Question

Is a negative HIV test four weeks after PEP okay?

7 June 2023. Related: All topics, HIV testing, PEP/PEPSE, Southern Africa.

Good day.

Is it possible to test positive after testing negative after completing 28 day of PEP?

Answer

Answer: Simon Collins

Hi

In the UK, people need to wait 4 to 6 weeks after the last dose of PEP before taking a 4th generation HIV antigen/antibody test.

If this test is negative after 6 weeks, then someone is told they do not have HIV. If it is negative after 4 weeks, it means HIV is unlikely, but that a second test should confirm this after a few more weeks.

There is no point taking an HIV test as soon as you finish PEP.

This is because the PEP could just be covering up or delaying a potential infection.

This answer was updated in June 2023 from a question first posted in November 2020. This is because UK guidelines now recommend testing after 6 weeks rather than after 4 weeks.

Please see this link for more information about PEP:
https://i-base.info/qa/factsheets/pep-faq

Simon.

281 comments

  1. Jessie •

    I had unprotected sex with a random man at 2 am and got PEP also got hiv tested with negative result at 2 pm. Then I had unprotected sex with my boyfriend at 4 pm in the same day. After 28 days of PEP I tested negative.
    My question is there any chance my boyfriend could get HIV from another man cum when we had sex on that day even I tested negative?

  2. Josh Peasegood •

    Hi Missy, yes. After 42 days from the last dose of PEP a 4th generation test is conclusive.

  3. Missy •

    Are test results 43 days after pep conclusive using a 4th generation test?

  4. Josh Peasegood •

    Hi Harry, no the index value has nothing to do with this. As long as the value falls below 1 it means that you are negative. It doesn’t actually matter what the number is.

  5. Harry •

    So one day after completing my pep course I did take an HIV 4th generation test which came back negative with an index value of 0.14 (anything below 1 is considered negative) I do know that this result wasn’t accurate because pep could delay infection or suppress the viral load. My question given that the index for this test is 0.14 would it mean that it could get higher 4-6 weeks after pep? Or does this index value have nothing to do with smoething like that?

  6. Simon Collins •

    Hi Abhi

    Please see this link that answers your questions about PEP, including about testing.
    https://i-base.info/qa/factsheets/pep-faq

  7. Abhi •

    Hi Josh,
    I had a 4th generation test at 38th day after the last dose of pep which came out negative. Are there chances left for infection?

  8. Simon Collins •

    Hi Chris, please see the link here for info on HIV risk, testing and transmission:
    https://i-base.info/qa/11844

    thnks

  9. Chris •

    Hi..

    I had protected sex with a random girl.. Ị don’t know her status though & condom didn’t break.. No blowjob or kiss.. Just penetrative sex… Should i be worried?

  10. Simon Collins •

    Hi Shaun, no one has the right to make another person test for HIV, just because of their paranoia. Here is information about PEP:
    https://i-base.info/qa/factsheets/pep-faq