PEP (post-exposure prophylaxis)
10-minute read
Key facts
- Post-exposure prophylaxis (PEP) is when you take medicine to prevent HIV infection after being exposed to the virus.
- You must start taking PEP within 72 hours of exposure to HIV — the earlier you start PEP the better.
- Taking PEP can help your immune system to stop the virus from replicating (multiplying) in your body.
- Some people have mild to moderate side effects from PEP, such as nausea, vomiting and headaches.
- Speak to your doctor or sexual health clinic if you have any questions about PEP while you're taking it.
What is PEP (post-exposure prophylaxis)?
Post-exposure prophylaxis (PEP) is when you take medicine to prevent HIV infection after being exposed to the virus. The PEP medicine is the same medicine that HIV-positive people use to reduce the impact of HIV on their body.
Untreated HIV infection usually leads to acquired immunodeficiency syndrome (AIDS).
PEP uses short-term antiretroviral therapy (ART) in HIV-negative people who may have been exposed to HIV. This exposure can happen through:
- unprotected sexual activity (sex without condoms)
- sharing needles or syringes
- a needlestick injury if you are a healthcare worker
PEP is not guaranteed to prevent HIV. It should be thought of as a last option in HIV prevention. It is not a substitute for other HIV prevention methods.
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What are the most common reasons for needing PEP?
It's always best to check with a doctor about whether you need PEP after an exposure, and what other treatments you may need.
The table below shows some activities after which you may need PEP.
| HIV exposure | PEP required? |
|---|---|
| Male to male sex — with someone whose HIV status is unknown or who is HIV-positive and either not on treatment or has a high viral load | Yes |
| Sharing needles (with an HIV-positive person, or where HIV status is unknown) | Yes |
| Sex with someone on PrEP | No |
| Sex with someone with HIV who has a non-detectable viral load | No |
| Community needle stick injury | No |
There have been no reported cases of HIV after community needlestick injuries. This is when you get a needlestick injury from a discarded needle in a public place. You do not need to take PEP in this situation. However, you should see a doctor within 72 hours to:
- talk about getting a hepatitis B vaccination
- get a test for hepatitis C
How does PEP work?
You must start taking PEP within 72 hours of possible exposure to HIV. The earlier you start PEP, the better. Ideally, this would be within 24 hours of exposure.
It takes a few days for HIV to become established in your body. Taking PEP may help your immune system stop the virus from replicating (multiplying) in your body.
The cells that were originally infected with HIV will then die naturally without making more copies of HIV.
How well does PEP work?
PEP generally works well if you:
- take it early
- take it as prescribed — every day for a month
- avoid further exposure to HIV
However, some people have become HIV-positive after taking PEP.
Reasons for PEP not working can be:
- if you don't take it as prescribed
- that some PEP medicines don't work against some strains of HIV — although this is rare
- that the viral load (the amount of HIV) in your body was too great for the medicine to work
The sooner you start PEP treatment, the more likely it is to work.
What types of medicines might I be prescribed?
Most people who take PEP will get a single tablet that contains 2 medicines — tenofovir disoproxil and emtricitabine. Some people need a third medicine, dolutegravir.
If you're pregnant or breastfeeding, your doctor may recommend a different medicine.
While you're taking PEP you should:
- have safe sex
- use contraception to stop pregnancy
- practice safe injecting behaviours
What are the side effects or risks of PEP?
Some people may have side effects such as:
These side effects are usually only mild to moderate. They're usually worse in the first week of taking PEP and get better with time. Any side effects will stop once you finish your course of PEP.
Some people will have no side effects on PEP.
If you feel that you can't tolerate the side effects, talk to the doctor who prescribed your PEP. They may be able to change the type of PEP medicines you're taking. Other medicines may have fewer side effects.
How do I get PEP?
PEP is available from:
- emergency departments in most public hospitals
- sexual health clinics
- some clinics and doctors specialising in HIV and gay men's health
If you plan to visit a clinic or doctor, call ahead and check that they're open.
If you're exposed to HIV outside of regular office hours, go to the nearest hospital emergency department. This will help you start PEP promptly.
Find out where you can get PEP near you.
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What will my doctor ask me?
When you ask for PEP, your doctor or nurse will ask you why you think you've been exposed to HIV. This may be from having sex without a condom, the condom breaking or from sharing injecting equipment.
They will ask if you know whether you may have been exposed to someone who:
- has HIV
- has HIV but has an undetectable viral load
- has HIV but is on treatment
If you've been exposed to HIV through sex, your doctor will ask about the kind of sex you had.
It's important to be honest when answering these questions. The information you provide will help them to work out whether you need PEP.
How much does PEP cost?
PEP is usually free from:
- hospital emergency departments
- HIV and sexual health clinics
- hospital pharmacies
The cost of PEP from a community pharmacy can vary. And not all community pharmacies can give you PEP immediately.
When should I see my doctor for follow up?
Speak to your doctor or sexual health clinic if you have any questions about PEP while you're taking it.
You should be tested for HIV after 6 weeks and 12 weeks of taking PEP.
A test at week 6 can show very early HIV infection. If you get a positive result, you can start HIV treatment straight away.
A negative result at week 6 does not mean that you don't have HIV. This is because you're still in the window period.
If your week 12 HIV test is negative, your follow-up is complete.
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Are there any alternatives to this medicine?
Pre-exposure prophylaxis (PrEP) is an antiviral medicine. You can take PrEP if you don't have HIV and want to lower your chance of catching HIV. PrEP lowers your chance of getting HIV by up to 99%.
When you finish your PEP course, you may want to start on PrEP. This is a good idea if you're likely to keep being exposed to HIV.
PrEP is taken daily to help prevent HIV infection before exposure. Any doctor in Australia can prescribe PrEP.
Resources and support
Visit the GET PEP website to learn more about PEP and how it works.
To talk with someone about whether you need PEP and where you can get it call:
- New South Wales PEP Hotline on 1800 737 669 (1800 PEP NOW)
- Queensland PEP Information on 13 43 25 84 (13 HEALTH)
- South Australia PEP Hotline on 1800 022 226
- Tasmania Sexual Health Service on 1800 675 859
- Victoria PEP Phoneline on 1800 889 887
- Western Australia PEP Line on 1300 767 161
If there's no phone line for your state or territory, or you're calling outside of staffed hours, please go to your nearest hospital emergency department.
You can also call the healthdirect helpline on 1800 022 222 (known as NURSE-ON-CALL in Victoria). A registered nurse is available to speak with 24 hours a day, 7 days a week.
The Multicultural HIV and Hepatitis Service has information on HIV, PEP and PrEP in languages other than English.