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.
I had anal sex with another male. My condom broke after 30 seconds and I then put another condom on. He did try to penetrate me but it hurt and i asked him to stop within 5 seconds or less. I did clean my penis after 10mins of this happening and then got onto pep within 5 hours of possible exposure and currently taking 1 12hr tablet and one 24hr tablet. How likely is it for me to have HIV after one exposure and that I took PEP within 5 hours.
I don’t know the status of this person and he seems to be a sex worker. He did say he had been tested a month ago and that it was negative but deleted the text. He has a test booked for 1st of march 2022 and he said he will let me know. If there any other way to know if this person is telling me the truth? I assume that he wouldnt be able to go for a test if he was positive already which bring me some what less anxiety.
Hi Sid, taking PEP this early is great. The earlier the better. 5 hours after exposure is very quick and will give PEP the best chance of working. Adjusting the 12 hour pill by 1 hour/day is suitable. 10 minute increments each day is not required. Meaning you can be at your desired time within 3 days. Adjusting my 10 minutes would take 18 days which is the majority of the course of PEP.
I took PEP within 5 hours of exposure, how likely is it to work? I am wanting to get the 12 hour pill to a more convenient time e.g. 8am instead of 5am. To do this I am wondering if I can take this tablet 10 minutes later each time (12hr) to get to 8am over the course of a week or so. I am happy to keep the 24 hour pill the same time each day.
Hi Lil, after 3 weeks PEP is not going to have any effect. Please refer to out testing and transmission F&Q for any further information: https://i-base.info/qa/factsheets/hiv-transmission-and-testing
I think I have been exposed to sex to a positive person n I have just realized after 3 weeks can pep still work
Hi Worried, your test is conclusive. As you have waited more than 6 weeks after PEP your result is accurate. You are HIV negative.
4th Generation test cmia negative after 51 days of pep (80days of exposure) is it conclusive 100 percentage
Hi Bold, yes this test is conclusive. As you have waited 12 weeks after PEP you can consider this test conclusive. You do not have HIV.
After pep course I tested at 12 weeks post pep (16 weeks post exposure) with a Rapid blood antibody test (Alere determine) which came out Negative.
Am I at the clear?
Hi Muhammed, unfortunately a test immediately after finishing PEP is not accurate. What type of test are you using? If it is a 4th generation antigen/antibody test you will need to wait 6 weeks to be sure. If it is a rapid antibody test 90 days is required. This is a link regarding anxiety and fear while waiting for test results: https://i-base.info/guides/testing/hiv-testing-feelings-of-fear-anxiety-and-guilt