i am still testing negative till today (both lab and clinic). My doctor says i have been lucky since i am circumcised. unfortunately, last weekend we slept without protection as we have been doing past 2 years, the same doctor says i’m low risk she gave me Truvada Prep instead of PEP, saying i need to start Prep right away from now on even through i was recently exposed now knowing partner is positive unlike before when we did not know. My friend who is a nurse says the doctor should have given me PEP first then after 30 days i start Prep, now i am very worried, it’s been 5 days.
Was the doctor right or wrong on this?
Second question, can PEP still have benefits when started in day 5, considering i have been on Prep from day 1 of exposure?
Third question, can i start PEP today but continue with Prep since i will be taking it from now on?
Hi Cindy, yes PEP will work. PEP is effective when started within 72 hours of a potential exposure.
More information about PEP can be found here: https://i-base.info/qa/factsheets/pep-faq
Good day
I started my PEP 44hours after sex, I am not sure if I am paranoid or what it was a safe sex but I feel like what if the was a small amount of fluids that got in me. And the guy bought the condoms what if he tempered with them….. So I decided to start PEP my question is will PEP still work if it was taken 44hours after possible exposure?
Hi Lotex, this is not a high risk exposure. Cutting yourself on something sharp is not a risk for HIV transmission. HIV will only exist outside of the body for a minute or 2. There is no risk in what you have described. Did your doctor start you on PEP?
More information about transmission can be found here: https://i-base.info/qa/factsheets/hiv-transmission-and-testing
Hi, I started my PEP dosage out my extreme fear of infectious diseases since I cut my finger with something sharp like razor on a door of public bus.. I started my dosage around 48-54 after the cut.. So was it a high risk exposure or its just my anxiety? Was i too late to start dosage and I won’t work? Should I stop the dosage?
Hi Sean, PEP will delay testing windows for the length of the time you had taken it for e.g., a 4 week course of PEP will mean you have to wait an additional 4 weeks on any test you do.
It is easier to consider the last day on PEP as the first day of exposure. You can then test 6 weeks after this date with a 4th generation test and have a conclusive result.
More information about testing and transmission can be found here: https://i-base.info/qa/factsheets/hiv-transmission-and-testing
Hello Sir Josh! How long does the last does of remain in the body and affect hiv 4th generation test? I was the one who described about my potential exposure. It sill remains concerned. May I repeat and ask for your opinion! If no precum and that man pressed hi ms penis against my anus. Does this really make me at high risk? Because i have read some information about hiv transmission that only fluid come into contact where my rectum got damaged or just his precum got on my anus and i get hiv?