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PrEP (Pre-Exposure Prophylaxis)

PrEP (Pre-Exposure Prophylaxis)

Updated on:
August 3, 2021

PrEP is a daily pill to prevent HIV

PrEP is short for pre-exposure prophylaxis. It is a once-per-day HIV prevention pill that reduces the risk of contracting HIV by up to 99%.

If you take a PrEP prescription daily, the presence of the medicine in your bloodstream helps stop HIV from taking hold and spreading in your body. PrEP medication stops HIV in your bloodstream from replicating, eliminating the virus from your body when the original exposure amount dies. Essentially, PrEP works by ensuring HIV cannot replicate in your body and ensures you remain HIV negative.

How does PrEP work to prevent HIV?

PrEP medication stops HIV in your bloodstream from replicating, eliminating the virus from your body when the original exposure amount dies. Essentially, PrEP works by ensuring HIV cannot replicate in your body and ensures you remain HIV negative.

Is PrEP safe?

Usually, less than 10% of patients on PrEP experience any side effects. For those who do experience side effects, they tend to naturally go away within 1-2 weeks. To ensure your body can tolerate PrEP, lab tests are required prior to receiving a prescription.

What is involved with taking PrEP

PrEP is a pill taken orally on a daily basis. Adherence to the daily regimen is important for its effectiveness.

In order to start taking PrEP, lab testing is required before you can get started. Labs are also required after 30 days of being on PrEP, and every three months following that. The tests required are blood and urine tests for HIV, STIs, and to ensure your body can tolerate PrEP.

How effective is daily oral PrEP?

An HIV-negative person can reduce their risk of contracting HIV by 99% when PrEP is taken as prescribed on a daily basis.

PrEP’s effectiveness depends on proper adherence to the daily regimen of taking it.

What is the difference between PEP (Post-Exposure Prophylaxis) vs PrEP?

PEP is short for post-exposure prophylaxis. It is a last-measure HIV prevention method in an HIV-negative person who may have been recently exposed to the virus.

PEP medication must be administered as soon as possible after a potential exposure to HIV. If anyone thinks they may have been exposed to HIV, they should go to an emergency room or sexual health clinic immediately in order to request PEP.

PEP must be started within 72 hours of exposure to HIV. The earliest it is started, the more effective it is. Standard adherence to the full course of PEP drugs should be followed, as well as no additional exposures to HIV.

What is PrEP on-demand?

On-demand PrEP (also referred to as intermittent PrEP) is an alternative HIV prevention medication available for gbMSM folks.

In order for it to be effective, recipients must take two pills two to 24 hours before their first upcoming sexual activity, followed by one pill taken daily until 48 hours after their last sexual activity.

As studies have been solely been conducted with gbMSM, PrEP on-demand is not recommended for people who have vaginal sex or people who inject drugs.

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