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 I had unprotected sex with infected man and fourth day was put on pep are there chances of me surviving
Hi Steve,
Please see this Q&A from these Q&As on testing and transmission.
Hi Roy, I have had an unprotected oral sex (received a blowjob and open mouth kissing for less than a minute) and protected vaginal sex (condom was intact during this act). However, I have been given an option for PEP at 50 hrs and I took it since I didn’t know how risky receiving a blow job risk would be. I have completed my PEP for 28 days and got tested with 4th gen laboratory test after 54 days since exposure, the results were Negative. Would that be conclusive or do I need to keep testing it for 3 months?
Please advise.
Hi Itumeleng,
It’s best to start PEP as soon as you can after a risk of HIV. Some guidelines recommend taking PEP within 48 hours of risk. So it’s not recommended to wait until 72 hours after a risk.
Please talk to the doctor about your risk and ask if PEP should be started soon. Here are the frequently asked questions about testing and transmission http://i-base.info/qa/factsheets/hiv-transmission-and-testing.
Hi.I had sex with a partner that is HIV positive yesterday at 19:00 she told me now that she is positive so it is the best time to start to use prep now or I should wait for 72 because I’m scared ( i am only 23 year old)
Hi Smith,
There is a three month window period after exposure, for the confirmatory result to detect more than 99.9% of infections. Please see this link. So it looks like the negative result is confirmed.
But please talk to your doctor about your TB treatment and fevers.
Dear Sir, please advice for my case. I’m a MSM. I had receptive sex at 31 December 2018 with unknown HIV status man. He was drunken and his penis was flaccid. I think that it does not enter into my anus . But he took off the condom before i noticed. So, I’m afraid and took PEP within 14 hours from exposure. I took 28 days course and done Post PEP testings.
at 1 month from exposure-
SD HIV 1/2 test kit- Non Reactive
at 3 month from exposure-
P24 Ag/ HIV 1 & 2 Ab (ECL) test _ Non Reactive
at 3month and 2 weeks from exposure-
HIV 1/2 Ab test kit(Determine) – Non Reactive
at 4 month and 2 week from exposure-
P24 Ag/ HIV 1 & 2 Ab (ECL ) test – Non Reactive
at 5 month and 1 week from exposure-
HIV 1/2 Ab test kit – Non – Reactive.
But I sufferred from TB infection at 4 month after exposure. Now i’m taking anti TB drugs. After 13 days from anti TB drugs I suffered low grade fever from 99° to 100 for more than 1 month up to now. My chest physician told me that it may be due to anti TB drugs (Drug Fever? ) . She didn’t know my sexual exposure history. Today is 5 month and 2 weeks from exposure. I’m afraid that fever would be the symtoms of late seroconversion. What are my chances of HIV negative according to my test results and symptoms?
Do I need the 6 month test to get the conclusive result?
Thanks for your help Sir
Hi Scared and anxious man,
It’s good that you started PEP if you think you’re at risk of HIV.
It’s great too that you have no symptoms this morning. If you have night seats and a sore throat again you should talk to your doctor about it.
You can also talk to your doctor about any other meds or supplements you take along with your PEP to make sure they don’t interact.
I had protected vaginal sex with an African sex worker in India on the 4th of June 2019 at 3pm. I had penetrated twice using the same condom without removing it but ejaculated once, I don’t think the condom is broken since it did not leak after the act. Prior to that I received 10 seconds of oral sex, there was no visible blood. I went to a clinic, tested -ve, and started PEP 41 hours after the act and till now it has been 6 days. Parallely I also have multivitamin occasionally. Just yesterday, I went to the clinic because I had a fright of a small lump near my trapezius, which the doc said was nothing. Since then been very anxious, also last night I had night sweat and prior to that a mild sore throat which went in a while. I am typing this in the morning with no symptoms so to speak and will be having my med at 12pm. Kindly advise as my anxiety is shooting through the roof. Feel terrible when with parents out of guilt.
Hi Peninah,
If you are taking PEP it should protect you from new risks. But having condomless sex while on PEP is not recommended. That’s because you don’t know your HIV status.
That’s why it is important to wait until you finish the course and have done the follow-up confirmatory test.