Q and A


Does PEP have side effects?


I am confused with PEP treatment, specifically about the side effects.

From sexual health charities I hear that PEP treatment can cause occasional side effects which may or may not go over the 28 days treatment. Another one (THT) says that the side effects are extreme and about 1 in 5 people on PEP stop taking it as a result.

The sexual health nurse said that side effects on PEP are very common and are severe.

I’ve heard from 3 people who have had PEP and they said that they didn’t get any side effects.

What’s the official line on PEP and side effects? I thought that PEP usually uses recommended triple therapy, using drugs that are well tolerated. Is the conflicting information I am receiving due to outdated data or current data?

Thank you for any clarity you provide.


All meds have some risk of side effects, but for PEP this risk is usually low. If side effects do occur, they are usually mild.

This depends on the meds used in the PEP combination.

In the UK in 2018, the PEP combination is usually raltegravir plus a combined pill with tenofovir DF/emtricitabine, which generally causes very few side effects, if any.

Even general side effects like nausea, diarrhoea and tiredness are not experienced by most people.

If mild side effects occur, they usually get easier after the first week or two as your body adjusts.

PEP that contains a drug called efavirenz is not recommended in the UK, though is used in some countries where there is less choice for HIV drugs. Efavirenz has a higher risk of side effects including mood changes and vivid dreams.

Discontinuation rates for PEP are often not very good. Studies of health workers who are exposed with a needle-stick injury report many people stop before the full month of treatment.

Note: This answer was updated in February 2018 from a question first posted online in June 2009.


  1. Lisa Thorley

    Hi Tesh,

    Access to viral load testing varies depending on where someone lives. Not all people had access to this sort of test. A persons viral load should become undetectable within 1-3 months of starting treatment.

  2. Tesh

    Hi Lisa

    Thank you for your reply to my first comment.

    The reason why I am concerned is that she still didnt get tested for her viral load ever since she started with treatment even though it has been a year and some months this is because she moved to another place or something like that. All she got was her cd4 results when she started which was at 366 or 18.1%.

    So does it mean that it applies to everyone that thier viral load will be undetected after 3 to 6 month of treatment? Since she has taken the treatment for more than those 6 months.

    And regarding the pep treatment, I am already done with the course it has been one week already.

  3. Lisa Thorley

    Hi Tesh,

    Is the women who you had sex with is on treatment and her viral load is undetectable, (it should be because she’s been on med for more than 3 months) there isn’t any risk to you. Please see here: http://i-base.info/u-equals-u/ This means that you don’t need to be on PEP.

  4. Tesh

    I had unprotected sex with someone who is HIV positive but later found out that she has been on treatment for 18 months. I found out the same day and my doctor prescribed me Teevir tablets, which I took within 12 hours after exposure. The next day I went to my local hospital where I got pep treatment of Tenolam and anzavir-R, I took this at 22 hours after the last dose of teevir and in 33 hours after the exposure.

    I took the second dose of pep in 56 hours after exposure. My concern is I never had any side effects during my pep treatment, all I had was a stuffy nose which I still have even though it has been a week after using pep.
    And can the viral load of a person who has Aids be suppressed to undetected levels within six months? Or does this only apply to those who have Hiv and not Aids?

    Please assess my situation and please bare with me as I am just worried.

  5. Roy Trevelion

    Hi Nao,

    I’ll try to answer your questions as numbered:

    1. If your partner was taking HIV treatment and had an undetectable viral load the risk is zero.

    2. The HIV test is what should be used to check if you are HIV positive.

    3. PEP can have the effect of delaying infection.

    4. An HIV test is recommended 4 weeks after finishing PEP because 95% of people produce antibodies to HIV within 4 weeks.

    Please see this link for FAQs for risk and testing.

  6. nao


    Thank you for good help you give us.

    I had protected sex with infected person and I had three open wounds on my hands.in time of removing condom Her vaginal secretions go on my hands open wounds.

    1.how I am risk to HIV positive?

    I took pep in 24hours after exposure(efavirenz, lamivudine and tenofovir). I take it full monthly.i after 1 day of month of pep I tested negative and at five weeks after exposure I had some symptoms like headache, sore throat, swollen lymph glands, night sweat, dry cough, sore and ulcers on my tongue and muscles pain on my neck and sometimes joints pain and also my white tongue.i went to my doctor to look what cause those symptoms, he find that no illness I had. after 6 weeks of exposure( Two weeks ago after pep course) I test again negative.

    2.is that symptoms means that I will be HIV positive???
    3. is pep increasing the window period??
    4.test after month of exposure doesn’t have high meaning from pep who took pep??

    thanks for your help!!!

    I am looking to hearing from you!!

  7. Roy Trevelion

    Hi Sibusiso,

    HIV is difficult to catch. So although you started PEP late you might be HIV negative anyway. It’s recommended that you have another HIV test 4 weeks after finishing PEP to confirm you are negative.

  8. sibusiso

    My doctor put me pep after 9days of exposure with a hivpositiv lady he told mie that despite thatyou must get within 72hoursof exposure it wil help mie now I’m done with course of trivanz but I fel muscles and joints pain is that the side effects of PEP I hav tested hiv negative after 3weeks of exposure what a my chances to prevent hiv


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