What is the recommended dosage and treatment duration of doxycycline for bacterial infections?

Recommended Dosage and Treatment Duration of Doxycycline for Bacterial Infections

The standard dosage of doxycycline for most bacterial infections in adults is 100 mg twice daily (200 mg on day 1, followed by 100 mg every 12 hours), with treatment duration typically ranging from 7-14 days depending on the specific infection type and severity. 1

Adult Dosing Recommendations

Standard Dosing:

• Initial dose: 200 mg on first day (100 mg every 12 hours)
• Maintenance dose: 100 mg daily or 100 mg every 12 hours for more severe infections 1

Specific Infection Types:

• Skin and soft tissue infections: 100 mg twice daily for 7-14 days 2
• Uncomplicated urethral/genital infections:
  • Chlamydia trachomatis: 100 mg twice daily for 7 days 1
  • Nongonococcal urethritis: 100 mg twice daily for 7 days 1
  • Uncomplicated gonorrhea: 100 mg twice daily for 7 days 1
• Syphilis:
  • Early: 100 mg twice daily for 2 weeks (penicillin-allergic patients) 1
  • Late (>1 year duration): 100 mg twice daily for 4 weeks 1
• Acute epididymo-orchitis: 100 mg twice daily for at least 10 days 1
• Respiratory tract infections: 200 mg on first day, followed by 100 mg daily (can continue 200 mg daily in severe cases) 3

Pediatric Dosing (>8 years of age):

• Initial dose: 2 mg/lb (4.4 mg/kg) divided into two doses on first day
• Maintenance dose: 1 mg/lb (2.2 mg/kg) daily as single dose or divided doses
• Severe infections: Up to 2 mg/lb (4.4 mg/kg) daily 1

Special Situations:

Anthrax Exposure (Post-exposure prophylaxis):

• Adults: 100 mg twice daily for 60 days
• Children <100 lbs: 1 mg/lb (2.2 mg/kg) twice daily for 60 days
• Children ≥100 lbs: Adult dose 2, 1

Malaria Prophylaxis:

• Adults: 100 mg daily
• Children >8 years: 2 mg/kg daily (up to adult dose)
• Begin 1-2 days before travel and continue through 4 weeks after leaving malarious area 1

Administration Guidelines:

• Take with adequate fluid to reduce risk of esophageal irritation
• Can be taken with food or milk if gastric irritation occurs
• Food or milk does not markedly influence absorption 1

Important Considerations:

Duration of Treatment:

• Most bacterial infections: 7-14 days 2
• Streptococcal infections: Continue for 10 days to prevent rheumatic fever 1
• Chronic infections: May require longer treatment periods

Contraindications and Cautions:

• Not recommended for children under 8 years due to potential for dental staining 2
• Use with caution in pregnancy (consider alternatives when possible) 2
• Monitor for side effects, particularly gastrointestinal symptoms (nausea, vomiting, diarrhea) 4

Efficacy Considerations:

• Therapeutic serum activity typically persists for 24 hours following recommended dosage 1
• For severe infections, higher doses or longer treatment durations may be necessary
• Current recommended doses (approximately 3.5 mg/kg daily) may not be optimal for all infections 5

Doxycycline remains an effective broad-spectrum antibiotic with good clinical outcomes for many common bacterial infections when used at appropriate dosages and durations.