Preexposure prophylaxis (PrEP) is an HIV prevention treatment that doctors prescribe to people who are HIV-negative but have an increased risk of contracting the virus.

PrEP stands for preexposure prophylaxis. It is a prophylactic treatment for people who do not have HIV but have an increased risk of contracting it. PrEP contains antiretroviral medications, which lower the risk of acquiring HIV for people exposed to the virus.

Antiretroviral medications work by preventing the HIV virus from replicating itself in the body. There are several antiretroviral medications currently approved to prevent HIV.

The Food and Drug Administration (FDA) has approved three types of PrEP.

This article provides more information about PrEP for HIV and discusses its effectiveness and side effects.

The Centers for Disease Control and Prevention (CDC) notes that a healthcare professional may prescribe three different types of PrEP.

Two of these are oral medications, while the other is injectable.


Truvada is one brand of oral PrEP. It is a medication called emtricitabine in combination with tenofovir disoproxil fumarate. It is an option for people who may have a higher risk of contracting HIV through sex or the use of injectable drugs.


Descovy is a second brand of oral PrEP. It is a medication called emtricitabine in combination with tenofovir alafenamide. It is an option for those with an increased chance of contracting HIV through sex. However, the FDA has not approved it for preventing HIV via receptive vaginal sex.


Apretude is a brand of injectable PrEP. The medication is called cabotegravir. It has approval for people at risk of contracting HIV through sex. It must be administered by a healthcare professional every 2 months.

Healthcare professionals recommend PrEP to people who have tested negative for HIV but have an increased chance of contracting the virus.

For instance, PrEP may be beneficial if a person has had vaginal or anal sex in the past 6 months and:

  • has a sexual partner who is living with HIV
  • has received a sexually transmitted infection (STI) diagnosis in the last 6 months
  • has not consistently used a condom, or other barrier method, during sex

Additionally, a person may need PrEP if they use injected recreational drugs and share needles or other equipment with others.

If a person has a partner with HIV and is considering getting pregnant, they should talk with a healthcare professional about taking PrEP.

Adults and adolescents need to weigh at least 77 pounds (lbs.) to take PrEP.

People who think they may have had exposure to HIV cannot take PrEP, but they may be eligible for postexposure prophylaxis, or PEP, which prevents HIV infection.

A person who has had exposure to HIV may be eligible for PEP if they consult a healthcare professional within 72 hours.

For PrEP to be effective, people need to take the medication as prescribed by a healthcare professional.

With proper use, PrEP treatment is 99% effective in reducing the chance of contracting HIV via sex and 74% effective in reducing HIV contraction via injection drug use.

The treatment provides a person with maximal protection from HIV during receptive anal sex after about 7 days.

For people taking PrEP to protect themselves from HIV through receptive vaginal sex or injection drug use, the treatment reaches maximal protection after 21 days.

A person will need to speak with a healthcare professional to access PrEP medications, as they are only available through prescription.

The healthcare professional will prescribe medication and counseling to reduce the likelihood of a person contracting HIV.

People will only be able to begin taking PrEP once a lab test has confirmed that they do not have HIV. During treatment, a person will require routine follow-up appointments with their healthcare professional.

At each of these checkups, they will perform another HIV test. If the tests are still negative, the person can continue receiving their medications.

It is possible to begin taking PrEP or continue taking it without visiting a healthcare professional in person. People can have a phone or video consultation and use mail-in self-testing.

A person can also use this online tool to locate a PrEP provider.

Most insurance plans cover PrEP treatment. The coverage should include the medication, lab tests, and clinic visits.

Learn more about Medicare and Truvada.

With no insurance

A person without insurance may be eligible for Medicaid or Affordable Care Act plans.

Some state Medicaid programs in the United States cover PrEP. People looking for more information on programs that cover PrEP can speak with a doctor or pharmacist.

If a person is not eligible for Medicaid, certain programs in the United States provide PrEP at a reduced cost or for free.

One such program — Ready, Set, PrEP — should cover the cost of the medication for people who meet the eligibility criteria. In addition, a person can get lab tests and clinic visits at a community health center that uses a sliding scale fee.

Other programs that may offer PrEP at a reduced fee include co-pay assistance programs and state PrEP assistance programs.

Experts consider PrEP to be safe, but any medication can cause side effects.

Side effects that people may experience include:

These side effects are usually mild and resolve without intervention. However, people should seek medical attention if they experience bothersome side effects that are severe or do not improve.

The following list shows some additional side effects of Truvada:

People may need to stop taking PrEP for several reasons, including:

  • changes in a person’s life that reduce their chance of contracting HIV
  • lack of adherence to taking one pill a day
  • side effects interfering with activities of daily living
  • blood test results indicating that the body is responding negatively to PrEP

In these cases, a person can discuss alternative options with their healthcare professional.

Restarting it

Anyone who wants to start taking PrEP again after stopping its use must take another HIV test to ensure they do not have the virus before starting the treatment.

While the medications doctors use for PrEP are the same as those they prescribe for treating HIV, taking only Truvada or Descovy to treat HIV is ineffective.

Inadequate treatment for HIV can increase the risk of viral resistance to effective medications.

Can a person take it just once?

PrEP is primarily for people who have an ongoing risk of contracting HIV.

PrEP takes time to reach its maximal protection, so taking the medication just once will not provide full protection against HIV infection.

If a person believes that they have already had exposure to HIV, PrEP will not provide adequate protection. PEP medication is an option for preventing HIV in people exposed to HIV in the past 72 hours.

While PrEP is suitable for people who have a continual chance of contracting HIV, PEP prevents HIV in people who have had exposure to the virus.

Once a person becomes exposed to HIV, they must start PEP as soon as possible, as it will only be effective within 72 hours of exposure.

A person will need to take PEP for 28 days.

There are different PEP regimens for children, people with kidney failure, and pregnant people.

PEP is only for emergency situations. If a person has frequent exposure to HIV, they should talk with a healthcare professional about taking PrEP.

People can decide to take PrEP treatments only when in at-risk situations, even if it is not ongoing.

Some evidence exists to suggest that the 2-1-1 schedule provides protection for gay and bisexual males when engaging in anal sex without a condom.

The 2-1-1 schedule recommends taking two pills of Truvada or Descovy 2–24 hours before having sex. The person then takes one pill 24 hours after the first dose and one pill 24 hours after the second dose.

Currently, this type of treatment is not part of the CDC’s guidelines for PrEP.

PrEP is a treatment regimen for people who have a high risk of contracting HIV.

Adults and adolescents who weigh at least 77 lb may use this treatment if they have a continual risk of exposure to HIV through sex without a barrier method or injection drug use.

PrEP is an effective treatment when a person takes the medication as prescribed by the healthcare professional. People may experience some mild side effects of the medication, including diarrhea, fatigue, and headaches.

Most insurance plans will cover the cost of PrEP. However, if a person does not have insurance, some programs may cover PrEP for free or at a reduced price.