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 Is the conflicting information I am receiving due to outdated data or current data?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. Simon Collins

    Hi Marvin, if your partner was taking HIV treatment you would not be given PEP in the UK. At this time I would be more worried about coronavirus than HIV.

  2. Marvin

    Hello I base
    I had unprotected sex with a woman who I later found out was hiv positive, we had intercourse on Wednesday and I realized she was positive on Sunday evening, so the doctor prescribed pep for me (efavirenz), but my worry is I think I took pep in the last hour72hour or even past time , I’m currently experiencing runny nose, cough and sneezing it’s my last week of pep, so I would wish to know my chances

  3. Roy Trevelion

    Hi Joseph,

    It’s a good idea to have an HIV test now that it’s over a month since you finished PEP. However, please also see your doctor about all your symptoms, including the rashes.

    You are right to think about starting HIV treatment (ART) sooner rather than later if you are HIV positive. Starting ART can have important benefits to your health.

    Here’s the Introduction to ART. There’s lots of info in this about starting ART. But first please check out your symptoms and have the recommended HIV test.

  4. Joseph

    I was placed on pep after an exposure with an HIV person after 40 hours…the lady told me straight that she is HIV positive and i should start pep(lamivudine and zidovudine).however the lady also used my toothbrush without my permission and she told me after i also used it…now i have finished pep a month ago and im scared to go and test as ive had a lot of HIV positive symptoms…first week on pep it was night sweats,vomiting,loss of appetite,headache,cold hands,stuff nose,muscle pain and flu like symptoms…then after pep i experienced lymph nodes(which is still there now),small rash on penis,two small lines on nails,headaches, bloating,back pain,muscle pain,itching,red and dark spot on hands,teeth feeling cold and lastly i dont cough at all!!!…im scared to go and test after going through all of this but on the other hand i do want to test so that i can start treatment early incase im HIV positive.

  5. Roy Trevelion

    Hi Skakes,

    Please talk to your doctor about your symptoms. You can ask about having another HIV test if you’re worried about seroconversion. But testing usually means you have to wait 4 weeks after PEP for a valid result.

  6. Skakes

    I have just finished PEP yeasterday and im experiencing muscle and back pain even some red spots on my arms and they are very itchy…can this be seroconvetion

  7. Roy Trevelion

    Hi Augustine,

    What does your doctor say about your night sweats? Please talk to them about it and include any other symptoms you may have.

  8. augustine

    its my 6th day of taking pep and i’m sweating extremly at night ,whats the issue ,plz

  9. Roy Trevelion

    Hi Prince,

    Please talk to your doctor about your serious stomach pain. This is not usually reported as a side effect of PEP.

  10. Prince

    Please it been one week am on pep am having serious stomach pain and wait I can’t go to sleep very well I’ve been so weak and I have little appetite to eat please what can I do to reduce all this effect in my body


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