Doxycycline Prophylaxis for Leptospirosis Exposure
A single 200 mg oral dose of doxycycline is recommended for prophylaxis of leptospirosis when administered within 72 hours of high-risk exposure. 1
Evidence for Prophylaxis
The recommendation for doxycycline prophylaxis is supported by systematic review evidence showing:
- Doxycycline prophylaxis significantly reduces the risk of developing symptomatic, verified leptospirosis compared to placebo (0.6% vs 4.9%) 1
- The number needed to treat (NNT) is 24, meaning for every 24 people treated with prophylactic doxycycline, one case of leptospirosis is prevented 1
- Doxycycline has been shown to be effective for prevention of several spirochetal infections, including leptospirosis 2
Dosing and Timing
- Dosage: 200 mg as a single oral dose 3, 1
- Timing: Should be administered as soon as possible after exposure but within 72 hours for maximum effectiveness 2
- Administration: Take with food and a full glass of water (8 oz) while remaining upright for at least one hour to prevent esophageal irritation and maximize absorption 4
Indications for Prophylaxis
Prophylaxis should be considered in:
- High-risk exposures in endemic areas 1
- Exposure to potentially contaminated water or soil 3, 5
- Occupational exposures (e.g., military personnel, agricultural workers) 1
- Following adventure activities in fresh water in endemic regions 5
Contraindications and Precautions
Doxycycline is contraindicated in:
- Patients with hypersensitivity to tetracyclines 4
- Children under 8 years of age (risk of dental staining and bone growth effects) 4
- Pregnant or lactating women 4
Adverse Effects
- Adverse effects occur in approximately 3% of patients receiving prophylactic doxycycline 1
- Common side effects include gastrointestinal symptoms (nausea, vomiting, diarrhea) 4
- The number needed to harm (NNH) is 39, meaning for every 39 people treated, one will experience an adverse effect 1
- To minimize gastrointestinal side effects:
- Take with food and plenty of water
- Avoid dairy products, antacids, and supplements with calcium, iron, or magnesium for 2-3 hours before or after the dose 4
Monitoring
- No specific monitoring is required for single-dose prophylaxis
- For those with ongoing exposure risk, reassessment of continued need for prophylaxis may be appropriate 4
Limitations and Considerations
- The evidence primarily comes from studies in military populations, and applicability to other scenarios may vary 1
- Prophylaxis is most effective when combined with preventive measures such as protective clothing and avoiding high-risk exposures 5
- The development of antimicrobial resistance is a potential concern with widespread use 4