What is the recommended dosage of doxycycline (Doxycycline) for extensive folliculitis?

Doxycycline Dosage for Extensive Folliculitis

For extensive folliculitis, treat with doxycycline 100 mg orally twice daily for 7-14 days, with duration based on clinical response and severity of infection. 1, 2

Standard Dosing Regimen

• Adults and children over 100 pounds (45 kg): Doxycycline 100 mg orally twice daily 1, 2
• Children ≥8 years and ≤45 kg: 2.2 mg/kg orally every 12 hours (maximum 100 mg per dose) 2, 3
• First day loading dose option: 200 mg on day 1 (administered as 100 mg every 12 hours), followed by 100 mg daily maintenance 1

Treatment Duration

• Standard course: 7-14 days based on clinical response 1, 2
• The Infectious Diseases Society of America recommends 7-14 days for most bacterial skin and soft tissue infections, including MRSA-associated folliculitis 2
• Continue treatment until inflammatory lesions resolve and no new pustules develop 1

Important Clinical Considerations

Avoid monotherapy: Doxycycline should not be used as monotherapy for acne-related conditions to prevent antibiotic resistance 1

Gram-negative folliculitis: If folliculitis develops after prolonged tetracycline use (3-6 months) or fails to respond to doxycycline, consider gram-negative folliculitis caused by organisms like E. coli, Pseudomonas, or Klebsiella 4. In these cases, isotretinoin 0.5-1 mg/kg daily for 4-5 months is the preferred treatment rather than continuing antibiotics 4

Administration pearls: Patients may take doxycycline with food to minimize gastrointestinal upset, but should avoid dairy products within 2 hours before or after dosing 1

Pediatric Restrictions

• Contraindicated in children <8 years: Due to risk of permanent tooth discoloration and effects on bone growth 2, 3
• Short courses (≤5 days) have not shown significant dental staining, but the effect of 7-14 day courses on permanent tooth discoloration remains uncertain 1

Common Adverse Effects to Monitor

• Gastrointestinal: Nausea, vomiting, diarrhea, esophagitis (most common) 1
• Dermatologic: Photosensitivity reactions, rashes 1, 3
• Other: Vaginal candidiasis in females, rare tremors 1, 5

When to Reassess

• If no clinical improvement occurs within 3-5 days, reconsider the diagnosis 4
• Evaluate for resistant organisms, gram-negative folliculitis, or alternative diagnoses such as fungal infection or non-infectious causes 4
• Consider bacterial culture and sensitivity testing if initial treatment fails 6

Pregnancy Considerations

• Pregnancy Category D: Generally contraindicated in pregnancy due to effects on fetal teeth and bone development 1
• Use only for life-threatening infections where benefits clearly outweigh risks 2