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 Is the conflicting information I am receiving due to outdated data or current data?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 Santos, TLD is a combination medication containing two of the active ingredients that is used in PEP, Tenofovir and Lamivudine. Starting PEP within 72 hours will offer the best success. Now that you have finished the course you can be tested in 6 weeks. TLD does not often have side effects but can cause poor sleep and mood changes.

  2. Santos

    I commences PEP, about four weeks now and I did had abdominal dreams, and rashes coming out from my face the first I started, week two I had itching almost all my body parts but not from the rash. up till week four I am still seeing rashes coming out from my body. ARV used is TLD 300mg:300mg:50mg

  3. Lisa Thorley

    Hi Erickson,

    There’s no risk, there’s no risk because the woman who you had sex with has an undetectable viral load, please see here: https://i-base.info/u-equals-u/

  4. Erickson

    please help me. I had a protected vaginal sex with an infected woman whose viral load was undetectable. The condom broke and I withdrew immediately I took a home test with her and the result was negative although she had been on treatment for long. Is it true that long term treatment may decrease antibodies to detect hiv on people who are on treatment? I believed that was a false negative. I then had pep in two days and after one week, I experienced sore throat , oral sores, and severe muslce pain. Could this be HIV related or not?


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