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Emergency HIV prevention (post-exposure prophylaxis)

PEP, or post-exposure prophylaxis, is emergency treatment to prevent HIV. 

If you think you’ve been exposed to HIV within the last 72 hours you may be able to get PEP. 

It’s a course of treatment that you take for 28 days. 

What is PEP?

PEP is a form of emergency treatment taken after possible exposure to HIV, to prevent HIV infection. 

PEP is different from pre-exposure prophylaxis (PrEP). PrEP is taken before exposure. PEP is taken after exposure and is not for long-term use. 

Who can take PEP?

Anyone who has been at risk of HIV via sex, sharing needles or occupational exposure. It is not for people who have HIV. 

When do you take PEP?

If you think there’s a chance you might have been exposed to HIV, go to a healthcare clinic to ask about PEP right away. 

You must take PEP less than 72 hours after you think you were exposed to HIV. It is most effective if you take it within 24 hours. PEP can’t be taken more than 72 hours after exposure. 

Where can I get PEP?

PEP isn’t available everywhere, so search online to see if you can get it near you. PEP is only available from healthcare clinics or doctors, or sometimes the emergency department of a hospital. 

What happens when you go to get PEP?

Your healthcare provider will want to find out how high your risk of HIV is. They will: 

  • ask about the kind of sex you’ve had 

  • ask about the person you have had sex with to see if they were high risk for having HIV 

  • test you for HIV to check you don’t already have it 

  • explain how to take PEP 

  • tell you when to come back to test for HIV after finishing PEP.

How do you take PEP?

PEP is a combination of pills that you take every day for 4 weeks, at the same time each day. 

Does PEP have side effects?

PEP is safe and not everyone will have side effects. But some people may experience:  

  • nausea  

  • diarrhoea  

  • headaches 

  • tiredness 

  • generally feeling unwell. 

If you experience side effects talk to your healthcare worker. Don’t stop taking PEP, otherwise it may not work. 

When should I test for HIV after taking PEP?

Test for HIV after using PEP, to make sure the treatment was successful. Test three months after the exposure, and again 6 months later. 

What’s involved in HIV testing?

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How does PEP stop HIV?

PEP works by stopping HIV entering cells in the body, which means the virus can’t make copies of itself and spread. This then stops someone from getting HIV. 

How effective is PEP?

PEP isn’t 100% effective. But there have been very few reports of HIV infection after using PEP. 

My partner has HIV. Can I take PEP regularly?

No. If you face a prolonged risk of HIV, for example if your partner is living with HIV or if you regularly have sex without a condom, PrEP is a better choice for you. 


Can I take PEP after sexual assault?

Yes. PEP is often recommended after sexual assault. Deciding if you should take PEP can be difficult, but your healthcare provider will be able to support and advise you about your decision. You don’t have to tell your healthcare provider what happened unless you want to.  

Can I take PEP if I’m pregnant or breastfeeding?

Yes, and it reduces the chance of HIV being passed on to your baby. However, some of the drugs used for PEP aren’t appropriate for pregnant or breastfeeding women. Talk to your healthcare worker for more information. 

Can I take PEP after occupational exposure?

Yes, you might need to take PEP if you accidentally prick yourself with a needle at work for example. If you’re taking PEP after being exposed at work, make sure that you let someone know about your injury. This can help your workplace to implement better precautions for the future. 

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  • Last updated: 06 April 2022
  • Last full review: 01 March 2022
  • Next full review: 01 March 2025
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