Q and A

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. Ken •

    Hello, when you say 6 weeks after the last dose of Pep is valid to conclude with the 4th generation test, is that possible or is it a definite negative conclusion? I tested after 8 weeks with hiv RNA test and 10 weeks with 4th generation lab test. but since then I have all the symptoms like high fever, chills and now swollen lymph nodes causing pain in the ear. Does that mean I’m seroconverted due to Pep? Do I have to get tested again?

  2. Josh Peasegood •

    Hi Mark, a Bioline test is a 3rd geenration test. The result is only conclusive from 12 weeks after the last dose of PEP.

    It is encouraging that you have tested negative at 8 weeks but you do need to wait a further month to confirm the result.

    More information about testing can be found here: https://i-base.info/qa/factsheets/hiv-transmission-and-testing

  3. Mark •

    Hi Doctor, I had protected sex unfortunately the condom bursted. After immediate hiv test with my partner the results for her were positive to hiv and I was negative. In the 72th our after exposure I was introduced to PEP which I took past 28 days to 60days following much worries, it’s now 8 weeks since last tablet of PEP and my test for hiv using bioline is negative, should I rely on this results or need more tests since I still have flu like symptoms among other signs?

  4. Josh Peasegood •

    Hi Nguon, for more information about testing please see here: https://i-base.info/qa/factsheets/hiv-transmission-and-testing

  5. Nguon •

    Hi doctor
    I has broken condom during sex with unknow girl . After 24hour i get pep, during pep i was rah, i so worry and worry, but i continuo pep until 28 days.
    After pep 4 weeks i test negative.
    Can this result chang at 6 or 8 weeks later???

  6. Josh Peasegood •

    Hi Alessandro, a 4th generation test is only conclusive 6 weeks or more after an exposure. While this is a very low risk exposure, if at all, a test at 4 weeks is not conclusive.

    More information about testing can be found here: https://i-base.info/qa/factsheets/hiv-transmission-and-testing

  7. alessandro •

    Dear, i was involved in protected vaginal sex and somehow protected oral with an escort. i tested negative after 29 days with 4th gen. i want to know despite the fact that i used condom and there are too much information in internet, do i need to test after 6 weeks? thanks

  8. Simon Collins •

    Hi Erick, you keep posting comments but all the info to answer your Q’s are at the link I sent uou earlier about PEP – please take time to read this:
    https://i-base.info/qa/factsheets/pep-faq

  9. ERICK •

    Hi doctor! , I exposed to HIV on 16 Dec 2023 I started pep(TLD) 13hrs after exposure which i took for 30 days. But after finishing pep on 16 Jan2024 I started to have symptoms like fever and rash and flu like symptoms. I took antibody test 4weeks after pep came back negative! But I steel having flu like symptoms until to day! which are fever, headache ( pain behind the eyes) ,night sweats and joint and muscle pain. I did final test yesterday on 16 April 2024 which is Antibody only test(3rd gen) on 13 weeks after pep and 17weeks after exposure, the results was Negative. specimen used was blood from the vein. Can this results change into positive after final results yesterday?

  10. Simon Collins •

    Hi Erick, everything we know about PEP. including to answer your Q is here:
    https://i-base.info/qa/factsheets/pep-fa