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HIV Prevention

PrEP: The Complete Guide
to HIV Prevention Medication

Pre-exposure prophylaxis (PrEP) is one of the most powerful HIV prevention tools ever developed. When taken consistently, it reduces the risk of getting HIV from sex by up to 99%. Here is everything you need to know.

Prevention FDA Approved Evidence-Based
This page is educational and based on guidance from the CDC, FDA, and HHS. It is not a substitute for medical advice. Talk to a healthcare provider about whether PrEP is right for you.
99% Reduction in HIV risk from sex
CDC, 2023
74% Reduction from injection drug use
CDC, 2023
1.2M+ Americans on PrEP in 2023
CDC HIV Surveillance, 2023
3 FDA-approved PrEP options
FDA, 2024
Understanding PrEP

What Is PrEP?

Pre-exposure prophylaxis (PrEP) is a daily medication, or long-acting injectable, taken by HIV-negative people to prevent HIV infection. When taken as prescribed, PrEP is highly effective because the drugs reach high enough levels in the bloodstream and tissues to block HIV from establishing a permanent infection.

PrEP is not the same as treatment for HIV. It is specifically for people who do not have HIV but are at substantial risk of getting it. If you already have HIV, you need HIV treatment, not PrEP.

How It Works

PrEP works by keeping HIV from replicating inside the body. The antiviral drugs in PrEP interfere with reverse transcriptase, an enzyme HIV needs to copy itself. If HIV enters the body, the medication prevents it from making copies and spreading. For this to work, adequate drug levels must already be present in your blood and tissues before exposure.

PrEP is recommended by the CDC, the World Health Organization (WHO), the U.S. Preventive Services Task Force (USPSTF), and every major infectious disease medical organization. It is a cornerstone of the federal Ending the HIV Epidemic in the U.S. (EHE) initiative, which aims to reduce new HIV infections by 90% by 2030.

Candidacy

Who Should Consider PrEP?

PrEP is recommended for HIV-negative adults and adolescents who are at substantial risk for HIV infection. "Substantial risk" is defined broadly and includes many people in the LGBTQ+ community. You may be a good candidate for PrEP if any of the following apply to you.

Gay and Bisexual Men (MSM)

  • Have a partner with HIV, especially if their viral load is unknown
  • Had anal sex without condoms in the past 6 months
  • Have had a bacterial STI (syphilis, gonorrhea, chlamydia) in the past 6 months
  • Have multiple or anonymous sexual partners
  • Use apps or other means to meet partners whose HIV status is unknown

Transgender and Non-Binary People

  • Trans women who have receptive anal sex with male partners
  • Trans men who have anal sex or vaginal sex with male partners
  • Any trans or non-binary person with a partner living with HIV
  • Anyone who has had a bacterial STI in the past 6 months
  • Trans people engaged in sex work

People in Serodifferent Relationships

  • If your partner has HIV and is not on treatment, or has a detectable viral load
  • During conception attempts with an HIV-positive partner
  • If there is any uncertainty about your partner's adherence to their HIV treatment
  • While waiting for your partner's viral load to become undetectable

People Who Inject Drugs

  • Share needles, syringes, or other injection equipment
  • Have an injection partner with HIV
  • Have been in drug treatment programs but continue using
  • Use stimulants (crystal meth, cocaine) in sexual contexts
Important Note

You do not need to fit a specific profile to ask your doctor about PrEP. If you feel you are at risk, you have the right to ask. CDC guidelines say providers should offer PrEP to anyone who requests it and is HIV-negative. A good healthcare provider will not judge you for asking.

Your Options

The Three FDA-Approved PrEP Medications

As of 2024, the FDA has approved three PrEP medications. They are equally effective at preventing HIV when used correctly, but differ in form, dosing schedule, approvals, and considerations for different bodies. Talk to your provider about which is the best fit for you.

