What is PrEP

What is PrEP

What is PrEP 1028 685 nodMD

Pre-exposure prophylaxis (PrEP) is an HIV prevention approach where HIV-negative individuals can use anti-HIV medications to reduce their risk of acquiring HIV. In fact, studies have shown that PrEP reduces the risk of getting HIV from sex by about 92%- 99% when taken daily. Among people who inject drugs, PrEP reduces the risk of getting HIV by at least 74% when taken daily1. PrEP is not a cure for HIV and it does not protect against other sexually transmitted diseases (STDs) or pregnancy2.

The U.S. Food and Drug Administration (FDA) approved Truvada for PrEP in 2012. This medication combines two medicines (emtricitabine or FTC and tenofovir disoproxil fumarate or TDF) taken as a once-daily oral pill that can be taken with or without food. In Oct. 2019, Descovy (emtricitabine or FTC and tenofovir alafenamide or TAF) was approved for PrEP excluding individuals at-risk from receptive vaginal sex1,2. In the United States, PrEP has been approved by the FDA for use in adolescent patients who weigh at least 35 kg3.

Why use PrEP?

About 1.1 million Americans overall are at substantial risk for HIV and should be offered PrEP4. Among men who have sex with men (MSM) aged 13 to 24 years who are at particularly high risk of acquiring HIV, the rate of new HIV infections increased by 43 percent from 2003 to 20143. According to the Centers for Disease Control and Prevention (CDC), researchers found that while two-thirds of people who could potentially benefit from PrEP are African-American or Latino, they account for the smallest percentage of prescriptions to date. Recently, the CDC reported 18% of people at risk for HIV have been prescribed PrEP4.

Who should not take PrEP?

Individuals, who are HIV infected or recently exposed to HIV, have underlying kidney disease, or those who are not committed to daily medication adherence and close-follow-up should not take PrEP3. Of course, one should talk with a healthcare provider to determine if PrEP is appropriate.

What are the side effects?

Side effects can include upset stomach, nausea, headaches, unintentional weight loss of more than 5%, and a small increase in serum creatinine/worsening kidney function1. However, no serious side effects have been observed and side effects generally subside over time2.

When does PrEP become effective?

It is estimated that it takes at least seven days for PrEP to reach high levels of protection in the body for receptive anal sex. However, it can take up to 21 days for receptive vaginal sex and in those with injection drug use2.

Who should consider taking PrEP?

According to the CDC, PrEP is recommended for people who are HIV-negative who:

  • Have had anal or vaginal sex in the past 6 months and:
  • Have a sexual partner with HIV (especially if the partner has an unknown or detectable viral load)


  • Have not consistently used a condom


  • Have been diagnosed with an STD in the past 6 months
  • PrEP is also recommended for people who inject drugs and:
  • Have an injection partner with HIV


  • Share needles, syringes, or other equipment to inject drugs
  • PrEP should also be considered for people who have been prescribed non-occupational post-exposure prophylaxis (PEP) and:
  • Report continued high-risk behavior


  • Have used multiple courses of PEP

Will PrEP interfere with hormone therapy in transgender individuals?

There are more studies needed on this topic. However, there are currently no known drug conflicts or interactions between the medicines used in PrEP and hormone therapy. One should see their healthcare provider every 3 months for proper follow-up and can ask to have their hormone levels checked2.

Does PrEP have long-term harmful health effects?

People have taken PrEP for up to 5 years and have had no significant health effects. However, the long-term safety of PrEP has still not yet been determined2.

What about pregnancy?

In PrEP trials, women were taken off medication as soon as pregnancy was detected. During these trials, no health problems have been associated with PrEP use by women in early pregnancy or for their offspring. However, the long-term safety of PrEP taken by HIV-uninfected women after fetal (during pregnancy) or infant (during breastfeeding) exposure has not yet been determined. No adverse effects have been found among the infants exposed when the medications were taken as part of a treatment regimen for HIV-infected women during pregnancy or during breastfeeding3.

How long does someone take PrEP?

PrEP must be taken daily. However, individuals may want to stop taking PrEP if their risk of getting HIV becomes minimal due to changes in their lifestyle. However, one should talk with their healthcare provider prior to stopping PrEP.1

How do I get PrEP?

PrEP is available by prescription following a simple visit to your doctor or healthcare provider. Many health insurance plans cover the cost of PrEP. However, a commercial medication assistance program is available for people who need help paying for PrEP5.


  1. https://prepfacts.org/prep/the-basics/
  2. https://www.cdc.gov/hiv/basics/prep.html
  3. https://www.uptodate.com/contents/patient-evaluation-and-selection-for-hiv-pre-exposureprophylaxis?search=PrEP&source=search_result&selectedTitle=2~76&usage_type=default&display_rank=2#H4288900423
  4. https://www.cdc.gov/nchhstp/newsroom/2019/ending-HIV-transmission-test-treat-and-prevent.html
  5. https://www.hiv.gov/hiv-basics/hiv-prevention/using-hiv-medication-to-reduce-risk/pre-exposure-prophylaxis