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.
Please see this link for more information about PEP:
https://i-base.info/qa/factsheets/pep-faq
Note: This answer was last updated in July 2021 from an original post from December 2011.
Hi BrookChng,
The drugs in PEP can be different in different countries. And more than one drug can be made into a single pill. But what does it say on the box or bottle? It should list the drugs on the patient information leaflet too.
Hi, I sort of played around with a friend and he inserted my penis into his anus. I later realised I had a little wound on my foreskin and probably some strerches near my anus too. He is on low risk to be exposed with hiv for around 2 weeks before doing it with me. However, I am worried so I went to see a doctor and started Pep on my 50th hour. Im a student on low budget so I discussed with the doctor and we worked out a plan. The thing Im worried is that I was told Im being given the cheapest PEP, which is only one pill, which is red and big. But according to what I see online, most people are being given a mixture of few pills. Is there anything wrong with my situation? Thank you!
Hi Peter,
It’s good that you got on PEP before 24 hours. And PEP does work. But also HIV is quite difficult to catch, see this link. However, if they taking HIV treatment (ART) and are stable with an undetectable viral load, there is zero risk, see U=U at this link. You can test 28 days after finishing PEP, see this link.
I had sex with a prostitute the condom broke, I got on pep before 24hrs ,I got the prostitute checked and it was positive, what are my chances
Hi Allan,
If you are not sure you can have an HIV test. i-Base doesn’t have resources to answer questions on testing and transmission. But all frequently asked questions are at this link.
i engaged my self in sex with a lady whom i didn’t know her hiv status, i now experience some cough, pain in the abdomen, fever. should i think a’m hiv positive?
Hi Reggie,
Guidelines don’t recommend benefit of PEP after 72 hours. But perhaps you can look here and work out your risk of HIV. If you used a self-test it needs to be confirmed at the clinic of course.
Hi Roy
I had a condom break during sex and I only realised it after 15 min of sex when i ejaculated and the woman squirted.I tested her after 72 hours of exposure and she was HIV positive. I am negative.I immediatley went to the DR and I am on PEP.I took the tablets at the 80th hour.Will PEP be effective at this time.Please help.
Hi Carol,
PEP needs to be taken as soon after exposure as possible. This is preferably within hours rather than days. Most guidelines have a cut off for PEP of 48 hours after exposure.
Even though in the UK you can get PEP for up to 72 hours it is much less likely to work when it is used this late. The longer the delay the less the chance that PEP will work. But you could go to the clinic and talk about the kind of sex you had and your risk.
If the HIV positive person is on treatment and has an undetectacble viral load there is zero risk of transmission U=U.
hi I had live sex with an hiv positive person but I get to know four days after. can I start on PEP or is there and other option I could do to prevent myself from getting HIV?