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. Jack •

    I had a sore throat before gave a blowjob to unknown guy but I let him ejaculated at my body no in my mouth. I worried about that sore throat it means ulcer at oropharynx so I took PEP at 24 hr after exposed. So, I’m just wondering that sore throat is the risk of HIV exposure or not and today is my 9th day of taking PEP. What do you think about my situation and what should I do next? By the way thank you for your answer tho

  2. Josh Peasegood •

    Hi Anonimous, there is a small chance however the risk s very small. Your partner does not need to take PEP. After PEP you are unsure of your own status. It is recommend to either avoid sex or use condoms before you are able to test.

  3. Anomimous •

    I had unprotected sex immediately after pep, without testing.can I infect someone?

  4. Josh Peasegood •

    Hi Dwayne, you need to wait 6 weeks after PEP. You can test using a 4th generation antigen/antibody test. Before this and the test will not be conclusive.

  5. Dwayne •

    Just finished taking pep
    And haven’t get test
    How should I wait to get test

  6. Simon Collins •

    Hi Zek, you would not have been given PEP in the UK because someone taking effective ART would have an undetectable viral load. Please read more info here:
    https://i-base.info/u-equals-u/

  7. Zek •

    I had unprotected with someone who was on ART for 2 and half months. I started pep 4hrs after exposure and consistently for 28days, tested negative 4wewks after pep, Now in 5th week, Am worried, am I safe?

  8. Simon Collins •

    Hi Selus, all HIV teats will give an accurate result three months after any risk.

  9. Selus •

    I took an HIV antibody test and i tested negative after 3 month i.e this December. The test was immunochromatographic test but I dont know what kind of test.

  10. Simon Collins •

    Hi Cheetah – your HIV test is irrelevant because you were not at any risk. Learning more about HIV and sexual health will stop you worrying in the future.
    https://i-base.info/qa/11844

    It is good for everyone who is sexually active to have a check for HIV and other infection though, so apart form the cost, you have not done any harm. Didn’t anyone at the test clinic tell you this?