The medicine
What is PEP?
PEP (post-exposure prophylaxis) is a short course of HIV medicines taken after a possible exposure to HIV. It works by stopping the virus from taking hold in your body.
PEP is an emergency measure. It has to start within 72 hours of the exposure, and the earlier you start, the better it works. You then take it every day for 28 days, without missing doses.
Today’s PEP medicines are generally well tolerated. Some people feel mild nausea or tiredness in the first days, which usually settles. Your doctor explains everything before you start.
PEP at a glance
- When to start As soon as possible. Within 2 hours is ideal, 72 hours is the limit.
- How long Every day for 28 days.
- Who it’s for Anyone with a possible exposure: condom failure, sex without a condom, sexual assault, shared needles or a needle injury.
- Side effects Usually mild, if any.
- Afterwards Follow-up HIV tests confirm you are negative.
The 72-hour window
Like the tide, the window only goes one way
PEP gives the best protection when it starts within hours. After 72 hours it is no longer recommended, so don’t wait for the morning or for the end of your holiday.
0–2 hours
Best time to start
Message us now. We aim to see you straight away.
Day 1
Start today
PEP works well, but every hour counts. Come in today.
Days 2–3
Still possible: urgent
Call us right away so you start before the 72 hours run out.
After 72 hours
Test and get advice
PEP is no longer an option, but HIV testing and advice still matter.
Don’t wait until tomorrow. The sooner PEP starts, the better it works.
Send one message now. A doctor will tell you whether you need PEP and when to come in.