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. John

    Hi it’s my third time posting here for help, I exposed myself to HIV on 1st July, took PEP for 30days (only Truvada) “tested negative before starting pep” 4week post PEP, I went for test and the result was negative but was told to retest after 3months which will be early December but i still feel weak in the legs and sometimes in the arms,and it’s 3 days now am having sore throat. Sometimes I feel like unnecessary feelings in the sole of my feet (kinda peripheral neuropathy) have had nosal tension/congestion almost since I started PEP. No rashes, No swollen lymph nodes,No fever,No diarrhea but these other symptoms are getting me so nervous and worried.waiting more 3months feels like hell. Well, waiting with hope and biased causes of the sore throat I am having RN. Used 3rd gen test strip at 4weeks post PEP. What chances do I stand to remain HIV negative? Has anyone ever got these symptoms 4 or more weeks after PEP and remained negative?

  2. Josh Peasegood

    Hi Pascal, your HIV tests are conclusive. The symptoms you are experiencing are not caused by HIV.

  3. Pascal

    I took pep med last June for 30 days all days as I was taking it I develop many symptoms white lesion on my tongue and Strange sign on my tongue and my tonsillitis , pimples in my face after it turns to black many symptoms and august 3,08,23 which is 4 weeks and 3 day I took test. For hiv which came back negative and same august 21 ,that making it 7 weeks after the last pep med dose I took another test 4th generation test which came back negative but after the last test on 21 August 8.23 I develop symptoms in my tonsillitis on right side, before was on left side with pus and I had wound in my tongue which take many time to be healed and my tonsillitis still disturbing me even m tongue , rashes in my face ,, all this symptoms started on 23 .08.23 till today September, I went to another doctor on 4 .09 23 he run normal CDC blood test and every thing came back normal ,only Hämoglobin is 13.5 but before I was reaching 14.7 and now , the doctor decided to do me hiv test again . I am so stressful I don’t know what am doing can pep med delay seroconversion for up to 7 weeks after the last dose , or does the pep med didn’t work ?

  4. Josh Peasegood

    HI Ahmed, a 4th generation test is 95% accurate 4 weeks after an exposure. For a conclusive result this needs to be 6 weeks after an exposure.

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

  5. Ahmed

    Hi, I am posting this query after been struggling with severe anxiety from 47 days.
    I took a 4th Gen ag/ab combo test on 28th & 35th day post exposure, the test came as not reactive 0.1 S/CO for both the tests.

    Do I need to repeat the test, and what are the chances & accuracy for the above mentioned tests.

    Please help me understand once you find time.

  6. Josh Peasegood

    Hi Pascal, using a 4th generation antigen/antibody test 6 weeks after PEP is conclusive. Your symptoms are not caused by HIV or PEP. Please speak with your doctor about other possible causes if these symptoms continue.

  7. Pascal

    Good morning i took a pep meds last June for 30 days and I develop pains instant from 9 days of taking the pep and my doctor told me to wait 6 weeks to be confirm my status , but in all the month I have to wait am having sysptoms all my body and my tongue and my mouth
    Everywhere in my body
    So I couldn,t wait till August 9 , i went to do test on this August 3 but my normal test suppose to be on August 9 and my test on August 3 come back negative
    And I did another test on this August 21 which keep back negative but am still having the symptoms pimples in my forehead and my mouth problem some pains in my head and foot

    Could it be that pep meds is delaying the test for 7 weeks after last pep

  8. Josh Peasegood

    Hi Fiona, after PEP you need to wait at least 6 weeks for your test to be conclusive. For more information please see here: https://i-base.info/qa/factsheets/pep-faq

  9. Fiona

    Hi i tested negative, two days after finishing pep is my status conclusive?

  10. Josh Peasegood

    Hi Agatha, please see here for more information about PEP: https://i-base.info/qa/factsheets/pep-faq

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