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 took PEP after being exposed to the virus after 7 days (Atripla) I decided to take a test after ,4 weeks I tested negative, what are the chances of testing Positive I need to know so I can be prepared,my partner didn’t know that he was possible as well,
Hi Ade,
First of all, it’s not easy to transmit HIV. So having sex once without a condom doesn’t mean that your partner will get HIV. Actually, luck has a lot do with it.
But the great thing is that you’ve been taking HIV meds for 4 months. This would have dramatically reduced your viral load. And your viral load could even be undetectable now.
You want him to be safe. But is there a reason why you are afraid of telling him? Is there someone at the clinic who can support you? Being honest can be the best way, but you shouldn’t put yourself in any danger.
Hello. please I need a very urgent answer. I am HIV positive and I have been on drugs for over 4 months, though not knowing my viral load yet but I adhere to my drugs. 36hours ago I had an unprotected sex with my partner for the first time and he is not aware of my status. Since then have not like myself thinking that I should let him know so he can start PEP before 72hours. One mind is telling not to tell him of my status that he’s gonna be safe because I am on drug and the sex occurred few hours after taking my medication for that day. Another mind is telling me to let him know before 72hrs. Am confused and am afraid of what would happen after telling him, Nevertheless I want to safe him.
please what can I do in this situation please?
Hi Roberto,
Yes you can relax now.
Hi,
Thank you very much for your answer above.
I have had protective insertive anal sex and received unprotected oral sex on two separate occasions with a HIV-positive guy about 2 months ago. Note: He told me that he was positive after our second sexual contact and within 48 hours I was put on PEP.
A few days after I finished taking PEP, I received a 4th gen antiboday and P24 Duo test, and was negative.
Can I relax now?
Thank you very much
Hi Sammy,
If you have sex without condoms when you’re taking PEP this can protect you from HIV. But how is your partner Saammy? I hope she is well.
If she is regularly taking HIV treatment (ART) and her viral load is undetectable you could have sex without using condoms. Please see Undetectable = Untransmittable here.
I am HIV Negative, i had an unsafe intercourse with an HIV positive female partner who is not on any treatment so i was placed on PEP within 48hours and on the 9th day of within the time i was still using the PEP i had unsafe intercourse with her again, can the PEP still protect me as i am still using the PEP till complete days.
Please explain my chances pls
Hi Portia,
Unfortunately i-Base doesn’t have resources to answer questions about testing and transmission. Please see this link for frequently asked questions about this.
Taking PEP (post-exposure prophylaxis) is recommended within 48 hours, with some guidelines recommending you start PEP within 72 hours. PEP is unlikely to work 17 after exposure.
Hello please if you run an HIV test on the first response test kits with plasma as sample of the patient and it shows postive type 1&2 faintly and with whole blood as sample and it shows negative but a confirmatory test was run that is Oral Quick and ELISA but they tested NEGATIVE. And lastly PCR was done to confirm and the result came out less than 20 copies. my question is, can the person transmit the virus when he have with some one?
Again if some one had sex with this person can he take prophylaxis after 17 days after exposure.
Thank you.
Hi Etchah,
If the girl who had sex with is on treatment and her viral load is undetectable there isn’t any risk at all. Please see Q’s 9 and 14 here: http://i-base.info/qa/what-are-the-most-asked-questions