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.

277 comments

  1. James

    Hello – I have received a negative result 6 weeks after completing a course of PEP. The test was a vein test done at a GUM clinic in UK (so I think this would be a 4th generation one, was sent to the lab). Do I need to test again at 12 weeks to be safe?

  2. Josh Peasegood

    Hi Zack, Truvada is used as PrEP. It is not a combination used for PEP. It does contain some of the same medication but PEP uses a combination of 3 drugs, whereas Truvada only contains 2: emtricitabine and tenofovir.

  3. Zack

    And I used only Truvada or Mylan.

    How many percent chance does that stand to work as PeP ?

  4. Josh Peasegood

    Hi Zack, a test after 2 days is not conclusive. The earliest test you can take to be sure is a 4th generation antigen/antibody test. This test will be conclusive 6 weeks after finishing PEP.

  5. Zack

    A test 2days after PeP…..is that a conclusive one ?

  6. Josh Peasegood

    Hi Kitto, yes this test is conclusive. As you have waited 12 weeks after PEP you can consider this test conclusive. You do not have HIV.

  7. Kitto

    12 weeks after pep I did a rapid antibody hiv blood test and came out negative.
    Can I throw this issue aside now?

  8. Josh Peasegood

    Hi Zokay, your test is conclusive. As it has been 6 weeks since you finished your course of PEP, it is confirmatory. You are HIV negative.

  9. Zokay

    6 weeks after Pep I did a 4th generation rapid HIV test in an HIV test center and it was negative. can i close

  10. Josh Peasegood

    Hi Zokay, in the UK a test 6 weeks after PEP is considered conclusive. After 5 weeks it is very likely to remain negative but a follow up test a week later would be able to completely confirm your status.

    0.34 is a vale used to identify HIV. Any number less than 1 means that you do not have HIV. You can follow this link to read more: https://i-base.info/guides/testing/what-does-a-number-on-my-negative-hiv-test-result-mean

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