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If you’re at a higher risk of catching HIV, you may have heard the terms PrEP or PEP. These medicines can help reduce your chances of catching HIV.

HIV infection rates have been declining in recent years, but the epidemic isn’t gone. At the end of 2022, the World Health Organization (WHO) reported that about 39 million people worldwide were living with HIV. According to the Centers for Disease Control and Prevention (CDC), 1.2 million of them live in the United States.

Fortunately, advancements in prevention have made it possible to reduce your risk of getting HIV. One popular but sometimes misunderstood option for infection prevention is pre-exposure prophylaxis, sometimes called PrEP.

What Is PrEP?

Prophylaxis is a medical term for prevention. PrEP refers to medication regimens that help prevent infection with HIV. PrEP medication is an important tool in the ongoing battle against HIV and AIDS.

According to the CDC, PrEP is up to 99% effective in preventing HIV infection when used correctly. It has reduced transmission rates in communities at high risk for HIV infection, such as men who have sex with men (MSM).

How Does PrEP Prevent HIV Infection?

In the United States, three types of PrEP medication are available. Their brand names are Truvada^®, Descovy^®, and Apretude^®.

Truvada and Descovy are oral pills. Both work by entering the immune cells in which HIV is present.

Apretude is an injection that works by blocking an enzyme that HIV needs to replicate. To start Apretude, patients need two injections one month apart. After this first series, they’ll receive additional shots once every two months.

Each PrEP medication has its strengths and weaknesses. Descovy is not yet approved for at-risk people who receive vaginal penetrative sex. Apretude isn’t appropriate for intravenous (IV) drug users.

Truvada and Descovy users must remember to take their medicine every day. The Apretude injection is less frequent but requires a visit to a health care provider every two months.

Can I Still Get HIV on PrEP? (and Other Common Questions)

When used correctly, PrEP is up to 99% effective in preventing HIV infection. But it’s still possible to contract the virus while taking PrEP medication. Imperfect use of PrEP reduces its effectiveness: If you miss a dose, your infection risk increases.

Your risk of getting HIV also depends on how you’re exposed to the virus while taking PrEP. For example, CDC studies show that PrEP is only about 74% effective for people at risk for infection through IV drug use. For couples who practice anal sex, the risk is higher for the receiving partner (the “bottom”) than the inserting one (the “top”). There is also some indication that PrEP can be less effective when people have multiple sexual partners.

Certain behaviors, such as oral sex, carry a very low risk of infection. However, if you engage in these behaviors many times without protective measures, your lifetime risk of infection increases.

Can I get HIV after just one exposure?

Although it’s rare, it’s also possible to contract HIV after just one exposure. For example, the CDC estimates the following risks for a single sexual encounter:

• An HIV-negative person receives unprotected anal sex from an HIV-positive person: one in 72 chance of infection.
• An HIV-negative person receives unprotected vaginal sex from an HIV-positive person: one in 1,250 chance of infection.

Though a person can get exposed to HIV without catching it, the virus can cause significant health problems if you do catch it. It still isn’t worth gambling with these odds.

Can I have HIV without knowing it?

You can have HIV without knowing it for years, even decades. During this time, you may unwittingly spread the virus to your sexual partners. According to the CDC, almost one in five Americans who have HIV aren’t aware they have it.

A systematic review and meta-analysis from 2023 found that, on average, three years pass before a newly infected person receives an HIV diagnosis. This underscores the importance of regular HIV testing.

Should I Use Other Prevention Measures with PrEP?

Major health organizations in most countries recommend PrEP for people at high risk of HIV infection.

These include:

• Female sex workers.
• IV drug users.
• Men who have sex with men.
• People who have sex with HIV-positive people with detectable levels of virus in their bloodstreams.

PrEP may not minimize risk in all cases. Because its effectiveness depends on near-perfect use, at-risk people may wish to use other protection methods.

Condoms can reduce the risk of HIV transmission during penetrative sex by about 85% when used correctly, according to the National Institute of Allergy and Infectious Diseases. PrEP alone is safer than condoms alone, but together, they dramatically decrease your risk of catching HIV.

And, unlike PrEP, condoms also help protect against other sexually transmitted infections, such as gonorrhea. IV drug users can reduce their risk by not reusing or sharing needles with others.

How Do I Access and Use PrEP Medication?

Many at-risk people are willing to use PrEP to prevent HIV infection. However, they’re unsure how to find and pay for PrEP medication. Fortunately, resources abound to help people access PrEP.

If you have a health care provider, visit them and ask for PrEP. Before prescribing any type of PrEP medication, they’ll need to test you for an existing HIV infection. Starting PrEP during the early stages of an unknown HIV infection can cause drug resistance and reduce the drug’s effectiveness.

People who don’t have a health care provider can use PrEPLocator.org to search the CDC’s database for a nearby provider.

Most insurance programs, including Medicaid, cover PrEP. For those who don’t have prescription drug coverage, the government’s Ready, Set, PrEP program helps applicants get Truvada and Descovy for free. Other programs like ViiVConnect can help people who take Apretude pay for their shots.

Regardless of how you access PrEP, you should congratulate yourself! You’re taking an important step to protect your health and the health of others in your community.