Sexually Transmitted Diseases Treated by Doxycycline
Doxycycline effectively treats several sexually transmitted diseases (STDs) including chlamydia, syphilis, and lymphogranuloma venereum (LGV), and can be used as postexposure prophylaxis to prevent these infections along with some protection against gonorrhea.
Primary STD Indications for Doxycycline
Chlamydia Infections
- First-line treatment for uncomplicated urethral, endocervical, or rectal infections caused by Chlamydia trachomatis 1
- Highly effective for chlamydial infections with cure rates exceeding 95%
- Standard dosage: 100 mg orally twice daily for 7 days
Syphilis
- Alternative treatment for syphilis caused by Treponema pallidum when penicillin is contraindicated 1
- Used in non-pregnant patients with severe penicillin allergy
- Dosage: 100 mg orally twice daily for 14-28 days (depending on stage)
Lymphogranuloma Venereum (LGV)
- Preferred treatment for LGV caused by specific serovars of C. trachomatis 2
- Recommended regimen: 100 mg orally twice daily for 21 days
- Treats infection and prevents ongoing tissue damage, though scarring may still occur
Other STD-Related Uses
Gonorrhea
- Not a first-line treatment for gonorrhea due to increasing antimicrobial resistance 2
- May be used as an alternative when other options are unavailable
- Still effective against some strains of N. gonorrhoeae in the United States
- When used as postexposure prophylaxis, provides approximately 50% reduction in gonococcal infections 2
Nongonococcal Urethritis
- Effective for nongonococcal urethritis caused by Ureaplasma urealyticum 1
- Standard dosage: 100 mg orally twice daily for 7 days
Emerging Role in STD Prevention
Doxycycline Post-Exposure Prophylaxis (Doxy-PEP)
- CDC now recommends doxycycline as postexposure prophylaxis for certain high-risk populations 2
- Specifically for men who have sex with men (MSM) and transgender women who have had a bacterial STI in the past 12 months
- Dosage: 200 mg taken within 72 hours after condomless sex
- Reduces bacterial STI incidence by approximately two-thirds 3
- Most effective for preventing chlamydia (88% reduction) and syphilis (87% reduction)
- Less effective but still beneficial for gonorrhea (57% reduction)
Clinical Considerations
Contraindications
- Contraindicated in pregnancy - pregnant women should use alternative treatments such as penicillin or erythromycin 2
- Not recommended for children under 8 years due to potential dental discoloration
Side Effects
- Common: photosensitivity, gastrointestinal symptoms
- More serious but less common: esophageal erosion and ulceration 2
- Most adverse effects resolve with discontinuation of the medication
Treatment Duration
- Standard treatment duration varies by infection:
- Chlamydia: 7 days
- Syphilis: 14-28 days (depending on stage)
- LGV: 21 days (though some evidence suggests 7-14 days may be effective in most cases) 4
Follow-Up Recommendations
- For LGV: Patients should be followed clinically until signs and symptoms have resolved 2
- For doxy-PEP users: Bacterial STI testing at anatomic sites of exposure at baseline and every 3-6 months 2
- Regular assessment of ongoing need for prophylaxis every 3-6 months
Partner Management
- Sexual contacts of patients with STDs treated with doxycycline should be examined and tested
- For LGV specifically: Examine and treat partners who had contact within 30 days before symptom onset 2
Doxycycline remains a valuable antibiotic in the management of several STDs due to its efficacy, good tolerability, oral administration, and relatively low cost 5. Its broad-spectrum activity makes it particularly useful for treating infections caused by intracellular pathogens common in STDs.