Dicloxacillin Dosing and Treatment Duration
For mild to moderate skin and soft tissue infections in adults, dicloxacillin should be dosed at 125-250 mg orally every 6 hours, while severe infections require 500 mg orally every 6 hours, with treatment duration of 7-10 days for uncomplicated cases and at least 14 days for severe staphylococcal infections. 1
Adult Dosing by Infection Type
Mild to Moderate Infections
- Standard dose: 125 mg every 6 hours orally 1
- Impetigo: 250 mg every 6 hours orally for approximately 7 days 2
- Non-purulent cellulitis: 500 mg every 6 hours orally 2
Severe Infections
- Standard dose: 250 mg every 6 hours orally 1
- MSSA skin and soft tissue infections: 500 mg every 6 hours orally 2
- Animal bites (combined with penicillin 500 mg four times daily): 500 mg four times daily 3
Pediatric Dosing (Patients <40 kg)
Mild to Moderate Infections
- 12.5 mg/kg/day divided into 4 equal doses every 6 hours 1
- Impetigo: 12 mg/kg/day divided into 4 doses 2
Severe Infections
- 25 mg/kg/day divided into 4 equal doses every 6 hours 1
- MSSA skin and soft tissue infections: 25-50 mg/kg/day divided into 4 doses 2
Treatment Duration Guidelines
The duration must be tailored to infection severity and clinical response:
- Uncomplicated skin and soft tissue infections: 7-10 days 2
- Impetigo: approximately 7 days, depending on clinical response 2
- Severe staphylococcal infections: at least 14 days 1
- Continue therapy for at least 48 hours after the patient becomes afebrile, asymptomatic, and cultures are negative 1
- Endocarditis and osteomyelitis: longer duration required 1
Critical Administration Instructions
Absorption is significantly affected by food:
- Administer at least 1 hour before or 2 hours after meals on an empty stomach 1
- Take with at least 4 fluid ounces (120 mL) of water 1
- Do not take in the supine position or immediately before going to bed 1
Antimicrobial Spectrum and Limitations
Dicloxacillin is effective only against methicillin-susceptible organisms:
- Active against: Staphylococcus aureus (MSSA), Streptococcus pyogenes, Streptococcus pneumoniae, and Streptococcus epidermidis 2, 4
- Not effective against: MRSA 2
- Misses: Pasteurella multocida in animal bites (hence combination with penicillin) 3
Common Pitfalls to Avoid
Do not use oral dicloxacillin as initial therapy in serious, life-threatening infections - parenteral agents should be used first, with oral therapy reserved for follow-up once clinical condition warrants 1
Avoid in suspected MRSA infections - dicloxacillin has no activity against methicillin-resistant strains and alternative agents (vancomycin, linezolid, daptomycin) must be selected 2
For animal bites, dicloxacillin monotherapy is inadequate - it must be combined with penicillin to cover Pasteurella multocida 3
Pharmacokinetic Considerations
The drug demonstrates predictable linear pharmacokinetics: