PrEP FAQs

PrEP is short for pre-exposure prophylaxis. It is an FDA-approved prescription medication that protects against getting HIV. Similar to birth control, but for HIV.

It is available as both a pill and long-acting injectable (or shot). Both forms of PrEP are highly effective at preventing HIV when taken as prescribed. As a pill, PrEP is taken once a day. Another option is to get it as an injection every two months from a healthcare provider. A healthcare provider can discuss the benefits of both options. It takes some time, usually a few weeks after starting PrEP, for it to reach maximum protection. You must continue using PrEP to maintain a high-level of protection.

As part of ongoing PrEP, you will need to see a healthcare provider every few months to be re-tested for HIV and other health checks.

PrEP may also be taken “on demand,” referred to as PrEP 211, in advance of sex. For more about using PrEP in this form, see: CDC guidance for On-Demand PrEP.

Most people pay little or nothing for PrEP. Federal law requires that almost all health insurers cover daily oral PrEP. Insurers cannot charge people on daily PrEP any out-of-pocket fees such as copays for the medication or the required clinic visits. If you do not have health insurance, or need help paying for PrEP, financial assistance is often available. A PrEP navigator can help you with options.

There is currently no requirement for insurers to cover injectable PrEP, and unfortunately, many insurers do not cover it. There are financial assistance programs that may help to get injectable PrEP.

CDC, Preventing HIV with PrEP. January 2024.
FDA, FDA Approves Second Drug to Prevent HIV Infection as Part of Ongoing Efforts to End the HIV Epidemic. October 2019.
FDA, FDA Approves First Injectable Treatment for HIV Pre-Exposure Prevention. December 2021.

PrEP is very effective when taken as prescribed.

According to the U.S Centers for Disease Control and Prevention (CDC), taking PrEP daily reduces the risk of getting HIV from sex by more than 99 percent. For people who inject drugs, PrEP also reduces the risk of getting HIV by 74 percent when taken consistently.

When you start taking the daily PrEP pill, it takes about 7 days to reach the maximum level of protection against HIV for anal sex and 21 days for vaginal sex or injection drug use. PrEP works less well when people don’t take it daily as prescribed.

Taking PrEP as a shot is also highly effective at preventing HIV though it is currently not recommended for people who inject drugs.

Both forms of PrEP do not protect against other sexually transmitted diseases (STDs). Condoms reduce the risk of gonorrhea, chlamydia, syphilis and other common STDs, as well as pregnancy.

CDC: Pre-Exposure Prophylaxis (PrEP). July 2022
CDC, Preventing HIV with  PrEP. January 2024.

PrEP as a daily pill:

Daily PrEP must be taken for some time before a potential exposure to HIV to be effective. According to the U.S. Centers for Disease Control and Prevention (CDC), PrEP reaches maximum protection against contracting HIV through receptive anal sex after about 7 days of daily use. For receptive vaginal sex and injection drug use, the CDC estimates that PrEP reaches maximum protection after about 20 days of daily use. Missing daily doses can lower PrEP’s effectiveness.

PrEP as an injectable:

According to the CDC, it is not yet known how long it takes for PrEP shots to reach maximum effectiveness during sex.

CDC, Preventing HIV with PrEP. January 2024.

Federal law requires that almost all insurers cover PrEP in pill form. Insurers also cannot charge anything, such as copays or deductible payments, for the prescriptions. This means that both the medication and the routine clinic visits needed to maintain a prescription to PrEP in pill form must be totally free.

If you do not have insurance, there are financial assistance programs that may be able to help with the cost of the medication and the clinic visits.

Currently, injectable PrEP is not widely covered by insurers. However, there are financial assistance programs that may be able to help.

See: I don’t have insurance, can I still get PrEP?
See: If I have insurance, are there ways to make PrEP more affordable?

PrEP is approved for all adults and adolescents (weighing at least 77 pounds) who are at risk of contracting HIV. Some types of PrEP are only approved for anal sex. Talk with your healthcare provider about which type of PrEP is right for you.

