Pre-exposure Prophylaxis (PrEP)

Pre-exposure prophylaxis (PrEP) is a type of daily medication taken by HIV-negative individuals who are at high risk of being infected by HIV. Pre-exposure means before coming into contact, and prophylaxis stands for preventative treatment.1

PrEP works through a series of biological pathways. A healthy individual has a substantial amount of immune system T-cells in their body. These cells target and destroy bacteria, viruses, or other organisms that can come in and do harm to the human body.  An HIV-infected person, however, has a lower number of T-cells because the HIV virus attacks and takes over these cells in order to replicate itself. From this process, more HIV viruses are created and dispersed throughout the body, leading to infection and eventually disease. Fortunately, PrEP builds a protective shield around healthy T-cells to prevent HIV from taking hostage of them. This prevents the virus from replicating, effectively depleting the amount of HIV to avoid infection and disease. PrEP operates best when taken as a daily medication, so that in the event the individual does come in contact with HIV, PrEP can do its job most effectively. PrEP is not a cure for HIV, but a preventative measure. Furthermore, PrEP only protects against HIV, and not other sexually-transmitted infections.1


People Suited for PrEP

PrEP is not the most suitable drug for everyone. It is best suited for those who are HIV-negative, sexually active, or in a relationship.2

  • Those who are HIV-negative and in a relationship with an HIV-positive partner
  • Those who are not monogamous and want to have sexual intercourse with multiple people
  • HIV-negative gay or bisexual men who have been engaging in anal intercourse without a condom or other forms of contraception
  • HIV-negative heterosexual men and women who have sexual intercourse without a condom or other forms of contraception
  • Any HIV-negative individual whose partner is at high risk of HIV, such as someone whose partner injects drugs or a woman with a bisexual partner

These are some of the main examples of individuals who would benefit most from PrEP.



Truvuda is currently the only drug on the market for PrEP. As such, all statistics related to the effectiveness of PrEP will be linked to Truvuda specifically.

PrEP is a very effective drug, and leads to a 92-99% reduction in HIV infection for HIV-negative individuals. PrEP is at its most effective when taken on a daily basis. For example, those who take PrEP seven days per week have a 99% level of protection, yet those who take PrEP only four days per week have a 96% level of protection. When those who take PrEP two days per week only have a 76% level of protection. This data suggest that PrEP will prevent HIV infection most appropriately when taken daily. The effectiveness of PrEP increases even more when combined with other contraceptive techniques, such as the male condom, female condom, and other types of barrier methods.

Additionally, one must take PrEP for at least seven days before it reaches peak levels of effectiveness. Furthermore, if one chooses to stop taking PrEP, they should still take PrEP daily for four more weeks following the last potential exposure to HIV.2


Side Effects

Truvuda, the PrEP drug, is generally very safe and has not been shown to lead to any long-term health consequences. However, there are still some downsides to taking PrEP daily, as it can cause some unpleasant side effects. According to information collected from clinical trials, 9% of individuals experienced nausea, 4.5% of individuals experienced headaches, and 2.2% of individuals experienced unexplained weight loss. However, these side effects subsided after several weeks on PrEP. Discontinuing PrEP also stopped these side effects. It is absolutely crucial to discuss possible side effects with a physician before deciding to take PrEP.2



PrEP can cost anywhere between $0 to $2000 per month. It is imperative to discuss payment options with one’s health insurance company prior to committing to taking PrEP.


Concluding Remarks

HIV can be a life-threatening sexually-transmitted infection. Luckily, PrEP is a very safe and effective preventative measure that can be taken by HIV-negative individuals prior to contact with HIV. It is recommended to take PrEP on a daily basis and in combination with other forms of contraception to increase its effectiveness. Some people report experiencing unpleasant side effects when taking PrEP, but these usually subside after taking PrEP for several weeks, or discontinuing PrEP altogether. These side effects should be discussed with a physician prior to taking PrEP. The cost of PrEP should also be considered by talking with a health insurance consultant, as well as communicating with one’s partner and family before making the decision to take PrEP.1



1. Centers for Disease Control and Prevention

2. PrEP, PrEP Facts, 1 Nov. 2018

Last Updated 28 November 2018.