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How Effective is HIV PrEP and Who Should Take It?

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PrEP stands for pre-exposure prophylaxis. It is medication taken to help prevent getting HIV from sex or injection drug use. PrEP can be an integral part of sexual health and overall health.

Currently, there are two oral medications and one injectable medication approved for PrEP. The oral medications are Truvada (approved July 2012) and Descovy (approved October 2019). The injectable medication is Apretude (approved at the end of 2021 and now available).

The right option for an individual depends on multiple factors including gender assigned at birth, other medical conditions, other medications a person may be taking, personal preferences, cost and insurance coverage, and availability to follow up with your provider in person or virtually.

PrEP will NOT protect against other sexually transmitted infections (STIs) including HPV (human papilloma virus), chlamydia, gonorrhea, viral hepatitis, syphilis and herpes. For this reason, condoms are still recommended. Also, routine screenings for other STIs and discussing appropriate vaccinations with your health care provider are also recommended. Vaccinations may include protection from viral hepatitis, HPV, meningitis, and pneumococcal infections, depending on the individual’s history and risk factors.

Who should use PrEP?

PrEP is for any person who does not have HIV but is at increased risk of acquiring an HIV infection. This includes adults and adolescents over 35 kilograms (approximately 77 pounds). Laws vary state by state on an adolescent’s ability to access PrEP without parental consent.

Who should not use PrEP?

  • If you don’t know your HIV status and don’t want to get tested
  • You are HIV positive
  • Don’t have time or interest in routine testing and medical visits every three to six months
  • Individuals with recent HIV exposure, in whom post-exposure prophylaxis (PEP) may be more appropriate

How is PrEP taken?

Oral PrEP is meant to be taken daily. This reduces the the chance of contracting HIV from sex by up to 99%. There is less information on effectiveness in reducing HIV from IV drug use, but it is thought to reduce the risk of contracting HIV by at least 74%.

Injectable PrEP is administered into the muscle. There is an optional one-month oral lead in period to assess tolerability. After the first injection, a second is done one month later and then every two months. The injection must be done by a medical provider.

Taking PrEP only when at increased risk is known as “On-Demand PrEP” or “Event-Driven PrEP.” Guidance on this method is provided by a limited number of health departments, and some international health organizations. This method is at present not recommended by the CDC. However, for those who are considering On-Demand PrEP, limited evidence is only available for cisgender gay, bisexual and other men who have sex with men. On-Demand PreP can only be done with Truvada. The most widely used way is the 2-1-1 regimen. In this regimen, two tablets of Truvada are taken between two and 24 hours prior to sex, one tablet 24 hours later, and one tablet 24 hours after the second dose. If sexual activity continues, one tablet is taken every 24 hours until 48 hours after last day of sexual activity. Different studies have shown effectiveness at 86% or higher.

When are you considered protected?

This various by sexual activity:

  • For receptive anal sex (bottoming), oral PrEP reaches maximum effectiveness after seven days of daily use
  • For receptive vaginal sex and injection drug use, oral PrEP reaches maximum effectiveness after 21 days of daily use.
  • No data is available for insertive anal sex (topping) or insertive vaginal sex, and most providers recommend at least 21 days.

No information available at present when injectable is considered effective.

Are there side effects on PrEP?

All medications carry a risk of a potential side effects. Generally, PrEP is well tolerated. Some people may experience self-limited episodes of headaches, abdominal pain, nausea, diarrhea, and muscle aches. These usually resolve within a few weeks.

There is the potential for more serious side effects including but not limited to kidney or liver injury, and in some individuals, medication may need to be discontinued and other options discussed with the healthcare provider.

In order to make sure you are still protected, and not having negative side effects, and also making sure you are not experiencing any other STI routine period labs are necessary. If tests do show other STIs treatment recommendations will be made. In the rare case of a positive HIV test while on PrEP, linkage to an HIV care experience provider will be made, and counseling on HIV offered.

How much does PrEP cost?

Cost various by medication selected and insurance plan. A generic formulation of Truvada has been available since late 2020 and this has expanded access and reduced cost for many individuals. In addition the medications often have copay cards which assist with cost. There are also options for individuals who do not have prescription medication coverage.

At Ochsner, our Specialty Pharmacy department, experienced in PrEP can help research resource options.

For more information

A PrEP experienced health care provider can help address any other concerns you may have. In addition, the CDC offers more information and resources.

Learn more about HIV PrEP


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