Pre-exposure prophylaxis (PrEP) for HIV is effective at decreasing the incidence of HIV infection among men who have sex with men (MSM).1-4 However, since the first PrEP formulation was approved in 2012, rates of other sexually transmitted infections (STIs) have increased in this population as well as in the general population.5,6 More than 2.5 million cases of chlamydia, gonorrhea, and syphilis were reported in the United States between 2020 and 2021.7

When left untreated, STIs can lead to long-term, irreversible health issues, such as chronic pelvic pain, infertility, and in some cases, cancer. Evidence in the literature is compelling and the need for prevention of other STIs is crucial to keeping this population healthy and reducing health care costs.4 Adolescents and young adults, MSM, and pregnant women are disproportionately impacted by STIs as are Black, Hispanic/Latino, and other minority communities.8

Key Points  
• PrEP decreased HIV rates in the MSM population but also led to higher rates of other STIs  
• Rates of HIV infection and other STIs are disproportionately high in minority populations  
• Patient education and more frequent STI testing can help to reduce HIV and other STIs  
• It is recommended that at-risk patients be tested for STIs every 3 months  

PrEP Use and HIV Infection Rates

Decreasing the incidence of HIV infection in MSM has been a goal since the emergence of the disease in the 1980s. Many strategies have been used including rapid testing for HIV, better access to testing and care, driving HIV viral loads down to undetectable levels so transmission is unlikely to occur, and most recently (since 2012) the availability of HIV PrEP.

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In 2019, the United States Preventive Services Task Force recommended offering HIV PrEP proactively to groups who are at high risk of acquiring HIV infection because of the convincing evidence of the benefit of prevention with the small risk of adverse side effects.9 Since then, the of new HIV infections decreased markedly following the availability of PrEP and increased testing in the US. An 8% decrease in new HIV infections was found from 2015 to 2019 (37,800 to 34,800), after a period of general stability.10

However, racial/ethnic disparities exist in the uptake of PrEP and new HIV infection rates. Of PrEP-eligible people in 2020, PrEP use was reported in only 9% of Black individuals and 16% of Hispanic individuals compared with 66% of White individuals.10 Black individuals have an 8-fold higher risk and Hispanic/Latino have a 4-fold higher risk for new HIV infections compared with White people.10 These disproportionate HIV infection rates by ethnicity and race are important to consider when discussing the increases in STIs in these populations.

Increased STI Infections With HIV Prophylaxis

Coinciding with the decrease in HIV infection rates has been an increase in other STIs. In 2021, 1,644,416 chlamydia cases, 710,151 gonorrhea cases, and 176,713 syphilis cases were reported to the Centers for Disease Control and Prevention (CDC); however, the CDC notes uncertainty and difficulty interpreting data from 2020 and 2021 because of the impact of the COVID-19 pandemic on reporting rates.7

Prepandemic rates from 2012 to 2019 show that STIs rates increased disproportionately when stratified by ethnicity and race (Figures 1-3)4:

  • infection rates increased by 20% from 2012 to 2019. This includes a 2% increase in the Black population, no increase in the Hispanic/Latino population, and an 18% increase in the White population.
  • infection rates increased by 75% between 2012 and 2019. These rates increased by 42% in the Black population, 91% in the Hispanic/Latino population, and 133% in the White population.
Figure 1. Chlamydia infection rates by ethnicity/race. Source: CDC.4
Figure 2. Gonorrhea infection rates by ethnicity/race. Source: CDC.4
Figure 3. Primary/secondary syphilis infection rates. Source: CDC.4

Although the greatest increase in rates of STIs (chlamydia, gonorrhea, and syphilis) are found in White individuals, the overall infection rates of syphilis and gonorrhea are considerably higher in Black and Hispanic/Latino populations than in White populations.4 Thus, targeted interventions should be directed toward these communities to help to lower the infection rates.

Nguyen et al performed a retrospective cohort study to compare the incidence of STIs 12 months before and 12 months after the initiation of PrEP and investigate how STI rates compare among individuals receiving PrEP vs those receiving post-exposure prophylaxis (PEP).11 The study demonstrated that all (non-HIV) STI incidence rates increased after PrEP initiation, and the PrEP group was at higher risk for STIs compared with the PEP group.

