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A guide to – PEPSE (Post-exposure prophylaxis for HIV following sexual exposure)


PEPSE – the basics
‘Post-exposure prophylaxis after sexual exposure’ (PEPSE) is a course of medication to prevent infection with HIV after a recent risk of exposure to the virus. In this situation the risk is unprotected sex with someone who is HIV positive or thought possibly to be HIV positive. Unprotected sex means sex without a condom, or sex with a condom which breaks or comes off during sex.

What is HIV?
HIV stands for ‘human immunodeficiency virus.’ HIV is a ‘retrovirus’ which can damage a person’s immune system and put them at risk of a range of serious illnesses. In the 1980s, before HIV was identified, these illnesses were grouped together under the label of the acquired immunodeficiency syndrome (AIDS).

In the UK, few people now develop AIDS conditions because their HIV is controlled by highly effective anti-retroviral treatment (ART). Thanks to ART people with HIV infection can enjoy good health and live a normal lifespan. Unfortunately, ART cannot get rid of HIV from the body and has to be taken for life.  

By far the best policy is to avoid getting infected with HIV. Although PEPSE can be very useful in emergency situations, using condoms during sex is the most effective way of preventing HIV infection.

Do I need to take PEPSE?
If you are HIV negative or have never had an HIV test, you should seek advice if, in the last 72 hours-

* •	You think you may have had come into contact with HIV during unprotected sex, or-
* •	You were sexually assaulted

If you think you need PEPSE ask for help immediately. Do not delay, as every hour counts. It is important for you to know that PEPSE is not always needed after unprotected sex. Health professionals use the British Association for Sexual Health and HIV (BASHH) guidelines to decide who needs to take PEPSE.

Where can I get PEPSE?
You can get PEPSE from departments of genitourinary medicine (GUM) or sexually transmitted infection (STI) clinics. It is important that you tell the clinic staff that you think you may need PEPSE. They will make sure that you are seen as soon as possible. If the GUM clinic is closed you should go to your nearest Accident and Emergency (A+E) department. Large A+E units are open 24/7.

How soon should I start PEPSE?
As soon as possible, because the sooner the treatment is taken, the better it works. PEPSE can offer protection if it is started up to 72 hours after a risk has happened.

How long do I need to take PEPSE?
PEPSE needs to be taken for 28 days. It is important to take the full course of treatment to get the full benefit from it.

What medicines are in PEPSE?
PEPSE in the UK is usually a combination of a pink tablet containing raltegravir (marketed as Isentress®) and a blue tablet called Truvada®. Each Truvada tablet contains two medicines: tenofovir and emtricitabine. Some countries use different ART as PEPSE. In certain situations, your doctor may give you treatment other than raltegravir and Truvada.

How do I take PEPSE? 
You should take one raltegravir tablet and one Truvada tablet as soon as you are given them. After these first doses, you should take the medicines as follows:

* •	Raltegravir (pink) one tablet every 12 hours (i.e. twice a day)  
* •	Truvada (blue) one tablet every 24 hours (i.e. once a day)

Does PEPSE have any side effects?
PEPSE is safe and most people who take it will have no side effects. However, like all medicines, raltegravir and Truvada can sometimes cause unwanted symptoms. Commonly reported problems (up to 1 in 10 patients) include feeling sick, a lack of energy, dizziness, diarrhoea (loose or watery bowel motions), loss of appetite, trouble sleeping, headache and stomach ache. If any of these problems happen they are usually mild and don’t last very long. However, if the side effects are causing a big problem for you, or making it difficult for you to carry on taking PEPSE you should phone the sexual health clinic and ask for advice.
If you get a skin rash or flu-like illness while taking PEPSE this might be because you have developed an allergic reaction to the medication. However, the same symptoms sometimes happen after HIV infection. 
So if you develop a skin rash or a flu-like illness while taking PEPSE or in the 12 weeks after you stop taking PEPSE, you should contact the clinic as soon as possible. 

What tests do I need?
It is important to have an HIV test before you start taking PEPSE to make sure you are not already infected. Tests to check your liver and kidneys are done because PEPSE can cause liver or kidney damage, although this is rare. You may be advised to have tests for sexually transmitted infections (STI) such as chlamydia, gonorrhoea and syphilis. Some clinics advise you to wait a few days before having your STI check. The clinic may offer you a course of injections to protect you from infection of your liver with hepatitis B virus which, like HIV, can be caught during sex.

Does PEPSE work?
The risk of catching HIV from a single sex act is very small. However, research shows that becoming infected with HIV is less likely if you take PEPSE. PEPSE does not work every time and some people may be infected with HIV despite taking PEPSE. PEPSE is less likely to work if you miss tablets or if you don’t complete the full 28 day course.


What do I do if I forget to take PEPSE?
Less than 24 hours late: 
you should take the missed dose immediately and then take the next dose at the normal time. 
24–48 hours late: 
don’t take the dose(s) you have missed. Wait till your next dose would have been due and then start to take your PEPSE again 
as normal.

More than 48 hours late: 
stop taking PEPSE.

Can I take PEPSE if I am pregnant?
Yes. ARVs like raltegravir and Truvada are taken by HIV positive women in their pregnancies. If you are pregnant or breastfeeding, please tell the doctor. She or he will discuss the benefits and risks of PEPSE with you.

What should I do if I am taking other medication?
It is very important to tell the doctor about any other medication you are taking. This includes over-the-counter medicines and herbal preparations. The doctor can then check that these won’t stop your PEPSE from working. Some indigestion treatments and vitamin tablets can interfere with PEPSE. So in the 28 days when you are taking PEPSE you should check with the doctor before taking any other kind of medicine, tablet or herbal preparation.

Can I have sex while taking PEPSE?
We advise you to have protected sex (with a condom) until you have been told by your clinic doctor that it is safe not to use condoms. The final HIV test usually happens no earlier than 4 weeks after you finish taking PEPSE. You can ask for free condoms within the clinic. You should not share razors or toothbrushes with other people until you have been given the 
all clear.

Who can support me through this time?
Doctors, nurses and health advisers in the sexual health clinic are there to support you. They can also put you in touch with voluntary agencies and charities in the community. If you feel able to talk to friends or family during this time you may find it very helpful.

What happens after I finish PEPSE?
The clinic will advise you to have an HIV test 4–8 weeks after you finish PEPSE. You may also be advised to test for syphilis and hepatitis C infection at the same time.


This leaflet was produced by the Clinical Effectiveness Group of the British Association for Sexual Health and HIV (BASHH). Its contents are based on the BASHH ‘UK guideline for the use of HIV Post-Exposure Prophylaxis Following Sexual Exposure, 2015.’
More information: 
BASHH: www.bashh.org/guidelinesTerence Higgins Trust: 
www.tht.org.ukQuestions about PEPSE? 
Contact your nearest sexual health clinic.


Copyright BASHH 2018. This leaflet was first published January 2018. Revision date January 2021.Comments on this leaflet? Contact us at admin@BASHH.org. 
Please type ‘PEPSE PIL’ in the subject box of your e-mail.