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. Shaun •

    Hello Doc, i had unsafe sex on the first of May and started pep on the 3rd .After completing my 28 days treatment I tested negative .After that we also tested the partner with an Oral test she was negative. But since last week i have been experiencing some weird symptoms. Am I being at risk . I want to take another test.

  2. Simon Collins •

    Hi Reelwoon, please see this link on PEP and testing afterwards:
    https://i-base.info/qa/factsheets/pep-faq

  3. Reelwoon •

    I have test negative again after 2 weeks of last pep, and am scared? Advice please

  4. Simon Collins •

    Hi Test

    Please see the info here on PEP that includes testing:
    https://i-base.info/qa/factsheets/pep-faq

    And here for general info on HIV and testing:
    https://i-base.info/qa/11844

  5. Test •

    Hello ,

    I had exposure on feb 8th but I used condom . But since I am not sure about condom breakage , I started using pep from feb10th completed it for 28 days . I took one hiv rapid test after 3 weeks of pep it came negative and took another rapid test at 80 days after completing pep and it came negative . Do I have to another test or I am good ?

  6. Simon Collins •

    Hi Anonym, please see this factsheet on PEP which answers your questions about testing afterwards:
    https://i-base.info/qa/factsheets/pep-faq

    thanks

  7. Anonym •

    Hi Josh,

    Recently I just received 4th gen test with negative results. This was 42 days after last dose of PEP. Nevertheless, now i experienced diarrhea and urticaria. This could be potentially side effect of SSRI (escitalopramum) which i currently take. Is there still a chance for ARS to appear after 6 weeks from last PEP?

  8. Josh Peasegood •

    Hi Francis, yes the 4th generation test you have done is conclusive. You are HIV negative and no further testing is required.

  9. francis •

    Hello doc,I have taken a both a rapid 3rd gen test and then a 4th gen lab test ab/ag ,8 weeks after pep.Is it conclusive?

  10. Simon Collins •

    Hi Rohit, nothing you describe is a risk for HIV. You didn’t need PEP and you didn’t really need to test. Please see this link for more info:
    https://i-base.info/qa/11844