What is PrEP? Prescription HIV Prevention 101

Get the basics on PrEP, PrEP 2-1-1, & PEP to keep it safe.

A pink gradient background with a prescription paper and a bright blue pill.

“PrEP” stands for “pre-exposure prophylaxis,” a type of medication taken before possible contact with HIV (Human Immunodeficiency Virus), a virus that can weaken the immune system by attacking certain white blood cells (also called CD4, T lymphocyte, or helper cells). 

The most widely known and used HIV-preventative method is by far daily PrEP. But there are two other methods that are used as-needed: PrEP 2-1-1 and PEP. These additional methods are less widely prescribed, and have much more narrowly defined windows to be effective. Across all forms of PrEP, cost has been the biggest barrier to access (i.e. $2,000 for a 30-day supply of daily PrEP), but with the recent expiration of the patent for Truvada, things are changing.

First: the chances of getting HIV vary depending on the circumstances.

In simplest terms: an HIV infection can occur only if one comes into contact with the virus. It’s not something spontaneous. Those most at risk for contracting HIV are those who:

  • Have a sexual partner who is HIV positive and has detectable virus in the blood or a partner whose HIV status is unknown
  • Have another sexually transmitted infection, such as gonorrhea (this weakens the lining of internal organs, making it easier for the HIV virus to get through)
  • Use condoms consistently or not at all
  • Share injection equipment with people who may be HIV positive

Although currently there is no available cure for HIV, there are treatments known as anti-retroviral therapy (ART) that lower the amount of HIV virus in the body to an extremely low level. This means that their immune system is able to prevent illness and symptoms, and makes it impossible to pass the infection on to other people. These medicines make it possible to live with HIV and manage it like other chronic conditions, such as diabetes or high blood pressure.

In order to avoid contracting HIV, there are three different available prescription treatments.

Daily PrEP

PrEP is the most commonly known HIV-preventative method. It is a once-daily medication taken orally that protects a person who may be exposed to HIV from becoming infected with the virus. When taken every single day, PrEP is 99% effective at preventing HIV infection through anal or vaginal sexual activity and at least 74% effective when exposed to HIV through injection drug use.

Truvada (generic name emtricitabine-tenofovir disoproxil fumarate or “TDF/FTC,” for short) has been studied and proven effective for people with penises and people with vaginas, when taken daily, however, we don’t have much data on exactly how effective PrEP is for folx with neovaginal, colon neovaginal, peritoneal neovaginal, or penile-inversion neovaginal tissues. A newer study has found that TDF/FTC is safe and effective for folx on HRT.

Descovy has not been studied for prevention during vaginal sex or with injection drug use. 

Up until recently in the US, there were two brand name versions of PrEP: Truvada (TDF/FTC) and Descovy (TAF/FTC). In 2020, there was one generic version of TDF/FTC available in the US, however, only one manufacturer was given the license so their cost wasn’t much lower than the brand name Truvada. Now, more manufacturers are getting the ability to produce generic Truvada, including FOLX partners, meaning the cost is starting to come down. Descovy is only available as a brand name medication. In 2021, the patents will expire, and we expect the costs of PrEP to lower significantly.

If 2 pills are taken the first day, PrEP takes 24 hours to prevent HIV during receptive anal sex (bottoming). If 1 pill is taken the first day, then it takes 7 days of daily use to be protective. For everyone else, it is generally recommended to allow for a full 21 days for PrEP to be fully protective.

PrEP 2-1-1

PrEP 2-1-1, known as “event-based PrEP'' or “on demand” PrEP, is an option for folx who have a hard time taking a pill every day and can plan ahead. PrEP 2-1-1 has only been shown to be effective for anal sex.

PrEP 2-1-1 is named for its dosing:

  • Take 2 pills 2 to 24 hours before sex
  • Take 1 pill in 24 hours and keep taking 1 pill every 24 hours
  • Last pill is taken 48 hours after last episode of sex


High quality research shows that PrEP 2-1-1, when used correctly, can be as effective as daily PrEP. The research evidence is not conclusive for transgender women on HRT, but based on an encouraging recent study, PrEP 2-1-1 is being prescribed to transgender women who have anal sex. 


The emergency option for preventing HIV after a possible exposure is PEP, or Post-Exposure Prophylaxis. PEP is begun within 72-hour after possible exposure to HIV (whether through sex or injection drug use), and consists of the HIV medications Tenofovir and emtricitabine, and they are taken with a third HIV drug, raltegravir or dolutegravir. PEP is taken daily for 28 days, and the sooner it is started, the more effective it is. PEP does not replace PrEP or other HIV transmission prevention methods, and while effective at preventing infection, it’s not 100%.

Access to PEP varies across the country. Unlike in major cities like New York, PEP is not readily available in many hospitals nationwide. Oftentimes, hospitals have a limited amount of PEP that is exhausted within the first few months of of a year, and in some cases, medical professionals are accused of withholding PEP because they belief PEP encourages “unsafe behavior,” or they save PEP for sexual assault victims. In other instances, PEP might only be available at a clinic or doctor’s office, which can be an issue if PEP is needed during a weekend when clinics and offices tend to be closed. Some states are working toward making PEP available over the counter without a doctors note, but even then, PEP can be unaffordable for the people without insurance.

Knowing those barriers, the two main options to get a PEP prescription are:

  1. Find and call a local provider using this HIV.gov locator tool
  2. Contact your local Emergency Room (ER) or urgent care clinic

FOLX is currently able to prescribe daily PrEP with TDF/FTC, and the process begins here. For existing FOLX members interested in adding a PrEP prescription to their plan, reach out to your clinician through your Athena patient portal or reach out to our member advocates at support@folxhealth.com. And for those who want to know more, read up on all things sexual health here, and feel free to reach out to us at support@folxhealth.com.