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.
Can someone get infected when they had unprotected sex while on PEP.
Hi Sam,
What’s the problem? Please let us know.
I have a problem with pep
Hi Chris,
We don’t have resources to answer more questions about testing and transmission. But please see this link for all FAQs.
It’s a good idea to talk to your doctor about any symptoms you have.
I had unprotected sex almost 3weeks ago but then I had gone for a syphilis and hepatitis also cbd and er test which the dictor told me it comes along as sti they were all fine but the doctor said I will do hiv test in 6weeks but prior to that time I had so much stress from work 11am to 11pm but now I had headache like 4days and then stopped later had like a lining inside my mouth and then it all stopped but now I have neusea and my body itches could this be a symptom of hiv because I get worried each an every minute I think about it.
Hi Jannat,
I’m so sorry to hear your story. But it’s good that you’ve started PEP. Are you getting the support you need after being attacked like this? Can the doctor or clinic advise you about it?
However, I’m not clear about your testing results. So while you’re taking PEP, you could ask for another test?
After a course of PEP you need to wait 28 days before testing for HIV. This is because PEP can delay infection.
Hey, I was raped, the next day I run to a healthcare for PEP, first they tested me and the results were negative but because I am so anxious and nervous, i today went for an HIV test and the results were positive but the bothering bid of it is that, the data Maine was reactive, the stat pak was non reactive and the bio line was reactive, the test was repeated with a different sample and the results were the same!! Is there a possibility that it is because of PEP that I’m getting such results? Thank you.
Hi Dave,
It’s good that you’ve started PEP if you think you’ve been exposed to HIV.
But can you talk to your doctor about your symptoms? Some countries use particular meds in PEP that could be more likely to cause a reaction. If this is happening you can ask to switch your PEP meds.
It’s a good idea also to check with the doctor that these symptoms are not a response to HIV. You may need another HIV test.
Can you still get hiv symptoms when on pep?
Hi Spencer,
As I said it’s not possible to answer your questions unfortunately.
There is actually very little data on the effectiveness of PEP. This is mainly because HIV is already such a difficult virus to catch.
Any study would need to include many thousands of PEP cases to start to see anything significant.
So even though some PEP studies report low numbers of infections – often none – these studies usually only include a few hundred people when looking for something that might only have a 1 in 500 chance of occurring anyway.
Please see this Q&A on only taking 26 days of PEP.