| Penicillin G |
| Adult dose: 20-24 million U/d IM divided q4-6h |
| Pediatric dose |
| - Children under lbs: 600,000 U IM |
| - Children from 30 to 50 lbs: 900,000 to 1.2 million U IM |
| - Children over 50 lbs: Administer as in adults |
| Crystalline penicillin |
| Dosage: 6-8 megaunits/day divided IV and IM |
| Procaine penicillin and crystalline penicillin |
| Beginning dosage: 2-2.5 megaunits/day each IM |
| Reduce to 1-1.2 megaunits/day each IM when fever reduces, totaling a 5-7 days course |
| Then 1.5 megaunits/day of procaine penicillin until 2 days after cessation of albuminuria |
| Erythromycin |
| Adult dose: 500 mg IV QID |
| Pediatric dose: 30-50 mg/kg/d in 3-4 divided doses |
| Amoxicillin |
| Adult dose: 500 mg PO QID |
| Alternatively: 1 g IV if severe leptospirosis |
| Pediatric dose: 20-40 mg/kg/day |
| Ampicillin |
| Adult dose: 500-750 mg PO QID |
| Alternatively: 1 g if severe leptospitosis |
| Pediatric dose: 50 mg/kg/day |
| Doxycycline |
| Adult dose: 100 mg PO BID |
| Pediatric dose: |
| - Children under 8 years: Not recommended |
| - Children over 8 years: 2 mg/lb PO divided BID on first day, followed by 1 mg/lb/d qd or divided BID on subsequent days |
| Pre-exposure prophylaxis: 200 mg once per week (95% efficacy against leptospirosis[11] |
| Post-exposure prophylaxis: 100 mg per day for 7 days |
| Tetracycline |
| Initial dose of 500 mg |
| 250 mg every 8 h, PO, IV or IM for 24 h |
| Then, 250-500 mg QID for 6 days |
| Caftriaxone |
| 1.0 g q 24 h for 7 days |