Truvada
Emtricitabine / Tenofovir DF (TDF)
ScheduleOne pill taken once daily
FDA Approved ForAll adults and adolescents at risk from sex or injection drug use. Generic versions available since 2020, significantly lowering cost.
Time to Full Protection7 days for receptive anal sex; 21 days for receptive vaginal sex and injection drug use
Key ConsiderationCan affect kidney function and bone density in some people. Requires creatinine and kidney function monitoring.
Daily Oral Pill
Descovy
Emtricitabine / Tenofovir AF (TAF)
ScheduleOne pill taken once daily
FDA Approved ForAdults and adolescents (over 35 kg) at risk from sex, excluding those with receptive vaginal sex. Not approved for people assigned female at birth with penis-in-vagina sex.
Time to Full Protection7 days for receptive anal sex
Key ConsiderationGentler on kidneys and bones than Truvada, making it preferred for people with kidney disease or osteoporosis. No generic available; may be more expensive.
Daily Oral Pill
Apretude
Cabotegravir (CAB-LA) Injectable
ScheduleTwo starter injections (4 weeks apart), then one injection every 8 weeks
FDA Approved ForAdults and adolescents (at least 35 kg) at risk from sexual exposure. First long-acting injectable PrEP. Approved December 2021.
Time to Full ProtectionAfter the first injection (at day 1) and second injection (at week 4), protection is established
Key ConsiderationIdeal for people who have difficulty with daily pill adherence. Requires clinic visits every 8 weeks. Drug resistance risk if injections are significantly delayed. Not yet available at every clinic.
Injection Every 8 Weeks
A Note on PrEP for Trans People

Studies on PrEP effectiveness for trans women found that Truvada was highly effective when taken consistently, with drug levels in rectal tissue (relevant for receptive anal sex) reaching protective levels. Research on Descovy for trans women who have receptive vaginal sex with male partners is more limited, which is why it is not FDA-approved for that indication. Cabotegravir (Apretude) is approved for all at-risk adults regardless of gender identity. Hormone therapy does not affect how PrEP works in your body. Always share your full medication list with your provider, as some HIV medications used in PrEP may interact with feminizing or masculinizing hormones at the pharmacological level, though no interactions with standard HRT doses have been found to reduce PrEP efficacy.

Getting Started

How to Get PrEP: Step by Step

  1. Get an HIV Test

    PrEP can only be prescribed to people who are HIV-negative. Your provider will test you for HIV before prescribing, and again every 3 months while you are on PrEP. This is a safety requirement because taking PrEP while HIV-positive can cause the virus to develop drug resistance. A rapid test gives results in 20 minutes.

  2. Find a PrEP Provider

    Many providers can prescribe PrEP including primary care doctors, infectious disease specialists, sexual health clinics, community health centers, and LGBTQ+ health centers. Use the federal PrEP Locator at preplocator.org to find a prescribing provider near you, including free and low-cost options. Planned Parenthood locations also offer PrEP.

  3. Have a Conversation About Which PrEP Is Right for You

    Tell your provider about your sexual practices, your partners, any medications you take (including hormones), and your preferences for a daily pill versus injections. There is no wrong answer. Your comfort and ability to stick with the regimen matters most for PrEP to work.

  4. Complete Your Baseline Labs

    Before starting PrEP, your provider will run: an HIV test, a kidney function test (creatinine/eGFR), Hepatitis B screening (Truvada and Descovy contain tenofovir, which also treats Hepatitis B, so your status matters), an STI screen, and possibly a Hepatitis C test. Results typically come back within a few days.

  5. Fill Your Prescription and Start

    Most pharmacies can fill a PrEP prescription. If cost is a concern, do not skip this step before reading the cost assistance section below. Programs exist to cover PrEP at no cost, even without insurance. Starting PrEP is the most important thing you can do.

  6. Follow-Up Every 3 Months

    While on PrEP, you will need a check-in every 3 months for an HIV test, STI screening, kidney function labs, and a medication refill. These appointments are critical for your safety and typically take about 15 minutes. Some providers offer telehealth follow-ups with home test kits to make this easier.

Cost Assistance

How to Get PrEP for Free or Low Cost

PrEP is expensive at retail price, often $2,000 or more per month without assistance. But multiple programs exist specifically to make PrEP free or affordable for anyone who needs it, regardless of income, insurance status, or immigration status.

Ready, Set, PrEP

A federal government program operated by the U.S. Department of Health and Human Services (HHS) that provides PrEP medication at no cost to uninsured or underinsured Americans. Covers both Truvada and Descovy. Eligibility requires a negative HIV test and no insurance coverage for prescription drugs.

How to Enroll: Call 1-855-447-8410 or visit getyourprep.com. A prescription is required. This program does not cover labs or clinic visits.

Program: Federal HHS / Administered by Pharmacy

Gilead Advancing Access (Truvada / Descovy)

Gilead Sciences, the manufacturer of Truvada and Descovy, offers a patient assistance program for uninsured or underinsured individuals. Can cover the full cost of medication. Also offers a co-pay card for insured patients that reduces co-pays to $0. Income requirements apply for the full assistance program.

