What is the recommended dose of doxycycline (Doxycycline) for the treatment of scrub typhus?

Doxycycline Dosing for Scrub Typhus

For adults with scrub typhus, administer doxycycline 100 mg twice daily (orally or intravenously) for at least 3 days after fever subsides, with a minimum total treatment course of 5-7 days. 1, 2

Adult Dosing

• Standard dose: 100 mg twice daily (oral or IV) 1, 2
• Continue treatment for at least 3 days after defervescence 1, 2
• Minimum total course: 5-7 days 1, 2
• Severe or complicated disease may require longer treatment courses 1

Pediatric Dosing

Children Under 45 kg

• Loading dose: 4.4 mg/kg as a single dose 2
• Maintenance dose: 2.2 mg/kg every 12 hours 1, 2
• Continue for at least 3 days after fever subsides 1

Children 45 kg or Above

• Loading dose: 200 mg as a single dose 2
• Maintenance dose: 100 mg every 12 hours 2
• Same duration principles as adults 1

Route of Administration

• Oral therapy is appropriate for mild disease in outpatients 1
• Intravenous therapy should be used for severely ill patients requiring hospitalization 1
• Both routes provide similar bioavailability 3

Critical Treatment Principles

Timing of Initiation

• Start treatment immediately upon clinical suspicion—never delay for laboratory confirmation 2
• Delaying treatment can lead to severe disease, long-term sequelae, or death 2
• Early use of doxycycline reduces complications and mortality 4

Expected Clinical Response

• Patients typically respond within 24-48 hours of appropriate antibiotic therapy 2
• If fever persists beyond 48 hours, consider alternative diagnoses or resistant infection 1
• Median time to defervescence is approximately 21-29 hours 5

Common Pitfalls to Avoid

Underdosing in Children

• Always calculate doses based on actual body weight, not age alone 2
• Verify syrup concentration before calculating mL doses to avoid errors 2

Dental Staining Concerns

• The historical concern about dental staining in children under 8 years should not prevent doxycycline use for scrub typhus 1, 2
• The benefits of treatment far outweigh the minimal risk of tooth discoloration with short-term therapy 1

Premature Discontinuation

• Do not stop treatment when fever resolves—continue for at least 3 additional days 1, 2
• Inadequate treatment duration may lead to relapse, though this is rare with appropriate courses 6

Alternative Agents

If doxycycline cannot be used:

• Chloramphenicol: 12.5-25 mg/kg every 6 hours IV (maximum 1 g/dose) 2
• Azithromycin is recommended for pregnancy and children when doxycycline is contraindicated 7
• Rifampin 600 mg once daily for 5 days shows equivalent efficacy to doxycycline and may be considered in areas with doxycycline resistance 7, 8

Monitoring Requirements

• Close follow-up for outpatients to ensure appropriate response to therapy 1
• Monitor for defervescence as the primary indicator of treatment success 1
• Assess for clinical improvement including resolution of headache, myalgia, and rash 8