The U.S. Centers for Disease Control and Prevention (CDC) recommends PrEP for those who have had anal or vaginal sex in the past six months and who have had:

• A partner living with HIV, especially if that person has an unknown or detectable viral load. (This means either they are not on treatment for HIV or their treatment has not successfully suppressed their virus. People with HIV whose virus is undetectable, thanks to prescribed HIV treatment, cannot transmit it.)
• Any sex partners whose HIV status is unknown, especially if any of the sex was condomless.
• Has had a bacterial sexually transmitted disease (STD) in the past six months, including gonorrhea, chlamydia or syphilis. (However, for those who have receptive vaginal sex, chlamydia infection is not considered an indication that PrEP may be warranted.)

The CDC also recommends that people who may be at risk of contracting HIV in the future discuss this with a healthcare provider to see if PrEP is right for them.

If you’ve taken PEP:

People who have taken post-exposure prophylaxis (PEP), which is a month of medications started within 72 hours after a potential exposure to HIV, may also be good PrEP candidates. The CDC recommends that people who have taken PEP more than once consider PrEP.

People who inject drugs:

For people who inject drugs, the CDC recommends PrEP for those with an injection partner who has HIV or who have shared injection drug equipment with others within the past six months.

Planning a pregnancy:

If you and your partner are considering getting pregnant and one of you has HIV, PrEP can help you conceive a child without transmitting HIV. If the HIV-positive partner is on antiretroviral (ARV) treatment and has an undetectable viral load, they cannot transmit the virus through sex. If the HIV-negative partner takes PrEP, this can add another layer of protection.

Speaking with the healthcare provider:

Not all healthcare providers are knowledgeable about PrEP. Some may not know how to speak without judgment about sex or injection drug use. That said, there are many healthcare providers who specialize in serving populations who use PrEP. Click here to find a PrEP provider near you.

CDC, Preventing HIV with  PrEP, January 2024.
CDC, Pre-Exposure Prophylaxis 2021 Update [PDF].

PrEP requires a prescription in most places. Any medical professional who can prescribe medications, including doctors and nurse practitioners, can prescribe PrEP.

If you don’t have a regular healthcare provider or they are reluctant to prescribe PrEP, there are organizations that can help you get on PrEP. This may include finding a provider and identifying sources of financial assistance if necessary. Click here to find a PrEP provider near you.

While highly effective at protecting against HIV, PrEP does not protect against other sexually transmitted diseases (STDs). Condoms are a highly effective means of preventing transmission of HIV and many other STDs when used consistently and correctly. Condoms are the only method of protection that also prevents pregnancy and STDs.

See: Let’s Talk About Condoms

If you are uninsured or underinsured, there may be resources available that can help pay for PrEP and the necessary clinic visits and tests.

Depending on your income, you may be eligible to get PrEP at no cost as part of a program offered by its manufacturers. Gilead Sciences’ Advancing Access Program may also be available to those on Medicare who don’t have Part D prescription drug coverage. To determine if you are eligible, your medical provider needs to submit an application for you. For more information call (800) 226-2056. Assistance programs may also be available through ViiVConnect or by calling (844)-588-3288.

There are programs that can help you get on PrEP, even if you don’t have insurance. Click here for resources in HIV.gov’s How can I pay for PrEP? Fact Sheet.

To find affordable health insurance coverage options in your state, go to: healthcoverage.greaterthan.org.

Federal law requires that almost all insurers cover PrEP in pill form. Insurers also cannot charge anything, such as copays or deductible payments, for the prescriptions. This means that both the medication and the routine clinic visits needed to maintain a prescription to PrEP in pill form must be totally free.

If for any reason insurers still charge for PrEP in pill form, Gilead Sciences’ Advancing Access Co-Pay Coupon provides up to $7,200 per year to cover out-of-pocket expenses for PrEP. This includes copays, coinsurance and deductibles. There is no monthly limit. The program does not restrict benefits based on income. However, it is not available for those on Medicaid, Medicare Part D or any other government prescription drug programs. For more information call (800) 226-2056.