In a meta-analysis of data from 20 trials and observational studies of PrEP in MSM that reported data on STI incidence during the study period, findings from the majority of studies showed that sexual behavior and/or STI incidence remained stable or decreased. However, the subgroup of MSM taking PrEP who engaged in high-risk behaviors (eg, condomless sex with casual partners) had high rates of syphilis, gonorrhea, chlamydia, and hepatitis C.12 In this subgroup, more frequent STI testing and treatment options may be needed to help reduce the incidence of STIs.

Clinical Intervention to Reduce STI Rates

Clinical interventions must be considered to stem the rising rates of STIs among MSM who engaged in high-risk behaviors. Interventional strategies may be separated into 2 areas: 1) behavioral modification via patient education and 2) other clinical strategies such as more frequent STI testing, antibacterial prophylaxis, and better clinician education for a proactive patient approach.13

Behavioral Counseling and Patient Education

Behavioral counseling regarding safer sex practices to reduce the incidence of STIs in the population at large and specifically in the MSM population was studied in 6 systematic reviews covering 91 articles on the topic. Some of the studies demonstrated lower STI rates after behavioral counseling, noting that this intervention strategy may be helpful, but it was not likely to benefit MSM as their rates did not decrease with behavioral counseling.14 Attempts at behavioral counseling alone are not likely to significantly impact STI rates in the MSM population. The combination of patient education and more frequent STI testing is a more comprehensive approach to reducing STI infection rates in this population. Targeted outreach for Black and Hispanic/Latino individuals is essential given the disproportionately high STI infection rates in these populations.

Patient counseling also provides an opportunity to have a conversation about PrEP for patients who are HIV-negative but at risk for HIV infection. This may encourage more frequent HIV testing in this group of patients. And because PrEP is monitored at regular intervals by a provider these visits provide an opportunity for both behavioral counseling (to include prevention strategies and use of condoms) and STI screening at frequent intervals.15,16

Current CDC guidelines (2021) recommend that all patients taking PrEP should be seen every 3 months to17:

Providers using these new guidelines will be able to identify STI infections more proactively and help to decrease the spread of infection in patients who do not know they are infected.

Bacterial Prophylaxis

In a review of research on use of bacterial prophylaxis for STIs in the MSM population after condomless sexual activity, doxycycline prophylaxis showed high efficacy against chlamydia and syphilis in 2 small short-term randomized controlled trials but limited efficacy against gonorrhea.18 A predictive modeling study examining the impact of doxycycline PrEP on syphilis rates in Australian MSM showed that if 50% of MSM used this intervention and it was 70% effective, in 12 months the syphilis infection rate would decrease by 50%, and after 10 years by 85%.19

In an open-label, study involving 501 MSM and transgender women taking PrEP or living with HIV infection who had a non-HIV STI in the past year, participants were randomized to receive 200 mg of doxycycline within 72 hours after condomless sex or standard care without doxycycline.20 Doxycycline prophylaxis was linked to a lower risk of gonorrhea, chlamydia, or syphilis in the PrEP cohort (relative risks, 0.45 for gonorrhea, 0.12 for chlamydia, and 0.13 for syphilis). In the cohort of patients with HIV, the relative risks among those using doxycycline were 0.43, 0.26, and 0.23, respectively.

More research is needed and a significant number of studies are ongoing to determine if this is a reasonable future approach.


Better patient education, targeted intervention in the Black and Hispanic/Latino populations, more frequent STI screening and treatment, and behavioral modification strategies can help to reduce the incidence of HIV infection as well as the increased incidence of other STIs. These interventions will improve overall population health and help to contain health care costs.

Carl Garrubba, DMSc, PA-C, is Dean of the School of Health and Natural Science at Dominican University of California in San Rafael, California; Laura Witte, PhD, PA-C, is an associate professor at the University of Lynchburg in Lynchburg, Virginia.


