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
Please help, I had unprotected sex with a person who is HIV positive and I went on PEP, 4 days after the 28 day course I was exposed again and I went on PEP again. When is the right time to get tested again? I am seeing a person who is positive and she is only been on meds for a month.
Hi Tonny,
When someone is on PEP they need to take the full course of medication, then wait 28 days to test. It won’t help to test midway. For info about what an Elisa test can and can’t do please see here: https://i-base.info/guides/testing/appendix-3-how-hiv-tests-work
I am on my 14th day while taking PEP, I did an HIV Elisa test and it showed a viral load 40pcs.what are the chances of PEP clearing the virus after the 28day course.
Can I transmit HIV while on PEP?
Hi John,
HIV can not be transmitted if your partner has been taking HIV treatment (ART) and has an undetectable viral load. Please see U=U. So if this is the case, there’s no risk of HIV.
However, it’s a good idea to continue with PEP and take the complete course. Please see this link full info about PEP.
I am on my second week on PEP, now I had an unprotected sex with an HIV woman. Should I continue with my medication or I start again? Are there any chances that I might contract hiv
Hi Worried Man,
It’s recommended that you have an HIV test 28 days after finishing PEP because PEP can delay HIV infection. So it’s great that you’ve tested negative.
For more info about PEP and PrEP, please see this link.
Hello, finished 30 days of PEP and tested negative. This is after a sexual encounter with a HIV positive lady. Is the test result conclusive?
Hi Roy,
PEP needs to be taken within max 72hrs after an exposure, the sooner the better.
Is Pep effective at the 49th hour post exposure?
Hi John,
I hope you don’t mind but I’ve shortened your comment a bit.
It’s great that you started PEP if you thought this was a risk for HIV. Please see this link for all info about PEP. This info includes having another HIV test 28 days after finishing PEP.
Please talk to your doctor if you think you are allergic to these HIV meds. That’s to make sure that if you need to take them again it will be okay.
And please see the following links for reported side effects for these meds.
Raltegravir: https://i-base.info/guides/3567
Truvada: https://i-base.info/guides/746