Doxycycline Dosing for Bacterial Skin Infections in Adults
For adult patients with bacterial skin infections, the recommended dosage of doxycycline is 100 mg orally twice daily for 7-14 days. 1, 2, 3
Standard Dosing Regimen
- The FDA-approved dosing is 200 mg on the first day (administered as 100 mg every 12 hours), followed by a maintenance dose of 100 mg daily 3
- However, for skin and soft tissue infections, the IDSA guidelines recommend 100 mg twice daily (bid) throughout the treatment course 1, 2
- Treatment duration should be 7-14 days depending on clinical response and infection severity 1, 2
Clinical Context and Pathogen Coverage
- Doxycycline is bacteriostatic and has limited recent clinical experience for skin infections, but remains a guideline-recommended option 1
- It provides excellent activity against Eikenella species, staphylococci, and anaerobes, though some streptococci may be resistant 1, 2
- For MRSA skin and soft tissue infections (SSTIs), doxycycline is an effective oral treatment option 1, 2
- The IDSA strongly recommends tetracyclines as oral treatment options for purulent SSTIs, especially when MRSA is of clinical concern 4
Important Dosing Considerations
Severe Infections
- For more severe infections, particularly chronic urinary tract infections, 100 mg every 12 hours is recommended rather than the reduced maintenance dose 3
- This higher dosing (100 mg bid) should be applied to serious skin infections as well 1, 2
Pediatric Contraindication
- Doxycycline is NOT recommended for children under 8 years of age due to risk of permanent tooth discoloration and enamel hypoplasia 1, 2, 3
Administration
- Administer with adequate fluids to reduce risk of esophageal irritation and ulceration 3
- If gastric irritation occurs, give with food or milk—absorption is not significantly affected 3
- No dosage adjustment required for renal impairment 2, 3
Common Pitfalls to Avoid
- Do not use subantimicrobial doses (20-40 mg) for active bacterial skin infections—these doses are only for acne or rosacea and lack antimicrobial activity 5, 6, 7
- Do not reduce to 100 mg once daily for active infections—this maintenance dose is insufficient for bacterial eradication in SSTIs 1, 3
- Ensure full 7-day minimum course—inadequate duration leads to treatment failure 2
- Exceeding recommended dosage may result in increased incidence of side effects 3
Special Clinical Scenarios
Bite Wounds
- For animal or human bite infections, doxycycline 100 mg bid orally or 100 mg every 12 hours IV is recommended 1
- Note: Doxycycline has excellent activity against Pasteurella multocida but some streptococci are resistant 1
Necrotizing Infections
- For life-threatening necrotizing infections caused by Aeromonas hydrophila or Vibrio vulnificus, use doxycycline 100 mg every 12 hours IV plus ciprofloxacin or ceftriaxone 1
- This combination therapy is critical for mortality reduction in these severe infections 1