What is the recommended dose of doxycycline (antibiotic) for Lyme disease prophylaxis in pediatric patients?

Pediatric Doxycycline Dosing for Lyme Disease Prophylaxis

For children ≥8 years old, a single dose of doxycycline at 4 mg/kg (maximum 200 mg) is recommended for Lyme disease prophylaxis after a high-risk tick bite. 1

Eligibility Criteria for Prophylaxis

Prophylactic treatment with doxycycline should only be offered when ALL of the following conditions are met:

• The tick can be reliably identified as an adult or nymphal Ixodes scapularis tick 1
• The tick is estimated to have been attached for ≥36 hours based on engorgement or known time of exposure 1
• Prophylaxis can be started within 72 hours after tick removal 1
• Local rate of infection of ticks with Borrelia burgdorferi is ≥20% 1
• Doxycycline is not contraindicated for the patient 1

Age-Specific Considerations

• Children ≥8 years old: Single dose of doxycycline at 4 mg/kg (maximum 200 mg) 1, 2
• Children <8 years old: Traditionally, doxycycline was avoided due to concerns about dental staining. However, recent evidence suggests short courses may be safe. If used, the same dosing of 4 mg/kg applies 3, 4

Administration Guidelines

• Administer with adequate fluid (8 ounces) to reduce esophageal irritation 2, 5
• Can be given with food to reduce gastrointestinal intolerance 2, 5
• Advise patients to avoid sun exposure due to photosensitivity risk 2

Treatment Alternatives

When prophylaxis criteria are not met or doxycycline is contraindicated:

• Observation is recommended instead of prophylaxis 1
• For children who develop early Lyme disease (erythema migrans), treatment options include:
  • Amoxicillin: 50 mg/kg/day in 3 divided doses (maximum 500 mg per dose) for 14 days 1, 2
  • Cefuroxime axetil: 30 mg/kg/day in 2 divided doses (maximum 500 mg per dose) for 14 days 1, 2

Evidence Quality and Clinical Considerations

• Doxycycline prophylaxis is supported by high-quality evidence from the Infectious Diseases Society of America guidelines 1
• Recent data suggest doxycycline use in children <8 years is increasing (from 6.9% in 2015 to 67.9% in 2023) 4
• Studies indicate doxycycline is generally well-tolerated in young children, though dental staining remains a theoretical concern 3
• Lyme disease prophylaxis may be underprescribed in children 6

Common Pitfalls to Avoid

• Using first-generation cephalosporins (e.g., cephalexin), which are ineffective against B. burgdorferi 2, 7
• Prescribing prophylaxis when the tick has been attached for less than 36 hours 1
• Delaying prophylaxis beyond 72 hours after tick removal, which reduces effectiveness 1
• Using macrolide antibiotics for prophylaxis, which have lower efficacy 2, 7