Q and A

Question

Is a negative HIV test four weeks after PEP okay?

Good day.

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

Answer

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. Jomon

    Hai josh I used a 4th generation test after 84 days post pep my swollen lymph nodes and white tongue is not going

  2. Josh Peasegood

    Hi Tone, your test results for HIV are conclusive. You do not have HIV and do not need to continue testing.

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

  3. Tone

    I tested myself at 30 days after exposure ag/Ab after that with finger test at home twice between,40 and 60 days than 91 days at clinic oral test but using blood than last 5 days before my last test 4 and half months with ag/ab test I got hpv vaccine

  4. Josh Peasegood

    Hi Sail, yes a 4th generation test will be conclusive from 42 days after an exposure. This test would not need repeating.

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

  5. Sali

    Hi
    I had unprotected sex a month ago, and now I’m stressed about HIV. Is it reliable to test after 45 days? Or should I wait 3 months for it? And if I get a negative result, should I repeat it after 3 months of exposure?

  6. Josh Peasegood

    Hi Jamon, what was the type of test you used? A 3rd generation would be conclusive at 90 days (though at 84 days it is almost sure that your result is conclusive). A 4th generation test only needs wait 42 days until after the last dose of PEP.

    A white tongue and swollen lymph nodes in your armpit are not suggestive of HIV alone. It is still a good idea to have another test for HIV to be sure of your status, but if these symptoms continue you should speak with your doctor for further causes.

  7. Jomon

    Tested 84 days after pep result came negative,now 120 days white tongue and armpit swollen lymph nodes did I need to test again for hiv

  8. Josh Peasegood

    Hi Aarif, using a combo test the earliest you can confirm your result is 42 AFTER the last dose of PEP. As you finished PEP January 4th, you can conclusively test Feb 15th. You will not require any further testing.

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

  9. Aarif

    Hi sir
    Today my 45of the day I’ll do test in hiv combo test???
    And pep complete 28day
    My first does Dec 8
    My last does January 04
    Today January 19
    So I do the test plz tellme

  10. Josh Peasegood

    Hi Unknown, not this is not advisable. A 4th generation test will give a conclusive result after 42 days/six weeks. You do not need to wait any longer to confirm your status.