Doxycycline Dosage Recommendations
The standard dosage of doxycycline for adults is 100 mg twice daily (orally or intravenously), with a loading dose of 200 mg on the first day of treatment, followed by a maintenance dose of 100 mg/day for most infections. 1
Adult Dosing
- For most bacterial infections: 100 mg twice daily, or 200 mg on first day followed by 100 mg daily for maintenance 1
- For Human Granulocytic Anaplasmosis (HGA): 100 mg twice daily for 10 days 2
- For sexually transmitted infections:
- For STI post-exposure prophylaxis: 200 mg as a single dose within 72 hours of sexual contact (not to exceed 200 mg per 24 hours) 2
- For malaria prophylaxis: 100 mg once daily 1
Pediatric Dosing
- For children ≥8 years weighing <100 lbs (45 kg): 2.2 mg/kg body weight twice daily 2
- For children ≥8 years weighing ≥100 lbs: Use adult dose 1
- For Human Granulocytic Anaplasmosis in children: 4 mg/kg per day in 2 divided doses (maximum 100 mg per dose) 2
- Doxycycline is generally not recommended for children <8 years of age due to potential dental staining, but may be used when benefits outweigh risks 2
Duration of Treatment
- Respiratory tract infections: Typically 5-7 days 3
- Lyme disease: 10-21 days depending on manifestations 2
- Anaplasmosis: 10 days (to cover potential Lyme disease coinfection) 2
- Tickborne rickettsial diseases: At least 3 days after fever subsides with minimum 5-7 days total 2
- Sexually transmitted infections: 7-14 days depending on the specific infection 1
Administration Guidelines
- Take with adequate fluid (full glass of water) to reduce risk of esophageal irritation 1
- Can be taken with food or milk if gastric irritation occurs 1
- For oral therapy, avoid lying down for at least 1 hour after taking the medication 2
- For severe infections requiring IV therapy, the same dosage is typically used 2
Special Considerations
- For patients with renal impairment: Standard doses generally do not lead to excessive accumulation 1
- For severe infections (particularly chronic urinary tract infections): 100 mg every 12 hours is recommended 1
- For post-exposure prophylaxis for anthrax: 100 mg twice daily for 60 days 1
Common Pitfalls
- Delaying treatment for tickborne diseases while awaiting laboratory confirmation can lead to severe outcomes; empiric therapy should be initiated based on clinical suspicion 2
- Exceeding recommended dosages may increase the incidence of side effects without providing additional benefit 1
- Subtherapeutic dosing may lead to treatment failure; plasma concentrations should be maintained above 1 μg/ml for optimal efficacy 4
- Long-term, high-dose therapy may contribute to bacterial resistance; consider appropriate duration based on the specific infection 5
Always assess the need for continued therapy at appropriate intervals, particularly for chronic conditions requiring extended treatment courses.