Another option for people who get their PrEP covered by their insurance, including Medicare, is the Patient Advocate Foundation, which provides up to $7,500 per year to help pay for costs related to the prescription. Approval is based on your yearly income. If you earn less than 400 percent of the federal poverty level (or about $54,360 for an individual with no dependents), you may qualify for this program. For more information, click here or call (866) 512-3861 and select option 1.

Yes. Both Medicaid, as well as Medicare, should cover PrEP in pill form.

Depending on what state you live in, Medicaid may require your physician to obtain a pre-approval for PrEP before you fill your prescription.

If you are on Medicare but do not have Part D prescription drug coverage, you may be able to receive PrEP for free from its manufacturer if you have a low income. You may also be eligible for co-pay assistance if you are on Medicare.

See: I don’t have insurance, can I still get PrEP?
See: If I have insurance, are there ways to make PrEP more affordable?

At your first visit, you will likely be asked some questions to help you determine if PrEP is a good fit. This may include questions about your sexual history and your use of condoms. Talk with your healthcare provider about your preferred method of PrEP and if they offer it.

You will be tested for HIV as well as hepatitis B. You will also have your kidney function checked. You may also be screened for other sexually transmitted diseases (STDs). Depending on which type of oral PrEP you are going to take, you may also have your triglycerides and cholesterol tested.

Oral PrEP

After you get your PrEP prescription, you will need to have a check-up every three months. At these visits, you will be re-tested for HIV and should receive periodic screening for other STDs and your kidney function. Depending on which PrEP pill you take, you may need to do an annual monitoring of triglycerides, cholesterol and weight.

Injectable PrEP

The PrEP shot is an intramuscular injection in the buttocks. Typically, it initially requires two shots administered one month apart, and then one shot every two months thereafter. At your clinic visits, you will be tested for HIV and STDs.

You can go on and off PrEP at different times in your life, depending on whether you are at risk of HIV. But you should do so under the guidance of a healthcare provider.

See: How do I get PrEP?

CDC, Pre-Exposure Prophylaxis 2021 Update [PDF].

You can go on and off PrEP at different times in your life, depending on whether you are at risk of HIV. But you should do so under the guidance of a health care provider.

Before restarting PrEP, you will need to get tested for HIV again and renew your prescription.

If you are taking daily PrEP, it takes about 7 days after re-starting to take the pill for it to reach maximum effectiveness. For cisgender women, oral PrEP takes about 20 days to reach this point.

See: How quickly does PrEP start working?

No. PrEP must be taken for some time before a possible exposure to HIV to be effective. PrEP is short for pre-exposure prophylaxis.

If you think you may have been exposed to HIV, PEP, or post-exposure prophylaxis, is highly effective at preventing the virus from taking hold in the body. This involves starting three antiretroviral medications within 48 to 72 hours of the potential exposure to HIV. The medications should be taken daily for one month. When accessing PEP, time is of the essence. So if you have a healthcare provider, you need to see them immediately. Otherwise, go to an urgent care center or emergency room for a prescription.

See: How quickly does PrEP start working?; What is PEP?

CDC, Post-Exposure Prophylaxis (PEP). August 2022.

PEP, short for post-exposure prophylaxis, is a highly effective way of using medications shortly after a potential exposure to HIV to prevent HIV from taking hold in the body. PEP must be started within 72 hours–but ideally 48 hours–of a potential exposure to the virus. It involves taking medications daily for one month.

Time is of the essence when accessing PEP. If you have a healthcare provider, ask for an immediate appointment. Otherwise, go to an urgent care clinic or emergency room for a prescription.

For ongoing protection, consider PrEP, a prescription medication that is highly effective at protecting against HIV. Unlike PEP, it is taken before a potential exposure to the virus.

