PEP
(Information for People who have been exposed to HIV infection)

What is PEP?
PEP stands for Post-Exposure Prophylaxis. It is given to people who have been exposed to HIV infection, in order to reduce the risk of them becoming HIV positive. The most common reason for giving PEP is that someone has had unprotected vaginal or anal sex (without a condom, or where the condom failed) with someone who is known to be HIV positive or is thought likely to be HIV positive.

When can I take PEP?
PEP needs to be started as soon as possible after the sexual exposure, and certainly within 72 hours. PEP is only given after more than 72 hours in exceptional circumstances.

Why would I take PEP?
PEP is taken because it may reduce the risk of HIV transmission. Whether or not to take PEP is a difficult decision. The decision depends largely on estimates of your risk from the sexual exposure.

The following are only guidelines:

For a man having sex with a woman (without condom):
* Vaginal sex with woman known HIV positive Risk about 1 in 1,500
For a woman having sex with a man (without condom)
* Vaginal sex with man known HIV positive Risk about 1 in 500
For a man having sex with a man (without condom)
* Active anal sex with man known HIV positive Risk about 1 in 1,500
* Passive anal sex with man known HIV positive Risk about 1 in 50
* Active anal sex with HIV status not known – estimate unknown
* Passive anal sex with HIV status not known – estimate unknown

NB: The risks are increased if the sex is “traumatic” and bleeding occurs, if either partner has other sexually transmitted infections at the same time, and if the HIV viral load is high.

Does PEP work?
We do not know how effective PEP is at preventing HIV transmission after sexual exposure. PEP has been tested in doctors and nurses exposed to HIV infection through needlestick injuries, and it reduces the risk of transmission by 80% in those cases. We also know that PEP is effective at preventing transmission of HIV from mothers to babies. We therefore expect PEP to be effective at preventing sexual transmission, but we only have limited evidence to back this up. Some people do still become HIV positive even after taking PEP.

What are the drugs?
PEP consists of a combination of anti-HIV drugs. These are the same drugs that have been used for many years for treating people with HIV. The drugs need to be taken every day for four weeks.

There are different combinations which you can discuss with the doctor, and they all consist of several tablets taken once or twice a day. The most common side effects are nausea, diarrhoea and fatigue. The nausea can be treated with anti-sickness medication, and the diarrhoea can also be treated with medication. Some people feel fine when taking PEP, and carry on their lives as normal.

Other people find that they need to take some time off work. About 20-30% of people stop taking PEP because they cannot tolerate the side effects. Serious side effects of PEP are rare, but include liver disturbances and allergic responses to thel drugs.

If I want to take PEP, what will it involve?
You need an HIV test now to make sure that you are not already HIV positive. A health adviser will counsel you about testing for HIV. You also need to see a doctor, who will help you make the decision about hether to take PEP. You will need blood tests today to check your liver and kidney function, and your blood sugar and cholesterol. You will be given 5 days supply of tablets at first.

You will then need to come back and see a doctor, to discuss how you are managing. If you are keen to continue with PEP, you will then be given the rest of the 28 day supply. During this time, you will need to have further blood tests and review by a doctor. You will need HIV tests after three months and six months to see whether or not you have acquired HIV infection.

Is there anything else I need to think about?
You need to think about whether you have caught any other infections. If you are at risk of Hepatitis B infection then you can talk to the doctor about starting vaccines today which protect against Hepatitis B infection. You should also have a screen for sexual transmitted infections two weeks from the sexual exposure.

What about my sexual partners?
At this stage you do not know whether you will become HIV positive. It is sensible to discuss the issues with your sexual partner(s), and to use condoms to protect yourself and to protect them.