Leptospirosis Treatment
For mild-to-moderate leptospirosis, treat adults with doxycycline 100 mg orally twice daily for 7 days, and for severe disease requiring hospitalization, use intravenous penicillin G (1.5 million units every 6 hours) or ceftriaxone 1-2 g daily for 7 days. 1, 2
Treatment by Disease Severity
Mild-to-Moderate (Outpatient) Disease
Adults:
- Doxycycline 100 mg orally twice daily for 7 days (preferred) 1
- Alternative: Amoxicillin 500 mg orally three times daily for 7 days
- Alternative: Azithromycin 500 mg orally once daily for 3 days
Children:
- Amoxicillin 50 mg/kg/day orally in 3 divided doses for 7 days (preferred for children <8 years) 3
- For children ≥8 years: Doxycycline 2-4 mg/kg/day orally in 2 divided doses (maximum 100 mg per dose) for 7 days
The evidence supporting doxycycline comes from a well-designed randomized controlled trial demonstrating it reduced illness duration by 2 days and favorably affected fever, malaise, headache, and myalgias while preventing leptospiruria 1. This makes it the clear first-line choice for adults with mild disease.
Severe Disease (Hospitalized Patients)
Adults:
- Penicillin G 1.5 million units IV every 6 hours for 7 days (traditional first-line)
- Ceftriaxone 1-2 g IV once daily for 7-14 days (increasingly preferred alternative) 2
- Alternative: Cefotaxime 1 g IV every 6 hours for 7 days
Children:
- Crystalline penicillin G is the drug of choice 3
- Dosing: 250,000-400,000 units/kg/day IV divided every 4-6 hours for 7-10 days
- Alternative: Ceftriaxone 50-100 mg/kg IV once daily (maximum 2-4 g/day) for 7-14 days
Key Clinical Considerations
Ceftriaxone advantages over penicillin: A study of 22 patients with severe late leptospirosis treated with ceftriaxone 2g daily showed 21/22 recovered, with superior adverse effect profile and convenience compared to penicillin regimens 2. The once-daily dosing and excellent safety profile make ceftriaxone an increasingly attractive option for severe disease.
Jarisch-Herxheimer Reaction: Be prepared for this reaction within the first 48 hours after initiating antibiotic therapy 4. This is a self-limited inflammatory response and does not indicate treatment failure. Supportive care with antipyretics and hydration is appropriate management.
Treatment Duration: Seven days is the standard duration for both mild and severe disease 1, 2. Some sources suggest extending to 10-14 days for severe cases with organ dysfunction, though evidence for benefit beyond 7 days is limited.
Prophylaxis
For high-risk exposure (e.g., military personnel in endemic areas during training):
- Doxycycline 200 mg orally once weekly during exposure period and for 2 weeks after last exposure 5
A Cochrane review of prophylaxis trials showed doxycycline reduced symptomatic verified leptospirosis from 4.9% to 0.6% (number needed to treat = 24) in soldiers training in endemic areas 5. However, adverse effects occurred in 3% versus 0.2% with placebo (number needed to harm = 39). This prophylaxis strategy is primarily validated for military/occupational settings with high-risk exposure, not routine use in endemic populations.
Special Populations
Pregnant Women:
- Avoid doxycycline
- Use amoxicillin or penicillin-based regimens at standard adult doses
- For severe disease: IV penicillin G or ceftriaxone
Children <8 Years:
- Avoid doxycycline due to teeth staining risk
- Use amoxicillin or penicillin-based regimens as outlined above 3
Common Pitfalls
Delayed treatment: Antibiotics are most effective when started early in the septicemic phase. Late treatment (after day 4-7 of illness) may have limited impact on disease course, though should still be given.
Misdiagnosis: Leptospirosis presents with nonspecific symptoms (fever, headache, myalgias) making diagnosis challenging. Maintain high clinical suspicion in endemic areas, especially with exposure history to contaminated water or animals.
Inadequate supportive care: Severe leptospirosis requires aggressive supportive management including fluid resuscitation, renal replacement therapy if needed, and respiratory support. Antibiotics alone are insufficient for severe disease with organ dysfunction.
Corticosteroid use: Despite theoretical benefits, current evidence does not support routine corticosteroid use in leptospirosis 6. The evidence is of very low certainty and shows no clear benefit on mortality or serious adverse events.