What is PrEP? Prescription HIV Prevention 101

What’s the difference between PrEP and PEP? Get the basic run down on PrEP, PEP, and PrEP 2-1-1 to keep you and your sexual partners safe.

February 9, 2022
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This article was updated by the FOLX Editorial Team 9/28/23.

For those of you who don’t know, “PrEP” stands for “pre-exposure prophylaxis.” PrEP is a type of medication taken before possible contact with the Human Immunodeficiency Virus, or as you might know it, HIV. HIV is a virus that can weaken the immune system by attacking certain white blood cells, which are also called CD4, T lymphocyte, or helper cells. 

The most widely known and used method to stop HIV by far is PrEP, a daily pill approved by the FDA. Additionally, there are two other methods that are used as-needed: PrEP 2-1-1 and PEP. You might not have heard of these methods, as they 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), especially to those without health insurance, but, this year, with the expiration of the patent for Truvada, things have started to change. According to the Center for Disease Control and Prevention, in 2021 about 30% of people who could benefit from PrEP were prescribed it, compared to only about 13% in 2017. We are on our way there, but still have a ways to go.

Learn more about PrEP medication and other methods of preventing the risk of getting HIV for you and your sexual partners.

What is PrEP (pre-exposure prophylaxis) in HIV prevention?

PrEP is the most commonly known method to prevent HIV. It’s a daily pill that protects a HIV negative person who may be exposed to HIV from becoming infected with the virus. PrEP is 99% effective—when taken daily—at preventing HIV infection through anal or vaginal sexual activity. PrEP is also 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 both people with penises and people with vaginas when taken daily. However, we don’t have much public health data on exactly how effective PrEP is for folks with neovaginal, colon neovaginal, peritoneal neovaginal, or penile-inversion neovaginal tissues. Studies have found that TDF/FTC as PrEP is safe and effective for transwomen taking estrogen HRT.

Up until recently in the United States, there were two brand name versions of PrEP medication: Truvada and Descovy. 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, which means that the cost is starting to come down. In 2021, the patents expired, and thus the costs of PrEP lowered significantly.

Descovy is only available as a brand name medication, and it’s important to know that Descovy has not been studied for HIV prevention during vaginal sex or with injection drug use.

PrEP is also available as an injection, cabotegravir (CAB), as a bimonthly injection. According to the World Health Organization (WHO), CAB long acting is a long-acting form of PrEP. It is given intramuscularly, with the first two injections administered four weeks apart, followed thereafter by an injection every eight weeks.

Who is eligible for PrEP?

The chances of getting an HIV infection vary depending on the circumstances. In simplest terms: an HIV infection can occur only if one comes into contact with the virus through bodily fluids such as blood, semen, pre-ejaculate, vaginal fluids, rectal fluids, and human milk.  It’s not something that happens spontaneously.

However, some people who are currently HIV negative may be more at risk than others of contracting HIV. 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/STI, 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

Likewise, anyone who has sex with a partner who is positive with a detectable viral load, anyone who has condomless sex with a partner whose status is unknown, and those who share injection drug or tattoo needles are groups with a higher HIV risk than the general population and therefore are eligible for taking PrEP.

In order to avoid contracting HIV, there are three different available prescription treatments— PrEP, PrEP 2-1-1, and PEP.

What are the benefits of PrEP?

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

Does PrEP have side effects?

The side effects of taking PrEP medication can include diarrhea, nausea, headache, fatigue, and stomach pain. Often, these are mild side effects that generally go away after the first month on PrEP. If side effects don't pass, please speak to your health care provider. Taking the pill with a snack or meal at bedtime can help with side effects.

What is the difference between PrEP and PEP?

PrEP 2-1-1, known as “event-based PrEP'' or “on demand” PrEP, is an option for those who have a hard time taking a daily pill and have the power to plan ahead. However, PrEP 2-1-1 has only been shown to be effective for anal sex. PrEP 2-1-1 is named for its dosing:

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

When used correctly, PrEP 2-1-1 can be as effective as daily PrEP. Although the research evidence is not conclusive for transgender women on GAHT/HRT, PrEP 2-1-1 can still be prescribed to transgender women who have anal sex.

What is PEP?

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). It consists of the HIV medications Tenofovir and emtricitabine, intended to be 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 doesn’t replace PrEP or other HIV transmission prevention methods; while PEP can be effective at preventing infection, it’s not 100 percent protective.

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 health care provider's note, but even then, PEP can be unaffordable for the people without health insurance plans (including Medicaid) or access to assistance programs.

Knowing those barriers, the two main options to acquire 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

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.

Are you interested in PrEP (pre-exposure prophylaxis) with FOLX? Check out our sexual health offerings.
For existing FOLX members interested in adding a PrEP medication to their plan, reach out to your clinician through your Athena Patient Portal or reach out to our Member Navigators at the
FOLX Help Center.
For non-FOLX members who want to learn more, read up on all things sexual health in the
FOLX Library.


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