Cephalexin Most Common Concentrations
The most common concentrations of cephalexin are 250 mg and 500 mg capsules for oral administration, with liquid suspensions available as 125 mg/5 mL and 250 mg/5 mL. 1
Standard Formulations
According to FDA labeling, cephalexin is available in the following concentrations 1:
Capsules/Tablets:
- 250 mg
- 333 mg
- 500 mg
- 750 mg
Oral Suspensions:
- 125 mg/5 mL
- 250 mg/5 mL
Most Commonly Used Dosing
The 250 mg and 500 mg oral formulations are the most frequently prescribed based on standard dosing regimens 2, 1:
For Adults:
- 250 mg four times daily (qid) is the usual adult dose for most infections including impetigo 2
- 500 mg four times daily (qid) is used for MSSA skin and soft tissue infections 2
- For certain infections (streptococcal pharyngitis, uncomplicated cystitis), 500 mg every 12 hours may be administered 1
For Pediatric Patients:
- 25-50 mg/kg/day divided into 3-4 doses is the standard pediatric dosing 2, 1
- The liquid suspensions (125 mg/5 mL and 250 mg/5 mL) are most commonly used in children to allow weight-based dosing
Clinical Context
The 250 mg and 500 mg formulations dominate clinical practice because they align with the FDA-approved adult dosage range of 1-4 grams daily in divided doses 1. The IDSA guidelines for skin and soft tissue infections consistently reference these two strengths across multiple infection types 2.
The liquid suspensions are essential for pediatric dosing, with the 250 mg/5 mL concentration allowing more precise weight-based administration for larger children while the 125 mg/5 mL is used for smaller children 1.