What is the recommended treatment for chlamydia, a sexually transmitted infection (STI)?

Chlamydia Treatment

First-Line Treatment

For uncomplicated chlamydia, treat with either azithromycin 1 g orally as a single dose OR doxycycline 100 mg orally twice daily for 7 days—both achieve 97-98% cure rates and are equally effective. 1, 2

Choosing Between First-Line Options

• Azithromycin 1 g single dose is preferred when:

  • Compliance with multi-day regimens is questionable 1
  • Directly observed therapy is needed 1
  • Follow-up is unpredictable 1
  • Patient has erratic health-care-seeking behavior 1

• Doxycycline 100 mg twice daily for 7 days is preferred when:

  • Cost is a primary concern (doxycycline is less expensive) 1, 2
  • Patient can reliably complete 7-day therapy 2

Dosing Details

• Azithromycin: 1 g orally as a single dose (97% efficacy) 1, 2
• Doxycycline: 100 mg orally twice daily for 7 days (98% efficacy) 1, 2, 3

Alternative Treatment Options

Use these only when first-line options cannot be used due to allergy or intolerance 1:

• Erythromycin base 500 mg orally four times daily for 7 days 1, 2, 4
• Erythromycin ethylsuccinate 800 mg orally four times daily for 7 days 1, 2
• Ofloxacin 300 mg orally twice daily for 7 days 1, 2
• Levofloxacin 500 mg orally once daily for 7 days (88-94% efficacy—lower than first-line) 1

Important caveat: Erythromycin has poor compliance due to gastrointestinal side effects and lower efficacy than azithromycin or doxycycline 1, 2

Treatment During Pregnancy

Azithromycin 1 g orally as a single dose is the preferred treatment during pregnancy. 1

• Alternative: Amoxicillin 500 mg orally three times daily for 7 days 1, 2
• Second alternative: Erythromycin base 500 mg orally four times daily for 7 days 1, 4
• Absolutely contraindicated: Doxycycline, ofloxacin, levofloxacin, and all fluoroquinolones 1

Pregnant women always require test-of-cure 3-4 weeks after treatment completion due to use of alternative regimens with lower efficacy 1

Pediatric Dosing

Children ≥8 years weighing >45 kg:

• Azithromycin 1 g orally as a single dose OR
• Doxycycline 100 mg orally twice daily for 7 days 1

Children ≥8 years weighing <45 kg:

• Erythromycin base or ethylsuccinate 50 mg/kg/day orally divided into four doses daily for 14 days 1

Infants with chlamydial pneumonia (1-3 months):

• Erythromycin base or ethylsuccinate 50 mg/kg/day orally divided into four doses daily for 14 days (80% effective; may need second course) 1

Do NOT use non-culture tests (EIA, DFA) in children—high risk of false-positives from cross-reaction with other organisms 1

Implementation Best Practices

• Dispense medications on-site when possible and directly observe the first dose to maximize compliance 1, 2
• Patients must abstain from all sexual intercourse for 7 days after initiating treatment and until all sex partners are treated 1
• Administer doxycycline with adequate fluids to reduce risk of esophageal irritation and ulceration 3
• If gastric irritation occurs with doxycycline, give with food or milk (absorption not significantly affected) 3

Partner Management

All sex partners from the previous 60 days must be evaluated, tested, and empirically treated to prevent reinfection 1, 2

• If last sexual contact was >60 days before diagnosis, still treat the most recent partner 1
• Failing to treat sex partners leads to reinfection in up to 20% of cases 1

Concurrent STI Testing and Treatment

• Test all patients for gonorrhea, syphilis, and HIV at initial visit 1
• If gonorrhea is confirmed or prevalence is high, always treat chlamydia concurrently due to high coinfection rates 1
• Consider HPV vaccination referral, smoking cessation counseling, and influenza vaccine 1

Follow-Up and Test-of-Cure

Test-of-Cure (3-4 weeks post-treatment):

• NOT recommended for non-pregnant patients treated with recommended regimens (azithromycin or doxycycline) due to 97-98% cure rates 1
• Testing before 3 weeks is unreliable—nucleic acid amplification tests yield false-positives from dead organisms 1
• Perform test-of-cure only if:
  • Questionable therapeutic compliance 1
  • Persistent symptoms 1
  • Suspected reinfection 1
  • Patient is pregnant (always required) 1

Reinfection Screening (3 months post-treatment):

• All women with chlamydia must be retested approximately 3 months after treatment regardless of whether partners were reportedly treated 1
• Reinfection rates reach up to 39% in some adolescent populations 1
• Repeat infections carry elevated risk for pelvic inflammatory disease and complications compared to initial infection 1
• Men may also benefit from retesting at 3 months, though evidence is more limited 1

Special Considerations for Rectal Chlamydia

For rectal chlamydia, doxycycline 100 mg twice daily for 7 days is strongly preferred over azithromycin 5

• Azithromycin efficacy for rectal chlamydia is only 82.9% (95% CI 76.0%-89.8%) 5
• Doxycycline efficacy for rectal chlamydia is 99.6% (95% CI 98.6%-100%) 5
• This represents a 19.9% efficacy difference favoring doxycycline 5

Common Clinical Pitfalls

• Do NOT wait for test results if compliance with return visit is uncertain in high-prevalence populations—treat presumptively 1
• Do NOT use levofloxacin as first-line therapy—it lacks clinical trial data for chlamydia and offers no compliance benefit over doxycycline 1
• Do NOT assume azithromycin and doxycycline are equivalent for rectal chlamydia—doxycycline is significantly more effective 5
• Do NOT forget to warn patients taking metronidazole (if treating concurrent bacterial vaginosis) to avoid alcohol during treatment and for 24 hours afterward 6