Doxycycline Dosage and Treatment Duration for Bacterial Infections
For most bacterial infections in adults, doxycycline should be administered at 100 mg twice daily for 7-14 days, with the initial day potentially requiring a loading dose of 200 mg (100 mg every 12 hours). 1
Adult Dosing Guidelines
- Standard dosing: 100 mg twice daily (every 12 hours) for most bacterial infections 1
- Initial loading dose: 200 mg on first day (100 mg every 12 hours), followed by maintenance dose of 100 mg daily or 100 mg twice daily depending on infection severity 1
- Severe infections: For more severe infections (particularly chronic urinary tract infections), 100 mg every 12 hours is recommended 1
Specific Infection Types and Duration
Respiratory Infections
- Community-acquired respiratory infections: 100 mg twice daily for 7-10 days 2
- Acute exacerbations of chronic bronchitis: 100 mg twice daily for 10 days 3
Sexually Transmitted Infections
- Uncomplicated gonococcal infections: 100 mg twice daily for 7 days (alternative: single-visit dose of 300 mg followed by another 300 mg one hour later) 1
- Chlamydia trachomatis infections: 100 mg twice daily for 7 days 1
- Nongonococcal urethritis: 100 mg twice daily for 7 days 1
Skin and Soft Tissue Infections (SSTI)
- MRSA skin infections: 100 mg twice daily (duration typically 7-14 days based on clinical response) 4
- General bacterial SSTI: Treatment duration for most bacterial SSTIs should be 7-14 days 4
Other Specific Infections
- Early syphilis: 100 mg twice daily for 2 weeks (for penicillin-allergic patients) 1
- Late syphilis: 100 mg twice daily for 4 weeks (for penicillin-allergic patients) 1
- Acute epididymo-orchitis: 100 mg twice daily for at least 10 days 1
- Tularemia (mild cases): 100 mg twice daily 4
- Bubonic plague: 100 mg twice daily 4
- Bacillary angiomatosis: 100 mg twice daily for 2 weeks to 2 months 4
Special Situations
Anthrax Exposure
- Inhalational anthrax (post-exposure): 100 mg twice daily for 60 days 4, 1
- Cutaneous anthrax: 100 mg twice daily for 60 days 4
Human Granulocytic Anaplasmosis (HGA)
- Standard treatment: 100 mg twice daily for 10 days 4
Pediatric Dosing (children >8 years)
- Standard dosing: 2 mg/lb (4.4 mg/kg) of body weight divided into two doses on the first day, followed by 1 mg/lb (2.2 mg/kg) as a single daily dose or divided into two doses on subsequent days 1
- Severe infections: Up to 2 mg/lb (4.4 mg/kg) of body weight may be used 1
- Children >8 years and >45 kg: Adult dosing (100 mg twice daily) 4
- Children >8 years and ≤45 kg: 2.2 mg/kg every 12 hours 4
Important Considerations and Precautions
- Administration: Take with adequate amounts of fluid to reduce the risk of esophageal irritation and ulceration 1
- Food interaction: Can be taken with food or milk if gastric irritation occurs; absorption is not markedly influenced by simultaneous ingestion of food or milk 1
- Renal impairment: No dosage adjustment needed in patients with renal impairment 1, 5
- Contraindications: Not recommended for children under 8 years of age due to potential for dental staining and bone growth effects 4
- Pregnancy considerations: Generally not recommended during pregnancy but may be used for life-threatening infections; adverse effects on developing teeth and bones are dose-related, so short-term use (7-14 days) before six months of gestation might be considered when benefits outweigh risks 4
- Central nervous system penetration: Doxycycline may be less optimal for meningitis due to poor CNS penetration 4
Advantages of Doxycycline
- Long half-life allowing convenient twice-daily dosing 5
- Well absorbed orally even with food 5
- Excellent tissue penetration 5
- No dose adjustment needed in renal insufficiency 5
- Broad-spectrum activity against many pathogens 5, 2
- Lower doses (20-40 mg/day) may have anti-inflammatory properties in certain conditions 6