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- Presentation
STI Pre- and Post-Exposure Prophylaxis: HIV and Bacterial STI Prevention in Dermatology
Description
The speaker, a dermatologist, explains why clinicians should know about HIV and bacterial STI pre- and post-exposure prophylaxis, especially when caring for patients with STI-related skin findings such as secondary syphilis, genital warts, or herpes. He defines post-exposure prophylaxis as taking medication after exposure to prevent disease and pre-exposure prophylaxis as taking medication in anticipation of exposure. For HIV, he reviews oral PrEP options such as Truvada and Descovy, injectable cabotegravir, and the newer long-acting capsid inhibitor lenacapavir, which may eventually allow twice-yearly or even yearly dosing. He discusses efficacy, adherence advantages, and side effects, including kidney and bone effects with tenofovir-based drugs and injection-site nodules with lenacapavir. He also emphasizes that dermatologists may encounter patients seeking PrEP directly or those who should be considered after a recent STI. For bacterial STI prevention, he covers doxycycline post-exposure prophylaxis, now recommended by the CDC for certain high-risk groups, and notes emerging evidence for pre-exposure use as well. He also highlights a retrospective study suggesting that patients taking doxycycline for acne may have reduced bacterial STI rates, while stressing antibiotic stewardship and ongoing questions about resistance and generalizability.
View moreConclusions
- Dermatologists should recognize STI pre- and post-exposure prophylaxis as part of routine care, especially when patients present with STIs or other sexually transmitted dermatologic findings.
- HIV PrEP is highly effective, with oral, injectable, and long-acting options that can substantially reduce transmission when used consistently.
- Newer PrEP agents such as cabotegravir and lenacapavir may improve adherence and prevention outcomes because they require far less frequent dosing than daily oral therapy.
- Tenofovir-based PrEP can cause small, generally non-progressive changes in kidney function and bone density, while tenofovir alafenamide appears to have a better renal and bone safety profile than tenofovir disoproxil fumarate.
- Lenacapavir may represent a major future advance in HIV prevention, but current data also show injection-site nodules and the need to watch for rare breakthrough infections and resistance.
- Doxycycline post-exposure prophylaxis reduces bacterial STI risk in high-risk populations, particularly for chlamydia and to a lesser extent syphilis and gonorrhea.
- The current evidence for doxycycline STI prevention is strongest in men who have sex with men and transgender populations, with much less certainty in other groups.
- Routine doxycycline use for acne may incidentally lower bacterial STI risk, suggesting a possible broader preventive effect that warrants further study.
- Available data do not show major doxycycline-driven resistance among the targeted bacterial STIs, though resistance effects in non-target organisms remain an area of concern.
- Dermatologists can meaningfully improve sexual health outcomes by counseling patients, initiating PrEP or doxy-PEP when appropriate, and coordinating STI screening and monitoring.
- Grant RM, Lama JR, Anderson PL, et al. Preexposure chemoprophylaxis for HIV prevention in men who have sex with men. N Engl J Med. 2010.
- Tang et al. 2018. Journal of Acquired Immune Deficiency Syndromes paper on tenofovir disoproxil fumarate and emtricitabine for HIV preexposure prophylaxis.
- Mayer KH et al. Emtricitabine and tenofovir alafenamide versus emtricitabine and tenofovir disoproxil fumarate for HIV pre-exposure prophylaxis. DISCOVER trial. Lancet. 2020.
- Landovitz RJ, et al. Severe lenacapavir injection site nodule. AIDS. 2025;39(10):1486. doi:10.1097/QAD.000000000004271.#10.1097/QAD.000000000004271
- Jogiraju V, et al. Pharmacokinetics and safety of once-yearly lenacapavir: a phase 1, open-label study. Lancet. 2025 Apr 5;405(10485):1147-1154.#10.1016/s0140-6736(25)00405-2
- Molina J-M, et al. Doxycycline post-exposure prophylaxis study (2018).
- Bolan RK, et al. Doxycycline pre-exposure prophylaxis study (2015).
- Luetkemeyer et al. Doxy-PEP / STI prevention study.
- DOXYVAC study.
- dPEP-KE study.
- Moraga et al. Accepted JAAD. DoxyPrEP Pilot Data study.
- Strattman et al. Summary of trials on doxycycline prophylaxis and STI prevention.