PrEP — short for pre-exposure prophylaxis — is a medication that HIV-negative people can take to dramatically reduce their risk of getting HIV. When taken consistently, it's one of the most effective HIV prevention tools available. Yet many people who would benefit from it have never heard of it, or aren't sure if it's right for them.
This guide covers the basics: what PrEP is, how it works, the different types available, who should consider it, and how to get a prescription.
How PrEP works
HIV needs to establish itself inside your immune system's CD4 cells to cause infection. PrEP works by maintaining a constant level of antiretroviral medication in your bloodstream and tissues. If you're exposed to HIV — through sex or sharing needles — the drug blocks the virus from replicating before it can take hold.
The key word is pre: the medication needs to be present in your body before exposure. That's why consistent daily use matters. Skipping doses drops drug levels and reduces protection.
Up to 99% effective at preventing HIV from sex when taken as prescribed, according to the CDC. For people who inject drugs, it reduces risk by at least 74%.
Types of PrEP
There are currently three FDA-approved forms of PrEP in the United States.
Daily oral PrEP (Truvada / generic)
Tenofovir disoproxil fumarate / emtricitabine (TDF/FTC), sold under the brand name Truvada and now available as a generic. This is the original PrEP and has the largest evidence base. It's appropriate for adults and adolescents at risk through sex or injection drug use. Full protection for receptive anal sex is reached after about 7 days of consistent dosing; for vaginal sex and injection drug use, allow about 21 days.
Daily oral PrEP (Descovy)
Tenofovir alafenamide / emtricitabine (TAF/FTC), brand name Descovy. A newer formulation that uses a lower dose of tenofovir with a slightly different kidney and bone safety profile, making it a good option for people with kidney concerns. Descovy is only FDA-approved for cisgender men and transgender women who have sex with men — it has not been studied for receptive vaginal sex.
Injectable PrEP (Apretude)
Cabotegravir (CAB-LA), brand name Apretude. An injection given by a healthcare provider — once to start, again one month later, then every two months. No daily pill required. In clinical trials it was shown to be more effective than daily oral PrEP. It's a strong option for people who struggle with daily adherence. Available since 2021 in the US but access varies by location and insurance.
| Type | How taken | Approved for | Effectiveness |
|---|---|---|---|
| Truvada / generic (TDF/FTC) | Daily pill | All adults at risk | Up to 99% |
| Descovy (TAF/FTC) | Daily pill | MSM and trans women | Up to 99% |
| Apretude (CAB-LA) | Injection every 2 months | Adults at risk | Higher than daily pill in trials |
Who should consider PrEP?
PrEP is recommended for HIV-negative people who are at substantial risk of HIV infection. That includes:
- People who have anal or vaginal sex and don't always use condoms, especially with partners of unknown status
- People who have a sexual partner living with HIV
- Gay, bisexual, and other men who have sex with men (MSM) with multiple partners
- People who inject drugs and share equipment
- People who have been prescribed PEP (post-exposure prophylaxis) more than once
- People who have had an STI in the past six months
PrEP is not just for one group. It's prescribed to cisgender men, cisgender women, transgender people, and people of all sexual orientations. If you're sexually active and HIV is a realistic concern for you, it's worth a conversation with your doctor.
What happens while you're on PrEP
PrEP isn't just a prescription you fill once. Staying on it safely means regular check-ins with a healthcare provider:
- HIV test before starting and every 3 months while on PrEP — PrEP must not be taken by someone who is already HIV-positive, as it's not a treatment
- Kidney function test before starting and every 6–12 months
- STI screening every 3 months is standard care alongside PrEP
- Prescription renewal typically requires these check-ins
PrEP does not protect against other STIs. Using condoms alongside PrEP reduces risk further and protects against chlamydia, gonorrhea, syphilis, and other infections.
Side effects
Most people tolerate PrEP well. The most common side effects — nausea, headache, and mild stomach upset — typically appear in the first few weeks and resolve on their own. Serious side effects are rare. TDF-based PrEP (Truvada/generic) has a small effect on kidney function and bone density in some people, which is why regular monitoring matters. TAF-based PrEP (Descovy) has a more favorable profile for kidneys and bones.
How to get PrEP
PrEP requires a prescription from a licensed healthcare provider. Here's how to get started:
- Talk to your doctor or clinic. Many primary care physicians, sexual health clinics, and community health centers prescribe PrEP. If your current provider doesn't, resources like GetYourPrEP.com can help you find one nearby.
- Get an HIV test. You must test HIV-negative before starting. A recent STI panel and kidney function test are also standard.
- Discuss which type is right for you. Daily pill vs. injectable depends on your routine, insurance, and medical history.
- Sort out cost. In the US, most insurance plans (including Medicaid) cover PrEP at no cost. If you're uninsured, manufacturer programs (Gilead Advancing Access) and federal programs like Ready, Set, PrEP offer it free.
Medical disclaimer: This article is for informational purposes only and does not constitute medical advice. PrEP requires a prescription and regular medical monitoring. Talk to a licensed healthcare provider to find out whether PrEP is right for you and which formulation is most appropriate for your situation.