What is the recommended dose of doxycycline (antibiotic) for various conditions?

Recommended Doxycycline Dosing for Various Conditions

The standard adult dose of doxycycline is 100 mg twice daily for most infections, with specific dosage adjustments based on the condition being treated, severity of infection, and patient age. 1

Standard Adult Dosing

• Initial dose: 200 mg on the first day (100 mg every 12 hours), followed by a maintenance dose of 100 mg/day for most infections 1
• For more severe infections: 100 mg every 12 hours is recommended 1
• Administration should include adequate fluid (8 ounces) with each dose to reduce esophageal irritation, and can be given with food to reduce gastrointestinal intolerance 2, 1

Pediatric Dosing (Children ≥8 years)

• Initial dose: 2 mg/lb (4.4 mg/kg) of body weight divided into two doses on the first day 1
• Maintenance dose: 1 mg/lb (2.2 mg/kg) of body weight given as a single daily dose or divided into two doses 1
• For more severe infections: Up to 2 mg/lb (4.4 mg/kg) of body weight may be used 1
• For children over 100 lb: Use the standard adult dose 1

Condition-Specific Dosing

Tick-Borne Diseases

• Lyme Disease Prophylaxis: Single dose of 200 mg for adults and 4 mg/kg (maximum 200 mg) for children ≥8 years after high-risk tick bite 3, 2
• Early Lyme Disease: 100 mg twice daily for 10-21 days (adults); 4 mg/kg/day in 2 divided doses for children ≥8 years (maximum 100 mg per dose) 3
• Neurologic Lyme Disease: 200-400 mg/day orally in 2 divided doses for adults; 4-8 mg/kg/day in 2 divided doses for children ≥8 years (maximum 200-400 mg daily) 3
• Human Granulocytic Anaplasmosis (HGA): 100 mg twice daily for 10 days (adults); 4 mg/kg/day in 2 divided doses for children (maximum 100 mg per dose) 3

Sexually Transmitted Infections

• Uncomplicated Gonorrhea: 100 mg twice daily for 7 days, or alternative single visit dose of 300 mg followed by another 300 mg one hour later 1
• Chlamydia Infection: 100 mg twice daily for 7 days 1
• Syphilis (early): 100 mg twice daily for 2 weeks in penicillin-allergic patients 1
• Syphilis (>1 year duration): 100 mg twice daily for 4 weeks in penicillin-allergic patients 1
• Doxycycline PEP for STI Prevention: 200 mg as a single dose within 72 hours after sexual exposure (not to exceed 200 mg per 24 hours) 3

Skin and Soft Tissue Infections

• Methicillin-Susceptible S. aureus (MSSA): 100 mg twice daily orally 3
• Methicillin-Resistant S. aureus (MRSA): 100 mg twice daily orally 3
• Acne: Standard dose of 100 mg daily or twice daily; alternatively, subantimicrobial dose of 20 mg twice daily for moderate acne 4, 5, 6

Other Conditions

• Malaria Prophylaxis: 100 mg daily for adults; 2 mg/kg daily for children >8 years (up to adult dose) 1
• Inhalational Anthrax (post-exposure): 100 mg twice daily for 60 days (adults); 1 mg/lb (2.2 mg/kg) twice daily for 60 days for children <100 lb 1
• Q Fever (acute): 100 mg twice daily for 14 days (adults); 2.2 mg/kg per dose twice daily for children ≥8 years (maximum 100 mg per dose) 3
• Q Fever (chronic): 100 mg twice daily plus hydroxychloroquine 200 mg three times daily for ≥18 months 3

Special Considerations and Precautions

• Pregnancy: Doxycycline is generally contraindicated during pregnancy; alternative agents should be considered 3
• Children <8 years: Generally contraindicated due to potential for dental staining; however, may be used for severe infections when benefits outweigh risks 3
• Administration: Take with adequate fluid and food to reduce gastrointestinal and esophageal irritation; avoid lying down for 1 hour after taking 3, 1
• Photosensitivity: Advise patients to avoid sun exposure due to increased risk of photosensitivity reactions 2
• Duration: Therapeutic serum activity typically persists for 24 hours following recommended dosage 1

Common Pitfalls to Avoid

• Using doxycycline in children <8 years except in specific circumstances where benefits outweigh risks 3
• Inadequate fluid intake with medication, increasing risk of esophageal irritation 1
• Prescribing Lyme disease prophylaxis when tick attachment was <36 hours or when prophylaxis cannot be started within 72 hours of tick removal 2
• Using doses in excess of recommendations, which may increase side effects without improving efficacy 3
• Multiple, repeated courses of antimicrobials for the same episode of Lyme disease 3