1. Grant RM, Lama JR, Anderson PL, et al; iPrEx Study Team. Preexposure chemoprophylaxis for HIV prevention in men who have sex with men. N Engl J Med. 2010;363(27):2587-2599. doi:10.1056/NEJMoa1011205

2. McCormack S, Dunn DT, Desai M, et al. Pre-exposure prophylaxis to prevent the acquisition of HIV-1 infection (PROUD): effectiveness results from the pilot phase of a pragmatic open-label randomised trial. Lancet. 2016;387(10013):53-60. doi:10.1016/S0140-6736(15)00056-2

3. Molina JM, Capitant C, Spire B, et al; ANRS IPERGAY Study Group. On-demand preexposure prophylaxis in men at high risk for HIV-1 infection. N Engl J Med. 2015;373(23):2237-2246. doi:10.1056/NEJMoa1506273

4. Centers for Disease Control and Prevention. NCHHSTP AtlasPlus. Updated February 21, 2023. Accessed June 8, 2023.

5. Chow EPF, Grulich AE, Fairley CK. Epidemiology and prevention of sexually transmitted infections in men who have sex with men at risk of HIV. Lancet HIV. 2019;6(6):e396-e405. doi: 10.1016/S2352-3018(19)30043-8

6. Scott HM, Klausner JD. Sexually transmitted infections and pre-exposure prophylaxis: challenges and opportunities among men who have sex with men in the US. AIDS Res Ther. 2016;13:5. doi:10.1186/s12981-016-0089-8

7. Centers for Disease Control and Prevention. Infections continue to forge ahead, compromising the nation’s health. Updated April 11, 2023. Accessed June 8, 2023.

8. US Department of Health and Human Services. 2020. Sexually Transmitted Infections National Strategic Plan for the United States: 2021–2025. Washington, DC. Accessed June 8, 2023.

9. US Preventive Services Task Force; Owens DK, Davidson KW, Krist AH, et al. Preexposure prophylaxis for the prevention of HIV Infection: US Preventive Services Task Force recommendation statement. JAMA. 2019;321(22):2203-2213. doi:10.1001/jama.2019.6390

10. Centers for Disease Control and Prevention. PrEP for HIV prevention in the US. Updated November 23, 2021. Accessed June 8, 2023.

11. Nguyen VK, Greenwald ZR, Trottier H, et al. Incidence of sexually transmitted infections before and after preexposure prophylaxis for HIV. AIDS. 2018;32(4):523-530. doi:10.1097/QAD.0000000000001718

12. Werner RN, Gaskins M, Nast A, Dressler C. Incidence of sexually transmitted infections in men who have sex with men and who are at substantial risk of HIV infection — a meta-analysis of data from trials and observational studies of HIV pre-exposure prophylaxis. PLoS One. 2018;13(12):e0208107. doi:10.1371/journal.pone.0208107

13. Traeger MW, Cornelisse VJ, Asselin J, et al; PrEPX Study Team. Association of HIV preexposure prophylaxis with incidence of sexually transmitted infections among individuals at high risk of HIV infection. JAMA. 2019;321(14):1380-1390. doi:10.1001/jama.2019.2947

14. Brookmeyer KA, Hogben M, Kinsey J. The role of behavioral counseling in sexually transmitted disease prevention program settings. Sex Transm Dis. 2016;43(2 Suppl 1):S102-112. doi:10.1097/OLQ.0000000000000327

15. Hart TA, Noor SW, Berlin GW, et al; Engage Study. Pre-exposure prophylaxis and bacterial sexually transmitted infections (STIs) among gay and bisexual men. Sex Transm Infect. 2023;99(3):167-172. doi:10.1136/sextrans-2021-055381

16. Kumar S, Haderxhanaj LT, Spicknall IH. Reviewing PrEP’s effect on STI incidence among men who have sex with men-balancing increased STI screening and potential behavioral sexual risk compensation. AIDS Behav. 2021;25(6):1810-1818. doi:10.1007/s10461-020-03110-x

17. US Public Health Service. Preexposure prophylaxis for the prevention of HIV infection in the United States — 2021 Update. Accessed June 8, 2023.

18. Grant JS, Stafylis C, Celum C, et al. Doxycycline prophylaxis for bacterial sexually transmitted infections. Clin Infect Dis. 2020;70(6):1247-1253. doi:10.1093/cid/ciz866

19. Wilson DP, Prestage GP, Gray RT, et al. Chemoprophylaxis is likely to be acceptable and could mitigate syphilis epidemics among populations of gay men. Sex Transm Dis. 2011;38(7):573-579. doi:10.1097/OLQ.0b013e31820e64fd

20. Luetkemeyer AF, Donnell D, Dombrowski JC, et al; DoxyPEP Study Team. Postexposure doxycycline to prevent bacterial sexually transmitted infections. N Engl J Med. 2023;388(14):1296-1306. doi:10.1056/NEJMoa2211934