What is PEP?
Post Exposure Prophylaxis, or PEP, is a course of HIV medication which you can take if you have been at risk of HIV infection. The course of medication lasts 28 days and, if you start taking it within 72 hours of being at risk, it may be able to prevent you from becoming infected with HIV. In other words, it is a form of protection (against HIV) that you can take after you have taken a risk or had a condom break.

Where do I get PEP?

• At a Sexual Health Clinic

• At an Accident & Emergency (A&E) department of some hospitals -  A&Es are especially important at weekends because most Sexual Health Clinics will not be open

• Because HIV medication is expensive, clinics will only prescribe PEP if they believe that you have had a real chance of infection

• PEP will not be given to someone who is already HIV-positive so you will always be tested for HIV before you are put on the course.

How effective is PEP?
Research indicates that PEP can prevent infection with HIV, but it is not 100% effective [1]. PEP is more likely to be effective when the treatment starts as soon as possible after the risk occurred. It will not be prescribed later than 72 hours after HIV exposure.

What are the side effects?
People taking PEP are likely to experience the same kind of side effects as HIV-positive people experience when they begin to take HIV medication, which can include:

• Diarrhoea

• nausea

• headaches

• tiredness.

As a result of these side effects, some people fail to complete the full course of PEP.

How do I get PEP 
If you believe that you need PEP you must act fast. The sooner you start PEP, the more likely it is to be effective. If you put yourself at risk at the weekend, do not wait until Monday to act. Try to contact your local sexual health clinic first and ask to speak to a sexual health nurse or health adviser urgently. If this isn't possible, explain that you think you've been exposed to HIV and want to access PEP. Ask for the names of whoever you speak to and write them down – this could speed things up when you go to the clinic later. If you cannot find an open clinic, go to a hospital’s Accident & Emergency (A&E) department.

What do I do at a clinic or A&E department?
Go to the reception and explain you want to see someone urgently about PEP to prevent HIV infection. If you have already spoken to someone on the phone, give their name. If you haven't, tell them you need to see someone as soon as possible, and be determined. Don't agree to come back later. You must start PEP within 72 hours of putting yourself at risk of HIV at the latest. If you are at the A&E department of your local hospital it may help to ask them to call the 'on-duty HIV registrar' who will have experience in PEP and HIV.

What do I tell the doctor? 
When you get to speak to a doctor or nurse, tell them you want PEP and give details of when and how you were at risk of HIV infection. If the doctor you are speaking to is unfamiliar with PEP, refer them to the British Association for Sexual Health and HIV (BASHH) guidelines for PEP after sexual exposure (PEPSE) to HIV [2].

What questions will I have to answer?
There will be a number of questions to answer so that the doctor can decide if you need PEP. It is important to provide honest answers. You will be asked about the following:

• When you think you were at risk

• The sex you had (e.g. oral, anal, involving semen, using a condom)

• The person you had sex with (to try and determine if they were HIV positive)

 If you know that your partner was HIV-positive it may be easier for you to get PEP if you let the doctor know or if your partner is willing to go to the clinic or hospital with you.

What medication will they use?
PEP consists of a triple combination of anti-HIV drugs [3]. A number of different drugs/tablets might be used. The drugs should be taken as prescribed, usually for 28 days.

Taking PEP
The drugs used for PEP are expensive and powerful so the decision to offer treatment is not taken lightly. PEP uses the same drugs that treat HIV infection so you are likely to experience the same kind of side effects as people who are beginning to take HIV medication. Common side effects include diarrhoea, nausea, headaches, and tiredness. In rare cases more serious side effects, such as liver damage, can occur. The doctor will need to explain the effects of these medications before you start PEP. Some people often stop taking PEP or miss doses due to these side effects, but this stops the treatment from working. In order to have the greatest chance of success, every dose of PEP must be taken as prescribed. If you find you have missed a dose, take it as soon as you remember it.