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.

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:


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

What medication will they use?
PEP consists of a triple combination of anti-HIV drugs [3]. A number of different drugs may be used, but the recommended combination is Truvada (one tablet taken once daily) and Ritonavir (one tablet twice daily). Truvada is a combination pill consisting of tenofovir (TDF) and emtricitabine (FTC). The drugs should be taken as prescribed 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.

Where do I get PEP?

This will vary from country to country, the following applies to the UK.

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.

Category: Do I have HIV or need to test?

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