How to Enroll: Visit gileadadvancingaccess.com or call 1-800-226-2056.

Program: Manufacturer Patient Assistance

ViiV Healthcare (Apretude / Cabotegravir)

ViiV Healthcare, the manufacturer of Apretude, offers the ViiV Connect patient assistance program. Can provide Apretude at no cost to eligible uninsured patients. Also offers support for insured patients with high out-of-pocket costs. Insurance navigation support is available through their program coordinators.

How to Enroll: Visit viivhealthcare.com or call 1-844-588-3288.

Program: Manufacturer Patient Assistance

Community Health Centers (FQHCs)

Federally Qualified Health Centers provide PrEP on a sliding-scale fee based on income, and many offer it completely free to those who qualify. Labs and clinic visits are also included in the sliding scale. They serve patients regardless of insurance, immigration status, or ability to pay.

How to Find One: Visit findahealthcenter.hrsa.gov and enter your zip code.

Program: Federal HRSA Funding

Generic Truvada (Cost-Effective Option)

Generic versions of Truvada (emtricitabine/tenofovir DF) have been available since 2020. Generic PrEP at major pharmacy chains often costs $30 to $60 per month with a GoodRx coupon, making it accessible even without programs or insurance for many people. Descovy and Apretude do not yet have generics.

How to Save: Ask for the generic by name. Use GoodRx.com or NeedyMeds.org to compare prices at pharmacies near you.

Generic Drug Pricing

Local LGBTQ+ Health Centers

Many LGBTQ+-specific health centers offer PrEP navigation services: help applying for assistance programs, same-day testing and prescription, and labs covered separately from medication costs. Services and funding vary by organization. Organizations like Callen-Lorde (NYC), Howard Brown (Chicago), and Fenway Health (Boston) are examples of comprehensive models.

How to Find One: Use the QueerLine local resource finder for LGBTQ+ health centers in your zip code.

Local LGBTQ+ Health Organizations
The Affordable Care Act and PrEP

A landmark 2019 U.S. Preventive Services Task Force (USPSTF) recommendation gave PrEP an "A" rating, meaning most private insurance plans and Medicaid programs are required to cover PrEP with no cost sharing (no copays, no deductibles) under the Affordable Care Act. If you have insurance and are paying out of pocket for PrEP, contact your insurer and ask about PrEP coverage. If they refuse, contact your state insurance commissioner. Note: as of 2024, this coverage mandate is subject to ongoing legal challenges; check current status at hiv.gov.

Safety

Side Effects and Safety

PrEP is considered very safe for most people. Most side effects, when they occur, are mild and go away within the first few weeks of starting treatment. Serious side effects are rare but monitored through the required quarterly lab tests.

Common Side Effects (Usually Temporary)

  • Nausea (most common in the first 2 to 4 weeks)
  • Headache
  • Fatigue or feeling tired
  • Diarrhea or stomach discomfort
  • Decreased appetite
  • Injection site reactions (Apretude only): soreness, redness, or swelling at injection site

Less Common, Worth Monitoring

  • Small decreases in kidney function (Truvada more than Descovy): monitored with quarterly creatinine test
  • Small decreases in bone mineral density (Truvada): usually clinically insignificant; consider calcium and vitamin D
  • Hepatitis B flare if Truvada or Descovy is stopped abruptly in someone with Hepatitis B: always tell your doctor before stopping
  • Mood changes (rare, reported with Apretude): contact provider if you experience depression or mood shifts
Important: Never Stop PrEP Abruptly Without Talking to Your Provider

If you take Truvada or Descovy and have Hepatitis B, stopping suddenly can cause a Hepatitis B flare, which can be serious. Always talk to your provider before stopping. If you stop PrEP for any reason, HIV protection ends within days to weeks (depending on which drug you use and how your body metabolizes it). If you need to stop, discuss a safe transition plan with your provider.

Frequently Asked Questions

PrEP Questions, Answered

Does PrEP protect against STIs other than HIV?

No. PrEP only prevents HIV. It does not protect against gonorrhea, chlamydia, syphilis, herpes, HPV, or other sexually transmitted infections. Regular STI testing every 3 months (required while on PrEP anyway) and using condoms are still important for your overall sexual health.

Does PrEP work if I miss a dose?

