How to prescribe doxycycline?

Doxycycline Prescription Guidelines

For adults, doxycycline should be prescribed at 100 mg orally twice daily for most infections, with a loading dose of 200 mg on the first day (administered as 100 mg every 12 hours) followed by a maintenance dose of 100 mg/day. 1

Adult Dosing for Common Indications

Sexually Transmitted Infections

• Chlamydia infection: 100 mg orally twice daily for 7 days 2
• Nongonococcal urethritis: 100 mg orally twice daily for 7 days 2
• Uncomplicated gonorrhea: 100 mg orally twice daily for 7 days 1
  • Alternative single-visit dose: 300 mg stat followed in one hour by a second 300 mg dose 1
• Early syphilis: 100 mg orally twice daily for 2 weeks (for penicillin-allergic patients) 1
• Late syphilis (>1 year duration): 100 mg orally twice daily for 4 weeks (for penicillin-allergic patients) 1

Tick-Borne Diseases

• Human Granulocytic Anaplasmosis (HGA): 100 mg orally twice daily for 10 days 2
• Lyme disease prophylaxis: Single 200 mg dose when all criteria are met:
  1. Identified adult or nymphal Ixodes scapularis tick attached for ≥36 hours
  2. Prophylaxis started within 72 hours of tick removal
  3. Local rate of tick infection with Borrelia burgdorferi ≥20%
  4. No contraindications to doxycycline 2
• Lyme disease treatment: 100 mg orally twice daily for 10-21 days depending on manifestation 2

Skin and Soft Tissue Infections

• Outpatient MRSA skin infections: 100 mg orally twice daily for 5-10 days 2

Other Infections

• Respiratory tract infections: 200 mg on first day, followed by 100 mg daily (can continue 200 mg daily in severe cases) 3
• Malaria prophylaxis: 100 mg orally once daily, starting 1-2 days before travel and continuing through 4 weeks after leaving malarious area 1
• Inhalational anthrax (post-exposure): 100 mg orally twice daily for 60 days 1

Pediatric Dosing

• Children >8 years of age and <45 kg: 2 mg/kg/dose twice daily on first day, then 1-2 mg/kg/dose once or twice daily 1
• Children >8 years and >45 kg: Use adult dosing 1
• Children with HGA: 4 mg/kg/day in 2 divided doses (maximum 100 mg per dose) 2
• Malaria prophylaxis in children >8 years: 2 mg/kg once daily (up to adult dose) 1

Important Administration Guidelines

1. Take with food or milk if gastric irritation occurs, though absorption is not markedly influenced by food 1
2. Administer with adequate fluid to reduce risk of esophageal irritation and ulceration 1
3. Avoid administration within 2 hours of antacids, iron, calcium, magnesium supplements, or dairy products as these can reduce absorption
4. Patient should remain upright for 30 minutes after taking to prevent esophageal irritation

Special Populations

• Renal impairment: No dosage adjustment needed; doxycycline does not accumulate in patients with renal insufficiency 4
• Pregnant women: Generally contraindicated due to potential effects on fetal bone and teeth development, but has been used successfully in specific cases of HGA during pregnancy when benefits outweigh risks 2
• Breastfeeding women: Has been used successfully in specific cases with close monitoring of infant 2

Common Pitfalls and Caveats

1. Avoid in children under 8 years due to risk of dental staining and enamel hypoplasia
2. Photosensitivity reactions are common - advise patients to avoid excessive sunlight exposure and use sunscreen
3. Bacterial resistance development is more likely with high doses (100-200 mg/day) compared to low doses (20-40 mg/day) 5
4. Esophageal ulceration risk - take with full glass of water and remain upright for 30 minutes after administration
5. Compliance issues - consider single-dose regimens (e.g., azithromycin) for patients with anticipated adherence problems

Doxycycline remains a highly effective, broad-spectrum antibiotic with excellent tissue penetration and bioavailability. Its long half-life allows for once or twice daily dosing, making it convenient for patients and potentially improving compliance.