Doxycycline Dosage and Treatment Duration for Bacterial Infections
For most bacterial infections, doxycycline should be administered at a dose of 100 mg twice daily for 7-14 days, with specific durations based on the infection type. 1, 2
Standard Adult Dosing
- Initial dose: 200 mg on the first day (100 mg every 12 hours) followed by a maintenance dose of 100 mg/day for most infections 2
- For more severe infections (particularly chronic urinary tract infections), 100 mg every 12 hours is recommended 2
- Administration should be with adequate amounts of fluid to reduce the risk of esophageal irritation and ulceration 2
- Taking with food or milk is recommended if gastric irritation occurs, although this does not markedly influence absorption 2
Infection-Specific Dosing and Duration for Adults
Skin and Soft Tissue Infections
- MRSA skin infections: 100 mg twice daily for 7-14 days based on clinical response 1
- Most bacterial skin and soft tissue infections: 7-14 days of treatment 1
Sexually Transmitted Infections
- Uncomplicated gonococcal infections: 100 mg twice daily for 7 days (alternative: single visit dose of 300 mg followed by another 300 mg one hour later) 2
- Chlamydia trachomatis infections (urethral, endocervical, or rectal): 100 mg twice daily for 7 days 2
- Nongonococcal urethritis: 100 mg twice daily for 7 days 2
Other Specific Infections
- Early syphilis (in penicillin-allergic patients): 100 mg twice daily for 2 weeks 2
- Syphilis of more than one year's duration: 100 mg twice daily for 4 weeks 2
- Acute epididymo-orchitis caused by N. gonorrhoeae or C. trachomatis: 100 mg twice daily for at least 10 days 2
- Tularemia, bubonic plague, and bacillary angiomatosis: 100 mg twice daily 1
Special Situations
- Inhalational anthrax (post-exposure): 100 mg twice daily for 60 days 2, 1
- Cutaneous anthrax: 100 mg twice daily for 60 days 1
- Malaria prophylaxis: 100 mg daily, beginning 1-2 days before travel to malarious area, continuing during travel and for 4 weeks after leaving 2
Pediatric Dosing
- For children over 8 years of age weighing ≤100 pounds: 2 mg/lb of body weight divided into two doses on the first day, followed by 1 mg/lb as a single daily dose or divided into two doses on subsequent days 2
- For more severe infections: up to 2 mg/lb of body weight may be used 2
- For children over 8 years and over 45 kg (or >100 pounds): adult dosing (100 mg twice daily) 1, 2
- For children over 8 years and ≤45 kg: 2.2 mg/kg every 12 hours 1, 3
Important Considerations and Precautions
- Doxycycline is traditionally not recommended for children under 8 years of age due to potential for dental staining and bone growth effects 1, 4
- However, it can be used in children under 8 years when benefits outweigh risks, particularly for serious infections such as Rocky Mountain Spotted Fever and other life-threatening conditions 3
- Doxycycline may be used during pregnancy for life-threatening infections, but its use should be carefully considered due to potential adverse effects on developing teeth and bones 1
- Common adverse effects include gastrointestinal symptoms (nausea, vomiting, diarrhea, esophagitis) and photosensitivity 3
- Take with a full glass of water and avoid lying down for 1 hour after taking to prevent esophagitis 5
- Avoid co-administration with antacids containing aluminum, calcium, or magnesium (take doxycycline at least 2-3 hours before or after) 3
Special Clinical Situations
- For streptococcal infections, therapy should be continued for 10 days 2
- Low doses (20-40 mg/day) have been studied for anti-inflammatory properties but are not standard for treating bacterial infections 6
- Doxycycline has shown promise in treating multidrug-resistant Gram-negative bacterial infections, with clinical improvement achieved in 81.3% of patients in limited studies 7