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PrEP for HIV: All about Pre-Exposure Prophylaxis

Dr. Patrick Carroll, MD

Medically reviewed by Patrick Carroll, MD

Written by Our Editorial Team

Last updated 9/09/2020

Today, it’s estimated 1.1 million people in the U.S. have HIV, according to the Centers for Disease Control and Prevention. And while treatments for the virus are better than they’ve ever been, medical prevention is also now possible. 

PrEP or pre-exposure prophylaxis is medication you can take to prevent HIV infection. It’s available with a doctor’s prescription and has provided peace of mind to countless at-risk adults. 

But before you begin any prescription drug regimen, it’s important to get all of the facts. 

TL;DR What You Need to Know About PrEP

  • PrEP is medication designed to prevent HIV infection. 

  • PrEP is currently offered under the brand names Truvada® and Descovy®. 

  • A generic version of Truvada is expected to become available sometime in the next year. 

  • PrEP — both with Truvada and Descovy — is up to 99 percent effective at preventing HIV transmission through sex. 

  • The drug reaches maximum effectiveness after taking it for seven to 20 days, depending on the activity you’re engaged in (sex vs. IV drug use, for example). 

  • PrEP is appropriate for people at an elevated risk of contracting HIV. 

  • PrEP is a daily pill that must be taken consistently. Missing or skipping doses increases your risk of HIV. 

  • The state of California recently passed a law which will allow Truvada and Descovy to be dispensed by a pharmacist starting January 01, 2020 without a prescription, making it the first state in the country to do so.

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HIV/AIDS and PrEP History

HIV/AIDS changed the world, beginning in the 1980s when cases of the new disease began bulldozing the LGBTQ communities across the U.S. 

As time passed and scientists began to understand the condition, they learned more about how it spread, at-risk populations and how best to medically treat people who were carrying the virus or infected with AIDS.   

One revelation in the understanding of HIV/AIDS was that it isn’t a condition that only affects gay men and transgender women — it can affect anyone. In fact, it’s believed the misconception that only gay men were at risk led to cases among other high risk populations to grow. 

In the mid-1980s, scientists began developing drugs to treat HIV and AIDS, called antiretrovirals. But HIV prevention mainly centered on encouraging safer sex and drug use among those at risk. 

Truvada — a brand name drug made of two antiretroviral medications, tenofovir disoproxil fumarate and emtricitabine — was approved in 2004 by the Food and Drug Administration (FDA) for use in the treatment of HIV. Eight years later, in 2012 and after proving itself effective as a preventive medicine, it was approved by the FDA as an HIV preventative

It was the only pre-exposure prophylaxis (PrEP) currently available in the U.S. until October 2019, when the FDA approved a new PrEP medication called Descovy.

How Does PrEP Work?

Truvada for PrEP® is a combination of two drugs — tenofovir disoproxil fumarate and emtricitabine. These two drugs are antiretrovirals, originally approved to treat HIV infection. It wasn’t until 2012 that the FDA approved them for use in HIV prevention. 

Descovy works similarly to Truvada, but it uses a newer form of tenofovir called tenofovir alafenamide. 

Though Descovy is a new drug, it appears to be slightly more effective at HIV suppression and poses less risk of adverse renal and bone events. However, it should also be noted that Descovy is not approved for people at risk of contracting HIV through receptive vaginal sex because it has not yet been clinically tested in those groups. 

PrEP works to lower your risk of contracting HIV. By taking the drug consistently every day, you maintain levels of it in your bloodstream. There, the medications block HIV from taking hold and spreading throughout your body.

However, in order to be effective, PrEP must be taken consistently, every single day. Missing a dose or taking it late can significantly affect its ability to prevent HIV. 

How Long Before PrEP Is Effective? 

Once you begin taking PrEP, you must take it every day. How long it takes to become effective depends on the activity you’re engaging in:

  • For receptive anal sex, Truvada reaches maximum effectiveness at seven days.

  • For receptive vaginal sex, Truvada reaches maximum effectiveness at 20 days. 

  • For IV drug use, Truvada reaches maximum effectiveness at 20 days. 

For all other risk enhancing uses — “insertive” vaginal and anal sex, for example — no clear data is available on maximum effectiveness, according to the CDC. To be safe and ensure maximum prevention, always use a condom whether you’re taking PrEP or not. 

How Effective Is PrEP in Preventing HIV? 

When taken as directed (consistently, every day!), Truvada can reduce your risk of contracting HIV through sex by 99 percent. For those hoping to prevent transmission while using IV drug use, PrEP can be 74 percent effective. 

Thus far, clinical research on Descovy has shown it’s equally (if not slightly more) effective at preventing HIV transmission through sex as Truvada.

PrEP effectiveness depends on consistency, so don’t forget to take it daily.

Is PrEP Right For Me?

PrEP is appropriate for many different people, especially those at a high risk of contracting HIV. Appropriate groups include

  • Homosexual and bisexual men and transgender women who have sex with men

  • Men and women who don’t consistently use condoms 

  • People who have sex with HIV positive partners 

  • People who frequently contract sexually transmitted diseases (STDs)

  • People with multiple sexual partners and/or partners with an unknown HIV status

  • IV drug users

However, if you’re opting for Descovy over Truvada, it’s important to remember that Descovy is not indicated for people engaging in receptive vaginal sex.

How Can I Get PrEP?

As of January 01, 2020, PrEP will be available for purchase without prescription in the state of California, thanks to a new bill signed into law by California Governor Gavin Newsom. 

Senate Bill 159 authorizes pharmacists to issue 30- and 60-day supplies of PrEP without need for a prescription.

In the other 49 states, however, PrEP is available only by prescription, so you must talk to a healthcare provider if you’re considering it outside California.

They may ask about your sexual practices to determine whether you’re a good candidate for PrEP. 

They’ll also likely require an HIV test to ensure you’re currently HIV-negative. It’s important that you’re tested regularly for HIV, even while on PrEP. 

Your doctor will likely ask you to return every three months for those follow-up tests and to ensure you’re tolerating the drug. 

To learn more, read our article on how to get PrEP online.

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How Much Does PrEP Cost? 

Just how much you’ll pay for PrEP depends on whether you have prescription drug coverage on a health insurance policy. If so, you’ll likely a copay or coinsurance obligation that will vary from policy to policy. Your best bet in receiving a cost estimate is to contact your pharmacy and ask. 

If you’re uninsured, both Truvada and Descovy can be very expensive. Depending on where you purchase your medication, Truvada can cost upwards of $2,000 for a 30-day supply. Descovy appears to be slightly less expensive, with reports indicating it can cost around $1,850 for a 30-day supply.

In either case, the drugs’ manufacturer, Gilead, offers financial assistance for those who qualify. See their website for more details. 

A generic version of Truvada for PrEP is expected to be available sometime this year, and it’s likely the price will be less for the generic. 

This article is for informational purposes only and does not constitute medical advice. The information contained herein is not a substitute for and should never be relied upon for professional medical advice. Always talk to your doctor about the risks and benefits of any treatment. Learn more about our editorial standards here.