PEP emergency medicines for exposure to HIV

PEP (post-exposure prophylaxis) is a combination of medicines that we give you if you might have been exposed to HIV. The human immunodeficiency virus (HIV) is a virus that damages the cells in your immune system. It weakens your ability to fight everyday infections and disease.

When used together, the medicines can reduce the risk of you getting HIV infection.

You must start treatment within 72 hours (3 days) of possible exposure. After this time, it becomes much less effective. We do not usually recommend starting treatment after 3 days. 

Ideally, you should start the treatment within 24 hours of exposure. 

The aim of the treatment is to prevent you from getting HIV. However, it’s not guaranteed to work.

Tell the doctor or nurse

Please tell the doctor or nurse treating you if you:

  • take any other medicines, including ones you buy (from a pharmacy or shop)
  • are pregnant or think you might be
  • are breastfeeding
  • have any kidney problems
  • have any liver problems
  • have any other medical conditions

Getting your medicines after sexual exposure

You get a 5-day starter pack, but treatment is usually for 4 weeks (28 days) in total. This means you need to come to the sexual health clinic as soon as possible (definitely within 5 days) to get the rest of your medicine.

Call the sexual health triage hotline to arrange an appointment on 020 7188 7707.

You might not need to continue PEP if:

  • the person you had sex with had a negative HIV test in the last 3 months
  • the person you had sex with has HIV and is on treatment
  • the type of sex you had is low risk for getting HIV

Getting your medicines after non-sexual exposure

You get a 28-day starter pack.

You need to see your GP or your occupational health department (if exposure was through your work) for follow-up.

How HIV medicines work

The names of your medicines are:

  • emtricitabine 200mg / tenofovir disoproxil 245mg tablets
  • raltegravir 400mg tablets

These medicines help to stop the HIV virus from reproducing.

Read more about taking your medicines.

Side effects of PEP

Some people have side effects with PEP and others have none at all. If you have any side effects, get medical advice as soon as you can.

Do not stop taking the medicines, unless advised by your doctor.

Read more about side effects of PEP.

Appointments and more tests

During your treatment, you need to have blood tests and appointments. You also have follow-up appointments a few months after you finish your treatment. 

We recommend repeating an HIV test after you finish PEP. 

Find out more about appointments and tests you'll need.

Resource number: 3983
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Contact us

Phone: 020 7188 7707

For medical students on electives abroad:

Contact the occupational health department.

In an emergency, phone 020 7848 6490 or email yea[email protected]

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Do you have any comments or concerns about your care?

Contact our Patient Advice and Liaison Service (PALS)

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