What is the FDA-approved age-based safety dose of doxycycline (tetracycline antibiotic)?

FDA-Approved Age-Based Safety Dosing of Doxycycline

Doxycycline is not recommended for children under 8 years of age due to the risk of dental staining and enamel hypoplasia, but has specific FDA-approved dosing for children 8 years and older based on weight. 1

Adult Dosing

• Standard adult dose: 200 mg on first day (100 mg every 12 hours), followed by 100 mg daily maintenance dose 1
• For severe infections: 100 mg every 12 hours 1

Pediatric Dosing (Children ≥8 years)

• For children weighing ≤100 pounds (45 kg):

  • First day: 2 mg/lb (4.4 mg/kg) of body weight divided into two doses
  • Subsequent days: 1 mg/lb (2.2 mg/kg) of body weight given as single daily dose or divided into two doses 1
  • For severe infections: Up to 2 mg/lb (4.4 mg/kg) of body weight may be used 1

• For children weighing >100 pounds (45 kg):

  • Use standard adult dosing 1

Special Situations

Inhalational Anthrax (Post-exposure)

• Adults: 100 mg twice daily for 60 days 1
• Children <100 lb (45 kg): 1 mg/lb (2.2 mg/kg) twice daily for 60 days 1
• Children ≥100 lb: Adult dose 1

Malaria Prophylaxis

• Adults: 100 mg daily 1
• Children >8 years: 2 mg/kg daily (not exceeding adult dose) 1
• Begin 1-2 days before travel and continue through 4 weeks after leaving malarious area 1

Important Safety Considerations

1. Age restriction: Doxycycline is contraindicated in children under 8 years of age due to risk of permanent tooth discoloration and enamel hypoplasia 2

2. Administration recommendations:

   • Administer with adequate fluids to reduce risk of esophageal irritation and ulceration 1
   • Can be given with food or milk if gastric irritation occurs 1

3. Renal considerations: Unlike other tetracyclines, doxycycline does not require dose adjustment in renal impairment 3

4. Pregnancy and lactation: Doxycycline is a Category D drug and should be avoided during pregnancy and lactation 4

5. Photosensitivity: Patients should be advised about potential photosensitivity reactions and recommended to use sunscreen and avoid direct sun exposure 4

Clinical Pearls

• Doxycycline has better absorption than other tetracyclines even when taken with food 3
• The twice-daily dosing regimen makes it more convenient than other tetracyclines that require more frequent administration 3
• For skin and soft tissue infections, doxycycline is not recommended for persons aged <8 years 2
• When treating bioterrorism-related cutaneous anthrax in children weighing ≥45 kg, the dose is 2.2 mg/kg every 12 hours; for children weighing >45 kg, use 100 mg twice daily 2

By following these FDA-approved age-based dosing guidelines, clinicians can safely prescribe doxycycline while minimizing the risk of adverse effects.