Preventative Medication Options for Sexually Transmitted Infections (STIs)
Doxycycline post-exposure prophylaxis (DoxyPEP) is recommended for high-risk populations, particularly cisgender men who have sex with men and transgender women, taken as a 200 mg single dose within 72 hours after condomless sex to prevent bacterial STIs. 1
HIV Prevention Options
Pre-Exposure Prophylaxis (PrEP)
- Daily oral TDF/FTC (tenofovir disoproxil fumarate/emtricitabine) remains the recommended oral PrEP regimen for all populations at risk of HIV exposure (evidence rating: A1a) 1
- PrEP should be discussed and offered to:
- All sexually active persons
- Anyone requesting PrEP
- People who inject drugs or use substances
- Populations with high HIV incidence rates 1
- Long-acting cabotegravir is an injectable PrEP option with follow-up monitoring using rapid HIV antibody and laboratory-based antigen/antibody tests 1
Post-Exposure Prophylaxis (PEP)
- For individuals with known exposure to HIV
- Must be started within 72 hours of exposure
- Typically involves a 28-day course of antiretroviral medications 1
Bacterial STI Prevention
Doxycycline Post-Exposure Prophylaxis (DoxyPEP)
- Dosing: 200 mg taken as a single dose within 72 hours after condomless sex 1
- Effectiveness:
- Reduces syphilis and chlamydia infections by >70%
- Reduces gonococcal infections by approximately 50% 2
- Recommended populations:
- Prescription guidance: Provide 30 doses (60 tablets/capsules) at a time 1
- Monitoring: Quarterly STI screening of contact sites and blood syphilis testing 1
Prophylaxis After Sexual Assault
- Recommended regimen:
- Hepatitis B vaccination should be administered at initial examination with follow-up doses at 1-2 and 4-6 months 1, 2
Viral STI Prevention
Hepatitis B
- Vaccination is the primary preventive measure 1
- Recommended for all unvaccinated patients being evaluated for an STD 1
Hepatitis A
- Vaccination recommended for:
- Men who have sex with men
- Persons who use illegal drugs 1
HPV
- HPV vaccination is recommended as part of comprehensive STI prevention 2
Important Considerations and Monitoring
For DoxyPEP
- Potential side effects: Photosensitivity, esophagitis, gastrointestinal intolerance 1, 2
- Administration guidance: Take with food and plenty of fluid, remain upright for at least 1 hour after taking 2
- Drug interactions: Separate dose by at least 2 hours from dairy products, antacids, and supplements containing calcium, iron, magnesium, or sodium bicarbonate 1
- Reassessment: Evaluate ongoing need for DoxyPEP every 3-6 months 1, 2
For PrEP
- Baseline testing: HIV screening including RNA test and laboratory-based antigen-antibody test 1
- Follow-up: Regular HIV testing and STI screening every 3-6 months 1
- Renal monitoring: TDF-based PrEP is not recommended in persons with creatinine clearance below 60 mL/min/1.73m² 1
Comprehensive Prevention Approach
- Condom use remains a cornerstone of prevention for all penetrative sex acts (evidence rating: AIII) 1
- Regular STI screening at anatomic sites of exposure every 3-6 months 1, 2
- Risk reduction counseling should accompany all preventative medication strategies 1, 2
Common Pitfalls and Caveats
Antimicrobial resistance concerns: The benefit of DoxyPEP in preventing STIs must be weighed against potential development of antimicrobial resistance 3
Limited evidence in certain populations: DoxyPEP efficacy data is strongest for MSM and transgender women; evidence for cisgender women is limited 3
Medication adherence: Effectiveness of preventative medications depends on proper adherence to prescribed regimens 1
False sense of security: Preventative medications should not replace other STI prevention strategies like condom use 1, 2
Viral STIs limitations: Current preventative medications primarily target bacterial STIs and HIV; limited options exist for preventing herpes simplex, human papillomavirus, and other viral STIs 4