Information for patients - PEP /PEPSE

Cork Emergency Departments


This leaflet has been written to give you some basic information about Post Exposure Prophylaxis (PEP) for HIV.

What is HIV?

Human Immunodeficiency Virus (HIV) is a virus that attacks the immune system. Although it is a treatable infection, once infected you have the infection for life. It can be passed on by exposure to infected blood or other infected body fluids e.g. semen. We test for HIV by doing a blood test. Print version.

If I have been exposed to HIV, what is the chance that I will become infected with HIV?

This is very difficult to answer and depends on:

  1. the type of exposure
  2. the chance the source/person is HIV positive

Overall the risk of infection is low, but certain exposures may carry a higher risk of infection. Even if you have had definite exposure to HIV, this does NOT mean that you will definitely get infected. e.g. the risk of HIV transmission following a needle stick injury from a known HIV positive person is approximated at about 3 infections per 1000 people exposed. PEP further reduces this risk. Print version.

What is Post Exposure Prophylaxis (PEP)?

PEP is the term we use for taking “anti- HIV” medication to reduce your chances of becoming infected with HIV. It is only useful in certain circumstances. It has been shown to prevent most (but not all) people becoming infected with HIV. The tablets work best if taken immediately after the exposure. There is no strong evidence for its use beyond 72 hours post exposure.

What does PEP treatment involve?

Your doctor will decide what “anti HIV” tablets you should take and will give you clear instructions on how to take them. You may be seen directly by a specialist who will explain this to you. Or you may be issued a “7 day starter pack” from the Emergency Department containing enough PEP until you are seen by a specialist. You should NOT run out of medication. Usually PEP is taken for a 28 day course and then stopped. During this time you will be seen for regular blood tests to check for side effects. Once you have finished your PEP you will get further appointments for follow up blood tests to check for HIV and other blood borne infections.

Part of the assessment and follow up care is to offer protection against Hepatitis B, and advice regarding Hepatitis C and general sexual health.

What happens if I am Pregnant?

You can still take PEP if you are pregnant, but you must tell the doctor if you are pregnant or think you are pregnant, as the HIV drugs that you are offered may be different. Print version.

What if I am taking other medication?

There is a possibility that other medication may affect or be affected by PEP. It is very important to tell the Doctor if you are taking other medication (including “over the counter” and “herbal” medicines). They will check if these are ok to take with PEP.

Potential side effects:

  • Fatigue
  • Nausea / vomiting
  • Diarrhoea
  • Feeling bloated / abdominal cramps
  • Difficulty sleeping
  • Abnormal liver blood tests
  • Abnormal kidney blood tests
  • Skin rash

If you suffer from any of these side effects you should tell the doctor who might be able to offer treatment to help.

What do I do if I miss a dose?

Take the missed dose immediately, and then take the next dose at the normal time. If you don’t remember until the next dose is almost due don’t take extra doses, just carry on as normal.

Who will look after me whilst I am taking PEP?

Once you have started taking PEP you will be seen either by your Occupational Health Department or local HIV specialist. They will monitor you while you are taking PEP, arrange your blood tests, and offer support. The service, including medication, is free of charge. Print version.

Dr Arthur Jackson (Consultant Infectious Diseases), Dr Íomhar O' Sullivan, Consultants in Emergency Medicine. Last review Dr IOS 11/04/23.