Get PrEP & DoxyPEP online
Get Started
Get Started

What is PEP?
(post-exposure prophylaxis)

If you believe you’ve been exposed to HIV, you can only start PEP medication if it’s been less than 72 hours since the potential exposure event. It’s recommended you head to your nearest emergency room as soon as possible if you’re seeking PEP treatment.

PEP 101

PEP is a 28-day course of antiretroviral drugs taken soon after possible exposure to HIV.

PEP must be started within 72 hours after being exposed to HIV to be effective.

Side effects from PEP are usually mild and can be treated with over-the-counter medications.

What is PEP?

Post-exposure prophylaxis (PEP) is a 28-day course of antiretroviral drugs taken soon after possible exposure to HIV. These medications work by preventing seroconversion, which is when somebody who is HIV-negative becomes HIV-positive. To be effective, patients must start the medication regimen within 72 hours of the exposure event.

PEP 101

PEP is a 28-day course of antiretroviral drugs taken soon after possible exposure to HIV.

PEP must be started within 72 hours after being exposed to HIV to be effective.

Side effects from PEP are usually mild and can be treated with over-the-counter medications.

How does PEP work?

For someone to become HIV+, the virus must go through the following steps:


Enter the body


Infect specific immune cells


Use those immune cells to replicate itself


Spread throughout the body and creates ‘reservoirs’

When PEP is taken as prescribed, the HIV drugs in the medication enter the bloodstream. If HIV is present within the body, PEP can block the virus from replicating itself until all the infected cells die; this stops the infection from becoming permanent.

For PEP to work, it’s crucial to take it as soon as possible after a potential exposure and start no later than 72 hours. Proper adherence to the full 28-day regimen helps ensure that high levels of PEP’s anti-HIV drugs are present in the body for the necessary amount of time.

Who should use PEP?

PEP is for anyone who is HIV-negative and may have been exposed to HIV in the last 72 hours (3 days). It’s important to remember that not everyone who is HIV-positive can transmit HIV to their sexual partners.

The most common ways HIV is transmitted are through condomless anal sex, sharing injection equipment, and condomless vaginal sex. If you participated in any of these high-risk activities with someone you believe could transmit HIV, it’s recommended you visit an emergency room as soon as possible.

PEP is not intended for patients that experience HIV exposure risk on an ongoing basis. Those who participate in high-risk behaviours or use PEP multiple times should consider PrEP as an HIV prevention tool.


If the medications were compared to pregnancy prevention tools, PrEP is like birth control, and PEP is like Plan B for HIV.

How effective is PEP?

When taken correctly and within the 72-hour timeframe, PEP is up to 100% effective at preventing chronic HIV infection. However, this decreases over the 72-hour time and with every missed dose of the 28-day regimen. The sooner you start PEP after a possible exposure to HIV, the better.

Patients must take PEP every day for 28 days. During the course, your healthcare provider will conduct HIV and other tests. It is also best practice that PrEP is discussed during this time, as ongoing HIV prevention might be recommended based on future behaviours and risks.

While taking PEP, continue to use other HIV prevention methods. Condoms are an effective way of keeping you and your partner(s) safe. It’s also important to use new, sterile needles when injecting drugs.

HIV prevention is more accessible than ever before
90% of Freddie patients get PrEP + delivery for $0. Book a free virtual consult today to learn more about how you can protect yourself from HIV with PrEP.

How much does PEP cost?

A full-course PEP treatment (28 days) can cost up to $900 or more without coverage.

Coverage for PEP varies across Canada, and not all private and public insurance providers cover the cost.

Patients will see the cost when they fulfill the prescription. If you have supplementary drug insurance through school, work, or the government, you could inquire about the coverage for these drugs.

Common regimens prescribed include:
Dolutegravir combined with generic Truvada (2 tablets)


Biktarvy (1 tablet)

PEP regimens are determined by assessing the patient, prescriber, and insurance coverage.

PEP Side Effects

PEP is very safe, though some users have reported side effects. Potential side effects from PEP include:





Abdominal cramps

Side effects are usually mild and can be treated with over-the-counter medications. Contact your healthcare provider if you experience any side effect that causes extreme discomfort or doesn’t go away.

How to get PEP

PEP is available through emergency rooms, sexual health clinics, and some doctors’ offices. If exposure happens after hours, it’s best to visit the emergency room so that you can start taking PEP as soon as possible.

When visiting the ER or a health clinic, you will be asked about your potential exposure. From there, the doctor will decide if PEP is the best course of action. If approved for PEP, you will also be given a blood test for HIV and tests for Hepatitis B and other STIs.

PEP may not be prescribed if your chance of getting HIV is considered low. Examples of why your risk may be regarded as too low include the following:

The risk of your exposure event:Not all types of exposure are considered equal. For example, oral sex is considered very low risk for HIV transmission.

The likelihood that your partner could transmit HIV:There are other types of protection to consider. For example, your partner may have used a condom, told you they were on PrEP, or were HIV+ but couldn’t transmit.

It’s best to speak with a trained medical professional about your potential HIV exposure to determine if PEP is a fit for your needs.

What happens after I finish PEP?

Follow-up testing is important to make sure that PEP worked. After completing the 28-day PEP regimen, you’ll need to visit your healthcare provider for follow-up testing.

You’ll be tested for HIV 4-6 weeks after your initial exposure and again three months later. Depending on your situation, your provider may recommend you get tested again during the sixth month after your exposure event.

In the meantime, keep protecting yourself and others from HIV by using condoms when you have sex and not sharing drug injection equipment.


How soon can HIV be detected after starting PEP?
Can PEP prevent HIV?
What drugs are used for PEP?
Can I stop PEP?
What happens if I miss one day of PEP?
What causes PEP to fail?
Is PEP hard on the body?
What should I avoid while taking PEP?
What is the best time to take PEP?

Reviewed by:

Dr. Caley Shukalek

Caley is passionate about evidence-based patient-centred care, including telemedicine that can provide high quality care from wherever a patient may choose.

He helped create Alberta’s PrEP guidelines and works as a specialist in General Internal Medicine with additional training in sexual health, including HIV and sexually transmitted infections.

He holds a Masters of Public Health from Johns Hopkins University, an MD from the University of Calgary and an MSc from the University of Alberta.