PrEP and PEP

What is PrEP?

PrEP means Pre-Exposure Prophylaxis, and it’s the use of anti-HIV medications to keep HIV negative people from becoming infected. PrEP is approved by the FDA and has been shown to be safe and effective at preventing HIV infection.


Even though PrEP has been around in the U.S. since 2012, a lot of people still are looking to learn about it. And, even fewer people feel like they know enough about it to be able to make an informed decision about whether or not to use it. For people using PrEP, you can’t really feel or see PrEP working when you use it- so it can help to have a mental picture of what is happening each time you take a dose.

This video was made to provide an illustration of HIV infection and how PrEP generally works to prevent it, and why “once a day” dosing is recommended.


Talk to a provider or go to one of the websites listed here to learn more.

Learn More About PrEP

  • - PrEP information page (

  • AIDSinfoNet - Reliable, Up-To-Date Treatment Information (

  • AVAC - Global Advocacy for HIV Prevention (

  • Avert - AVERTing HIV and AIDS (

  • CDC - Questions and Answers from the U.S Centers for Disease Control and Prevention (

  • PrEP4Love - The PrEP4Love campaign is brought to you with love by members of the Chicago PrEP Working Group (

  • PrEP Facts - San Francisco AIDS Foundation PrEP information in visual format for MSM and heterosexual individuals, with an option for Spanish (

  • PrEP Locator - An interactive website that helps people locate PrEP providers (

  • PrEP Watch - Interactive webpage with information and resources on gaining access to PrEP (

  • PrEParing for HIV - An Epidemic Interventions Initiative by the University of California

  • Project Inform - Videos, publications and resources (

  • SFHIV - City and County of San Francisco Department of Public Health’s PrEP information page (


  • Talk PrEP - AIDS Action Committee’s new PrEP campaign encouraging everyone to Do It Daily (


Guidance for Use of PrEP in Practice and Research Settings

WHO - World Health Organization (
See newest guidance at


CDC - Downloadable PDF from the Centers for Disease Control and Prevention (
See newest guidance at


From the Makers of Truvada - Information about Truvada for PrEP for healthcare providers, consumers and educators - Downloadable forms and resources for PrEP prescribers and users - Questions and Answers about Truvada for PrEP


PEP (Post-Exposure Prophylaxis) is a month-long course of drugs to help prevent HIV infection that is taken after a possible exposure to HIV.

The sooner someone starts PEP the better. It is most effective when started within 24 hours, but it must be started within 72 hours after a possible exposure to HIV.

The PEP drugs are the same drugs that HIV-positive people use to reduce its impact on their body.

PEP is short for Post-Exposure Prophylaxis.

Post = after
Exposure = a situation where HIV enters someone’s body (e.g., during sex without a condom or by sharing needles or injecting equipment)
Prophylaxis = prevention of disease

PEP isn’t guaranteed to work but does in the majority of cases.


PEP stands for Post-Exposure Prophylaxis and is the focus of this website.
It is a month-long course of drugs to help prevent HIV infection that is taken after a possible exposure to HIV.

PrEP stands for Pre-Exposure Prophylaxis.
It is a drug taken daily over a sustained period to help prevent HIV infection before exposure.
More information about PrEP can be found here.


  • Sex without a condom with a person who has, or might have, HIV

  • Condom breaking or slipping off during sex

  • Sharing needles or syringes with a person who has, or might have, HIV


The sooner PEP is started after exposure to HIV the better. It is most effective when started within 24 hours, but it needs to be started within 72 hours. The longer you wait, the greater the chance that PEP won’t work. PEP usually isn’t given more than 72 hours (3 days) after exposure as studies show it is unlikely to be effective.

However, if you are unable to access PEP within the 72 hours, even if it has been up to 5-7 days since the exposure occurred, it is still worth seeking medical advice to see what your options are. This may include commencing a 3-drug combination of antiretroviral medications as soon as possible just in case you have become HIV positive. In this case, you would be starting very early treatment and minimising the damage to your immune system.


There is no cure for HIV once it has established itself in the body. However, if taken within 72 hours (3 days) of exposure to HIV, PEP can, in most cases, prevent it from establishing itself in the body.



  • Taking PEP may prevent you from becoming HIV positive.

  • You only need to take PEP for a month (28 days). If you become HIV positive you may have to take anti-HIV treatments for a lifetime.


  • Some people may experience some side-effects such as nausea and headaches, though some people will experience no side-effects.

  • You have to remember to take PEP at regular times of the day for a month.


Some states and territories also have PEP information lines if you want to talk to someone about your risk and if you would be recommended to take PEP, as well as up-to-date locations of where to get PEP.