See: What is PrEP?

CDC, Post-Exposure Prophylaxis (PEP). August 2022.

No. While PrEP is highly effective at preventing HIV, it does not protect against other sexually transmitted diseases (STDs). When used consistently and correctly, condoms protect against HIV, as well other common STDs, in particular gonorrhea, chlamydia.

CDC, Preventing HIV with PrEP. January 2024.

Many people on PrEP report no or minimal side effects.

For daily oral PrEP, the typical side effects may include diarrhea, nausea, headache, fatigue and stomach pain. But they tend to go away within a few weeks.

For injectable PrEP, side effects can include reactions at the site of injection, diarrhea, headache, fever, fatigue, sleep problems, nausea, dizziness, passing gas, stomach pain, vomiting, muscle pain, rash, loss of appetite, drowsiness, back pain and upper respiratory infection.

If you are taking PrEP and experiencing side effects that are severe or do not go away, tell the healthcare provider who prescribed PrEP.

CDC, Preventing HIV with PrEP. January 2024.
FDA, Apretude drug label [PDF]. December 2021.

Yes. If you’ve recently had a sexually transmitted disease (STD), this is a sign that you might be at risk of HIV. Being at risk of HIV likely makes you a good candidate for PrEP. There is no evidence that having an STD lowers how well PrEP works.

If you have been diagnosed with an STD, you should receive treatment for it. Many STDs are curable, and all are treatable. There are vaccines available for HPV (which causes genital warts and raises the risk of certain cancers) and hepatitis B.

PrEP only protects against HIV. When used consistently and correctly, condoms protect against pregnancy and HIV, as well as other common STDs, in particular gonorrhea and chlamydia.

If you are taking PrEP as a daily pill and you miss a dose, try to get back on a daily schedule as soon as possible. For men who have sex with men, missing one to three doses per week likely does not reduce PrEP’s effectiveness. Taking fewer than four doses per week is expected to lower PrEP’s effectiveness for this group.

People who have vaginal sex need to take PrEP more consistently to get maximum protection. Missing even one dose per week may lower PrEP’s effectiveness.

If you are having difficulty keeping up with PrEP’s daily schedule, you should talk with the healthcare provider. You might discuss with them switching to injectable PrEP instead.

If you are receiving PrEP as a shot, it is important to get your shot every 2 months to keep up maximum protection.

CDC, Pre-Exposure Prophylaxis 2021 Update [PDF].

Alcohol and drug use should not directly affect how well PrEP works. However, substance use may affect how consistently you take the medication if you are taking PrEP as a daily pill. Missing doses can lower PrEP’s effectiveness.

See: What if I miss a dose of PrEP?

The U.S. Food and Drug Administration (FDA) does not list any antidepressants as potential conflicts on its official safety information on any of the medications approved for use as PrEP.

You should let your doctor know all medications, supplements and vitamins you are taking to avoid potential drug interactions.

FDA, Highlights of Prescribing Information: Descovy [PDF]. October 2019.
FDA, Highlights of Prescribing Information: Truvada [PDF]. July 2012.
FDA, Apretude drug label [PDF]. December 2021.

If you or your partner are living with HIV and are considering getting pregnant, talk with your healthcare provider. PrEP may be an option to help protect you and your baby from getting HIV while you try to get pregnant and during pregnancy.

CDC, #ShesWell: PrEP for Women. May 2024.

PrEP as a daily pill is not known to affect the level of gender-affirming hormones in the body. However, it is possible that such hormones might slightly lower one of the two medications included in the tablets. This slight reduction probably does not lower PrEP’s effectiveness provided the pill is taken daily.

Injectable PrEP is not known to have any interactions with gender affirming hormones.

AIDS Map, Interactions between PrEP and gender-affirming hormone therapy. March 2021
FDA, Apretude drug label [PDF]. December 2021.

If someone who has HIV takes PrEP, the virus can develop resistance to some medications used to treat the virus. This may limit HIV treatment options.