What is Pre-exposure prophylaxis?

Updated on October 22, 2021

Pre-exposure prophylaxis, better known as PrEP, is a course of medication taken by people with negative HIV status to protect themselves against the virus.

PrEP is not the same as PEP. PEP stands for post-exposure prophylaxis, and it is an emergency treatment for HIV that you take after possible exposure to the virus.

How does PrEP Work Against HIV?

Our bodies have no natural means of fighting and getting rid of HIV. This is because the virus targets your immune system directly, aiming for a specific type of white blood cell. White blood cells are cells in the immune system which shield the body from infection and disease.

HIV specifically attacks white blood cells known as CD4 cells. CD4 cells help to coordinate your body’s immune system response, organizing protection against attacks by harmful invaders. However, HIV tricks your CD4 cells into becoming a safe space for the virus, allowing it to reproduce and spread throughout your body.

If you’re exposed to HIV, PrEP can prevent the virus from setting up shop in your body and prevent it from spreading. It does this by setting up fortifications around CD4 cells. These fortifications prevent HIV from spreading to healthy cells and reproducing. It also keeps HIV from gaining access to CD4 cells.

PrEP involves taking one of two pills. Both pills contain tenofovir and emtricitabine and are approved for daily use in people who are at risk of HIV transmission. The brand names for these pills are Truvada and Descovy. Coverage for PrEP for HIV in Canada depends on the province. For example, in Quebec, Truvada and Descovy are covered under the province’s medical plan, but not in Manitoba.

Who Should Take PrEP?

PrEP is designed for people who are HIV-negative, but due to their lifestyle, are more at risk of contracting an HIV infection. It can be used by both men and women, regardless of whether they are cis or transgender.

You should take PrEP if you meet any of the following criteria:

  • Your sexual partner is living with HIV and has a detectable viral load.
  • You’re a gay or bisexual man with multiple sexual partners, and you don’t always use condoms.
  • You have sex for money or receive gifts for sex.
  • You have sexual relations with persons of the opposite sex without a condom and whose HIV status is unknown to you. Still, they are at high risk of HIV infection (for example, they habitually inject drugs or have multiple or bisexual male partners).
  • You’re a gay or bisexual man in a new sexual relationship, and you are not yet aware of your partner’s HIV status, and you don’t always use condoms.

PrEP prevents HIV infection during both anal and vaginal sex, but there are different recommendations for how you should take it, depending on your gender and the sex you have.

How Do You Take PrEP?

There are two ways that you can take PrEP:

One Tablet Per Day

This is recommended for women who are both trans and cis-gendered as well as transgender men that have vaginal/frontal sex, men who have anal or vaginal sex with women, and gay and bisexual men.

You will need to take PrEP for seven days before you are protected. You will then need to keep taking it for however long you require protection.


If you can plan for sex at least two hours in advance or delay sex for at least two hours and you are a gay or bisexual man, then this option is for you. However, you should note that different types of event-based PrEP depend on your pattern of sexual activity. Therefore you must talk through your options with a health professional.

When Can You Start PrEP, and How Long Do You Have to Take it For?

Before starting PrEP, you need to take an HIV test to ensure that you don’t already have HIV. If you already have the virus, taking PrEP may increase your chances of developing drug resistance, making HIV treatment less effective.

When you have HIV, you must take the treatment for life. However, most people don’t need to stay on PrEP for the entirety of their lives. Instead, PrEP is typically taken for periods of weeks, months or years, when a person feels they’re at risk for HIV. For example, they might take it during a specific relationship or when planning a holiday where they know they’ll be sexually active with new people whose status they won’t know.

Where Can You Get PrEP?

As of this writing, PrEp is not available everywhere, and even in places where it is available, it can be hard to get. However, international guidelines now recommend that PrEP be made widely available. This means that it may be available globally in the near future.

If you want to get PrEP, you should contact a healthcare professional. They will be able to offer advice, support, and monitoring to help you take PrEP correctly and make sure you’re completely protected.

Additionally, there are dedicated websites that can help you purchase PrEP. However, you should make sure these sites offer medical professional oversight.

The Editorial Team at Healthcare Business Today is made up of skilled healthcare writers and experts, led by our managing editor, Daniel Casciato, who has over 25 years of experience in healthcare writing. Since 1998, we have produced compelling and informative content for numerous publications, establishing ourselves as a trusted resource for health and wellness information. We offer readers access to fresh health, medicine, science, and technology developments and the latest in patient news, emphasizing how these developments affect our lives.