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.
After completing 28 days of pep and waited for another 4 weeks result is negative. Im anxious to know if this is a good sign that the result will be negative on 6 months ? I still had prolong headaches for 5 months now no fever.
Hi James,
There is no data to show there is any difference between 26 day or 28 days of PEP, so there’s little likely impact on the efficacy of PEP.
For more info please see this Q&A.
Hello,I had unprotected sex on Sunday and Monday we did a test and the lady tested positive and doctor gave me Trivenz and I started it same day and bcos of the side effect I only took 27 tablet am I still at risk pls advice
Hi Arman,
Yes, taking PEP should protect you from a new risk.
Hello
I’ve been taking PEP (emtricitabine and tenofovir & Raltegravir) for two weeks now and was just recently exposed to HIV for the second time about 24 hours ago. The person is recently positive and does have a viral load. CD4 count is unknown. I have 14 days left. Should I add two weeks to this or will I be ok? Should I be worried? I understand that truvada is 92% effective. So since Truvada is what I’m taking daily, I should have a pretty low risk. Right? I also understand that my first exposure could potentially make me positive. But theoretically, if I was never infected or if PEP is working and does work and I’m negative, truvada’s 92% protection rate is what is protecting me from HIV?
Hi Lerato,
What medication were you give for the first 14 days?
It’s not possible for us to predict what the risk is. However, it’s important to know that it’s actually very difficult to contract HIV.
Hi
i was recently exposed and got my Pep treatment within just over 24 hours. i was taking one table a day instead of 2 due to miscommunication and only after 14 days of taking incorrect dosage i realized i had to take 2 tablets which i did for the remainder of the course. now my question is what are the chances of infection in that case?
Hi Angela,
A course of PEP lasts 28 days. Once you have finished the course, you can then have a test.
I was raped with 2guys and they’d not use condoms and because I don’t know there status I rushed to the hospital and I was given PEPs and now am under medication my problem is when is my right time to test my hiv status
Hi Celestine,
Please see this guide to HIV testing and risks of sexual transmission.