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 slept with a woman 21 march and i went for pcr test HIV the second day which was 22nd March and then took my pep ….results came out after 9 days i was negative and my doctor told me to stop the pep…but im still worried.
Hi, transmission of HIV is not always guaranteed every time you have sex. This can be explained here: https://i-base.info/guides/testing/risks-for-transmission Have you had a recent test? While it helps suggest you are HIV negative, if you have tested positive this means that you do have HIV and are at risk of passing on HIV to others.
I had sex with a guy on guy 2 months ago, I told him to get PeP because I’m not sure of my status, and after a 6 weeks he got tested again and the results were still negative. Is it possible that I’m also negative?
Hi Jason, how long ago was this? If it has been within 72 hours of your exposure, PEP (https://i-base.info/pep-and-prep/) will still be able to offer some protection.
If not, it is still likely that you will not have contracted HIV from one exposure. HIV is not readily transmitted and there are a number of factors that change your risk. As an example, being the insertive partner already reduces your risk. Additionally if this sex worker was on medication and undetectable there would be no risk to you at all. This link explains this is more detail: https://i-base.info/guides/testing/risks-for-transmission
Hello everyone,
I had an unprotected vaginal sex with a sex worker and later got to know that she is HIV positive. I am worried a lot that I could have exposed to the Virus and will be HIV patient soon. I’m very nervous about next course of action.
Hi PEP, do you have a reason to think this sex worker is HIV positive? It would be much more likely for them to be negative. The first test you had would have showed you that you did not have HIV prior to this. The second test does not provide much information as a test while on PEP is not accurate – in no way does this suggest you have HIV.
It is very likely that you will be okay. You started PEP quickly and have been taking your medication. The risk of HIV is very small in this case. PEP is for 28 days. There is no need to continue the course for longer than this. In any case, it would be good to keep the additional 2 PEP if this happens again and you will have access to PEP and time to get the full prescription.
Hi there,
I had sex with a sex worker and I didn’t realize my condom break after she and me ejaculate at the same time. I don’t know her health status. I just went to get my PEP within 48 hours. I got Tivicay and Tenof (sorry if wrong spell). Before getting PEP, I got blood test and it’s negative. The doctor said it will be okay. After 2 weeks on PEP, I did a blood test again for HIV and STD/STI. Still negative. Do you think it will be okay? How big the risk could be? As PEP only for 28 days but those bottles contain 30 pills. Should I finish it up to 30 days or just 28 days? Thank you.
Hi Andres, don’t worry about your English. It’s great.
4th generation antigen/antibody testing needs to be done 4-6 weeks after PEP. Like your doctors have mentioned this is because PEP can suppress HIV and will not get an accurate result. At 4 weeks post PEP the test will be 95% accurate and at 6 weeks will be 99% accurate. Any test before this will not be conclusive, however it can help with your anxiety.
Testing negative at earlier points will continue to suggest you are HIV positive. The likelihood increases the later on you wait. Not having any symptoms is very encouraging. Testing the day PEP ends would not be be near accurate. Testing from 3 weeks will start to give you an idea.
(Sorry if my English is not perfect. It is not my first language)
Hello, I started pep at 4/5 hours after an exposure (anal, I was top.) I’m actually on day 23 and I’m really anxious. I know from this amazing blog that a test 4-6 weeks after pep is conclusive but I want to know how accurate is the test just after finishing pep. I just want to have some peace of mind, I contacted two doctors and both told me that pep may, but shouldn’t, delay the hiv testing window, and I would consider a negative test even now (at 23 days) a good indicator of pep success since I started so early. Can you please help me with that doubt, at least to reduce a little bit my anxiety.
In term of symptoms, I don’t haver fever or swollen lymph nodes. I just have a globus sensation on my throat (I think it is that since it is intermittent and it doesn’t hurt, it is just awkward.) Today I started with a kind of dry cough but I think it is more related to anxiety.
Hi Marcel, do you know the status of this sex worker if they were on medication? It is much more likely that they were negative. Also, as you were the insertive parter and the condom didn’t break until the end, the risk is very low.
Lamivudine can be used in combination as PEP, but lamivudine alone is not enough to work as PEP. Usually it is given as a combination of 3 medications (sometimes 2 can be used). It is great that you started so quickly, however lamivudine is not sufficient by itself to be used as PEP: https://i-base.info/qa/4536