Missing occasional doses reduces protection. The level of reduction depends on the drug and your body weight. For Truvada, studies suggest that 4 out of 7 doses per week provides substantial (though not maximum) protection for receptive anal sex. For receptive vaginal sex, more consistent daily dosing is needed. For Apretude injections, protection drops significantly if you are more than 7 days late for a scheduled injection. The bottom line: take every dose as prescribed for maximum protection.

Can I take PrEP only when I think I'll need it? (On-demand PrEP)

A dosing strategy called "on-demand" or "2-1-1" PrEP has been studied for cisgender men who have sex with men. It involves taking 2 pills 2 to 24 hours before sex, then 1 pill 24 hours after the first dose, and 1 more pill 48 hours after the first dose. This was studied with Truvada and showed high efficacy in two large trials (IPERGAY, PREVENIR). However, this approach is NOT FDA-approved, has not been studied in trans women or anyone engaging in vaginal sex, and is not recommended by CDC guidelines. Discuss it with your provider if daily dosing is challenging for you.

I am already undetectable on HIV treatment. Can my partner still take PrEP?

U=U (Undetectable equals Untransmittable) is real and scientifically validated: a person with HIV who is consistently virally undetectable cannot transmit HIV sexually. Your partner may choose to take PrEP for additional peace of mind, and that is a completely valid personal choice. Whether to use PrEP alongside U=U is a discussion for couples to have with a shared healthcare provider. Both approaches are effective, and using both provides maximum certainty.

Will my doctor judge me for asking about PrEP?

They should not. PrEP is a medically recommended prevention tool endorsed by the CDC. If your current provider dismisses PrEP conversations, refuses to prescribe it without medical justification, or makes you feel judged, seek a different provider who is experienced in LGBTQ+ health. LGBTQ+ health centers and sexual health clinics routinely prescribe PrEP without judgment. You deserve affirming care.

Does PrEP affect fertility or pregnancy?

PrEP does not affect fertility. For cisgender women or trans men with a uterus who become pregnant while on PrEP (or who plan to conceive), Truvada (not Descovy) can be continued through pregnancy and breastfeeding if the provider determines the benefit outweighs the risk. The Truvada Pregnancy Registry has not found harm to infants born to people on Truvada. Cabotegravir (Apretude) should be discontinued before pregnancy due to insufficient safety data. Discuss your specific situation with your OB or a maternal-fetal medicine specialist.

What is PEP and how is it different from PrEP?

PEP (post-exposure prophylaxis) is emergency HIV treatment taken after a potential HIV exposure. Unlike PrEP, which is ongoing prevention, PEP must be started within 72 hours of exposure and taken for 28 days. PEP is not a substitute for PrEP if you are regularly at risk. If you think you have had a recent HIV exposure, go to an emergency room, urgent care, or sexual health clinic immediately and ask for PEP. Do not wait.

Next Steps
Sources and References
  • Centers for Disease Control and Prevention (CDC). Pre-Exposure Prophylaxis (PrEP). cdc.gov/hiv/risk/prep/ (2023)
  • U.S. Food and Drug Administration (FDA). FDA-Approved PrEP Medications. fda.gov (2024)
  • U.S. Department of Health and Human Services (HHS). Ready, Set, PrEP Program. getyourprep.com (2024)
  • Grant RM, et al. Preexposure Chemoprophylaxis for HIV Prevention in Men Who Have Sex with Men. N Engl J Med. 2010;363:2587-2599. (iPrEx Trial)
  • Molina JM, et al. On-Demand Preexposure Prophylaxis in Men at High Risk for HIV-1 Infection. N Engl J Med. 2015;373:2237-2246. (IPERGAY Trial)
  • U.S. Preventive Services Task Force (USPSTF). Pre-Exposure Prophylaxis for the Prevention of HIV Infection. JAMA. 2019;321(22):2203-2213.
  • Gilead Sciences. Advancing Access Patient Assistance Program. gileadadvancingaccess.com (2024)
  • ViiV Healthcare. ViiV Connect Patient Support. viivhealthcare.com (2024)
  • Landovitz RJ, et al. Cabotegravir versus Tenofovir Disoproxil Fumarate for HIV Prevention. N Engl J Med. 2021;385:595-608. (HPTN 083 Trial)
  • HRSA. Find a Health Center. findahealthcenter.hrsa.gov (2024)
  • Prevention Access Campaign. U=U: Undetectable Equals Untransmittable. preventionaccess.org (2024)
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