Recommended Doxycycline Dose for Lyme Disease
For adults with early Lyme disease (erythema migrans), doxycycline 100 mg twice daily for 10-14 days is the preferred first-line treatment. 1, 2
Adult Dosing by Disease Stage
Early Localized or Early Disseminated Lyme Disease (Erythema Migrans)
- Doxycycline 100 mg orally twice daily for 10-14 days is the recommended regimen 1, 2
- The 10-day duration is sufficient for doxycycline due to its pharmacokinetic properties 2, 3
- Doxycycline has the added advantage of treating co-infection with Human Granulocytic Anaplasmosis (HGA), which may occur simultaneously 1
Neurologic Manifestations (Meningitis or Radiculopathy)
- Doxycycline 200-400 mg per day orally in 2 divided doses for 10-28 days is an acceptable alternative to intravenous therapy 1
- Doxycycline is well absorbed orally, so intravenous administration is rarely needed 1
- Ceftriaxone 2 g IV once daily for 14 days remains the preferred option for acute neurologic disease, but oral doxycycline has shown comparable efficacy in European studies 1, 4
Pediatric Dosing
Children ≥8 Years of Age
- Doxycycline 4 mg/kg per day in 2 divided doses (maximum 100 mg per dose) for early Lyme disease 1
- For neurologic manifestations: 4-8 mg/kg per day in 2 divided doses (maximum 100-200 mg per dose) for 10-28 days 1
Single-Dose Prophylaxis After Tick Bite
- Doxycycline 4 mg/kg as a single dose (maximum 200 mg) for children ≥8 years when prophylaxis criteria are met 5
- Prophylaxis is only appropriate when: the tick is identified as Ixodes scapularis, attached ≥36 hours, prophylaxis can start within 72 hours of removal, and local infection rate is ≥20% 5
Children <8 Years of Age
- Doxycycline is relatively contraindicated in this age group 1
- However, recent evidence suggests increasing use of doxycycline in younger children, with the American Academy of Pediatrics stating that ≤3 weeks of doxycycline is safe in children of all ages 6
- Alternative first-line agents: amoxicillin 50 mg/kg per day in 3 divided doses (maximum 500 mg per dose) or cefuroxime axetil 30 mg/kg per day in 2 divided doses (maximum 500 mg per dose) 1, 5
Important Administration Guidelines
How to Take Doxycycline
- Administer with 8 ounces of fluid to reduce esophageal irritation 1, 5
- Can be taken with food to reduce gastrointestinal intolerance 1, 5
- Advise patients to avoid sun exposure due to photosensitivity risk 1, 5
Contraindications
- Pregnancy and lactation (relative contraindication) 1
- Children <8 years of age (relative contraindication, though evolving) 1
Critical Pitfalls to Avoid
Ineffective Antibiotics
- First-generation cephalosporins (e.g., cephalexin) are completely ineffective against B. burgdorferi and should never be used 1, 5, 2
- Macrolide antibiotics (azithromycin, clarithromycin, erythromycin) are less effective than doxycycline and should only be reserved for patients intolerant of first-line agents 1, 2
Duration Errors
- Do not extend treatment beyond 14 days for uncomplicated early Lyme disease unless there are objective signs of treatment failure 1, 7
- Studies show no advantage to extending doxycycline from 14 to 20 days for erythema migrans 7
- Avoid prolonged or repeated courses for persistent subjective symptoms without objective findings, as this has not shown benefit and may cause harm 8, 9
Prophylaxis Timing
- **Do not prescribe prophylaxis if the tick was attached <36 hours** or if >72 hours have elapsed since removal, as effectiveness is significantly reduced 5
Alternative First-Line Agents
When doxycycline is contraindicated or not tolerated: