What is the recommended doxycycline dosing for pediatric patients, including weight‑based dosing, age limits, maximum daily dose, and typical treatment durations?

Doxycycline Pediatric Dosing

For pediatric patients, use weight-based dosing of 2.2 mg/kg every 12 hours (maximum 100 mg per dose) regardless of age, as short-term doxycycline courses do not cause permanent tooth staining even in children under 8 years. 1

Weight-Based Dosing Algorithm

Children < 45 kg (< 100 pounds)

• Loading dose (Day 1): 2 mg/lb (4.4 mg/kg) divided into 2 doses 1
• Maintenance dose (Day 2 onward): 1 mg/lb (2.2 mg/kg) as single daily dose or divided into 2 doses 1
• Alternative dosing: 2.2 mg/kg every 12 hours throughout treatment 1
• Maximum: Do not exceed adult dosing (100 mg per dose) 1

Children ≥ 45 kg (≥ 100 pounds)

• Loading dose (Day 1): 200 mg total (100 mg every 12 hours) 1, 2
• Maintenance dose: 100 mg daily as single dose or 100 mg every 12 hours for serious infections 1, 2

Age Considerations and Safety

All Ages (Including < 8 Years)

• Doxycycline can be used at any age for serious or life-threatening infections 1
• Short-term courses (< 21 days) do not cause permanent tooth staining or enamel hypoplasia in children under 8 years 1
• The historical contraindication was based on older tetracycline data; doxycycline binds less readily to calcium than older tetracyclines 1
• Multiple studies totaling 89 patients treated before age 8 demonstrated zero cases of permanent tooth staining 1

Critical Clinical Context

• Children younger than 10 years are five times more likely to die from Rocky Mountain spotted fever when treatment is delayed 1
• 61-65% of primary care providers incorrectly avoid prescribing doxycycline to children < 8 years, contributing to preventable mortality 1

Condition-Specific Durations

Tickborne Rickettsial Diseases (RMSF, Ehrlichiosis, Anaplasmosis)

• Minimum 5-7 days total 1, 2
• Continue at least 3 days after fever resolves 1, 2

Anthrax Post-Exposure Prophylaxis

• 60 days 1, 2

Chlamydia/Gonorrhea

• 7 days 2

Skin and Soft Tissue Infections

• 7-14 days 3

Maximum Daily Dose

• 200 mg/day (100 mg every 12 hours) for all pediatric patients 1, 2, 3
• This applies regardless of weight once the calculated dose reaches adult dosing 1

Critical Administration Guidelines

Esophageal Protection

• Take with a full glass of water 1, 2
• Remain upright for at least 30 minutes after administration to prevent esophageal irritation and ulceration 1, 2

Drug Interactions to Avoid

• Separate from antacids (aluminum, calcium, magnesium) by 2-3 hours 1, 2
• Separate from iron supplements by 2-3 hours 2
• Separate from dairy products by 2-3 hours if taking on empty stomach 2

Photosensitivity Precautions

• Counsel patients to avoid prolonged sun exposure or UV irradiation 1, 2
• Photosensitivity is a common adverse effect 1

Common Pitfalls to Avoid

• Do not delay treatment in children < 8 years with suspected tickborne rickettsial disease due to outdated tooth staining concerns 1
• Do not substitute chloramphenicol for doxycycline in rickettsial infections, as it is associated with higher mortality and lacks efficacy against ehrlichiosis and anaplasmosis 1
• Avoid prolonged or repeated courses in children < 8 years when possible 2
• Doxycycline has superior safety compared to tetracycline, minocycline, or oxytetracycline, which remain contraindicated in young children 2

Common Adverse Effects

• Gastrointestinal: Nausea, vomiting, diarrhea, esophagitis 1, 2
• Dermatological: Photosensitivity, rash 1
• Rare but serious: Exfoliative dermatitis, Stevens-Johnson syndrome, hepatotoxicity, benign intracranial hypertension 1