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

Answer: Angelina Namiba

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.

846 comments

  1. Ibrahim •

    Hey doctor, I had sex with some one positive, and I started the drugs two days after the exposure, and the dose is being finished in four days time. But I feel headaches and fevers. Could it be that the drugs are not working out, or its a side effect of the pep drugs.?
    Looks forward for your quick response doctor

    Thanks

  2. Lisa Thorley •

    Hi Keneilwe,

    Are you on medication? If you are and your viral load is undetectable your partner won’t be at any risk. For more info, please see here:

    http://i-base.info/htb/32308

    Info about PEP is in the above post.

  3. keneilwe •

    I know that im positive,its about 6 years now.my partner is not.last night(9/21/2017) at about 9pm,the condom burst.i want him to take PEP tonight(9/21/2017)as he does not know my status.i want to protect him as i know he could be infected.is going to be effective if taken within 72 hours.It is the first exposure.Please help

  4. Lisa Thorley •

    Hi Vm,

    Please see the above post. The following may also be helpful:

    http://i-base.info/htb/32308

  5. Vm •

    I had unprotected sex with a positive girl and my penis had a bruise. Can I take PEP at 96 hours?

  6. Lisa Thorley •

    Hi Samuel,

    Yes you can drink alcohol when on PEP and milk. If you’re using PEP, then yes you should use a condom. You should try and take your meds at the same time everyday. What ARVs are you taking?

  7. Samuel •

    1. now i have started to use PEP 12 days ago so, can i drink an alcohol?
    2. what happen if i drink milk at morning since i use PEP drug tonight ?
    3. does sex with condom have any effect when i taking a PEP drug?
    4. what happen if my PEP drug taking time is shifted for one hour?
    5. what should i feed when i taking PEP drug?

    i need your conformation as soon as possible! thank you sir doctor. .

  8. Lisa Thorley •

    Hi Mac,

    Please see Q1 here:

    http://i-base.info/qa/what-are-the-most-asked-questions

  9. mac •

    hallow doc
    I had sex with a positive girl unfortunely condom broke and I started PEP less than 20 hrs and I completed the whole 30 days and I have been tested negative with determine and unigold together last test was 26weeks post exposure which is 6months post exposure and 5months post PEP and it came out negative though I’m feeling sick up and down m
    my question is do I need another test or not
    do this sickness related to PEP or HIV virus
    can I be save to sleep with ma partner without condom

  10. pou •

    I am really happy to read this webpage posts which contains tons of useful information, thanks for providing these statistics.