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 Is the conflicting information I am receiving due to outdated data or current data?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. Josh Peasegood

    Hi Mike, there is no reason to be concerned. This is not an exposure to be worried about – if even an exposure at all. Do you have reason to believe this woman was positive? Most people are HIV negative and sex workers are some of the most aware of their own sexual health.

    In the UK this would not have been considered a risk that would require PEP.

    Please follow this link for more information about testing and transmission: https://i-base.info/qa/factsheets/hiv-transmission-and-testing

  2. Mike

    Am mike
    3 weeks ago i had a protected insertive vaginal sex with a sex worker.
    At some point in the motion of in and out, coming out the condom slipped off and remained on her vagina and was still covering my penis head, i removed it and there were no vaginal fluid on me…
    My fear is that when i put another condom my hand (that i used to finger her) slightly touched my penis and had vaginal fluid on it…
    I don’t know her status but i presumed she was positive and started PEP after 12 hours…
    Now i have nasal congestion,…and stressed that PEP might not work…i am on my 21st day on PEP

  3. Josh Peasegood

    Hi Yaqub, for a test to be conclusive it will need to be a rapid test 12 weeks after finishing PEP. Or a 4th generation test 6 weeks after PEP – these are very often used by health clinics.

    Have you spoken to a doctor about your symptoms? Starting PEP as early as you did would allow it to be most effective. Your symptoms of thrush would also not be expected so early on if you were to have HIV. Another factor is that these symptoms can present from being stressed. Have you been able to speak to anyone?

    Please follow this link for more information about testing and transmission:https://i-base.info/qa/factsheets/hiv-transmission-and-testing

  4. Yaqub

    I had an exposure on the 2nd of April 2022 and started PEP 6 hours later.The combination was TLD.3 days into the PEP,I got a white coating on my tongue,which I suspect to be a mild case of thrush.Thereafter,I noticed a clicking sound while swallowing saliva.Muscle ache persisted throughout the course of the drugs and now,48 days after completing the TLD PEP (75 days after exposure),all symptoms are persistig.Had a negative rapid test at 10 weeks.I’m as good as dead due to stress.Please,help me out


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