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Cephalexin Dosage

Medically reviewed on April 18, 2017.

Applies to the following strengths: 250 mg; 500 mg; 125 mg/5 mL; 250 mg/5 mL; 333 mg; hydrochloride 500 mg; 125 mg; 750 mg

Usual Adult Dose for Otitis Media

250 to 333 mg orally every 6 hours OR 500 mg orally every 12 hours
-Maximum dose: 4 g per day
-Duration of therapy: 7 to 14 days

Use: Treatment of otitis media caused by susceptible Streptococcus pneumoniae, Haemophilus influenzae, Staphylococcus aureus, Streptococcus pyogenes, and Moraxella catarrhalis

Usual Adult Dose for Pharyngitis

250 to 333 mg orally every 6 hours OR 500 mg orally every 12 hours
-Maximum dose: 4 g per day
-Duration of therapy: 7 to 14 days

Use: Treatment of skin and skin structure infections caused by susceptible gram-positive bacteria (e.g., S aureus, S pyogenes)

IDSA Recommendations:
Skin or soft tissue infections: 500 mg orally 4 times a day

Impetigo: 250 mg orally 4 times a day

Pharyngitis: 20 mg/kg orally 2 times a day
-Maximum dose: 500 mg/dose
-Duration of therapy: 10 days

Uses:
-Empirical treatment for nonpurulent cellulitis and diabetic foot infections caused by beta-hemolytic streptococci (e.g., methicillin-susceptible Staphylococcus aureus [MSSA], Streptococcus species)
-Treatment of skin or soft tissue infections caused by MSSA in patients who have penicillin allergies (except immediate hypersensitivity)
-Treatment of impetigo caused by Staphylococcus and Streptococcus species
-Treatment of Group A streptococcal pharyngitis in patients with penicillin allergy (except immediate hypersensitivity)
-Treatment of surgical site infections of the trunk/extremity away from the perineum or axilla

Usual Adult Dose for Skin or Soft Tissue Infection

250 to 333 mg orally every 6 hours OR 500 mg orally every 12 hours
-Maximum dose: 4 g per day
-Duration of therapy: 7 to 14 days

Use: Treatment of skin and skin structure infections caused by susceptible gram-positive bacteria (e.g., S aureus, S pyogenes)

IDSA Recommendations:
Skin or soft tissue infections: 500 mg orally 4 times a day

Impetigo: 250 mg orally 4 times a day

Pharyngitis: 20 mg/kg orally 2 times a day
-Maximum dose: 500 mg/dose
-Duration of therapy: 10 days

Uses:
-Empirical treatment for nonpurulent cellulitis and diabetic foot infections caused by beta-hemolytic streptococci (e.g., methicillin-susceptible Staphylococcus aureus [MSSA], Streptococcus species)
-Treatment of skin or soft tissue infections caused by MSSA in patients who have penicillin allergies (except immediate hypersensitivity)
-Treatment of impetigo caused by Staphylococcus and Streptococcus species
-Treatment of Group A streptococcal pharyngitis in patients with penicillin allergy (except immediate hypersensitivity)
-Treatment of surgical site infections of the trunk/extremity away from the perineum or axilla

Usual Adult Dose for Osteomyelitis

250 to 333 mg orally every 6 hours OR 500 mg orally every 12 hours
-Maximum dose: 4 g per day
-Duration of therapy: 7 to 14 days

Use: Treatment of bone infections caused by susceptible S aureus and Proteus mirabilis

Usual Adult Dose for Cystitis

250 to 333 mg orally every 6 hours OR 500 mg orally every 12 hours
-Maximum dose: 4 g per day
-Duration of therapy: 7 to 14 days

Use: Treatment of genitourinary tract infections caused by susceptible Escherichia coli, P mirabilis, and Klebsiella pneumoniae

Usual Adult Dose for Prostatitis

250 to 333 mg orally every 6 hours OR 500 mg orally every 12 hours
-Maximum dose: 4 g per day
-Duration of therapy: 7 to 14 days

Use: Treatment of genitourinary tract infections caused by susceptible Escherichia coli, P mirabilis, and Klebsiella pneumoniae

Usual Adult Dose for Pyelonephritis

250 to 333 mg orally every 6 hours OR 500 mg orally every 12 hours
-Maximum dose: 4 g per day
-Duration of therapy: 7 to 14 days

Use: Treatment of genitourinary tract infections caused by susceptible Escherichia coli, P mirabilis, and Klebsiella pneumoniae

Usual Adult Dose for Upper Respiratory Tract Infection

250 to 333 mg orally every 6 hours OR 500 mg orally every 12 hours
-Maximum dose: 4 g per day
-Duration of therapy: 7 to 14 days

Use: Treatment of respiratory tract infections caused by susceptible S pneumoniae and S pyogenes

Usual Adult Dose for Bacterial Endocarditis Prophylaxis

American Heart Association (AHA) and Infectious Diseases Society of America (IDSA) Recommendations: 2 g orally as a single dose 30 to 60 minutes before the procedure

Use: Prevention of infective endocarditis in patients allergic to penicillins/ampicillins undergoing a dental procedure (except in immediate hypersensitivity)

Usual Adult Dose for Bacterial Infection

IDSA Recommendations: 500 mg orally 3 to 4 times a day

Uses:
-Preferred antimicrobial for chronic suppression of oxacillin-susceptible staphylococci
-Alternative antimicrobial for chronic suppression of beta-hemolytic streptococci or Propionibacterium species

Usual Pediatric Dose for Otitis Media

12.5 to 25 mg/kg orally every 6 hours

Usual Pediatric Dose for Pharyngitis

Over 1 year of age:
Streptococcal pharyngitis: 12.5 to 25 mg/kg orally every 12 hours

Usual Pediatric Dose for Skin or Soft Tissue Infection

12.5 to 25 mg/kg orally every 12 hours

Usual Pediatric Dose for Upper Respiratory Tract Infection

1 to 15 years:
Mild to moderate infections: 25 to 50 mg/kg orally per day, given in equally divided doses
Severe infections: 50 to 100 mg/kg orally per day, given in equally divided doses
Duration of therapy: 7 to 14 days

15 years and older: 250 to 333 mg orally every 6 hours OR 500 mg orally every 12 hours
-Maximum dose: 4 g per day
-Duration of therapy: 7 to 14 days

Comment: Beta-hemolytic streptococcal infections should be treated for at least 10 days.

Use: Treatment of respiratory tract infections caused by susceptible S pneumoniae and S pyogenes

Pediatric Infectious Diseases Society (PIDS) and IDSA Recommendations:
Greater than 3 months:
Step-down therapy or mild infection: 75 to 100 mg/kg orally per day, in 3 to 4 divided doses

Use: Preferred treatment of community acquired pneumonia caused by MSSA

Usual Pediatric Dose for Osteomyelitis

15 years and older: 250 to 333 mg orally every 6 hours OR 500 mg orally every 12 hours
-Maximum dose: 4 g per day
-Duration of therapy: 7 to 14 days

Use: Treatment of bone infections caused by susceptible S aureus and P mirabilis

Usual Pediatric Dose for Cystitis

15 years and older: 250 to 333 mg orally every 6 hours OR 500 mg orally every 12 hours
-Maximum dose: 4 g per day
-Duration of therapy: 7 to 14 days

Use: Treatment of genitourinary tract infections caused by susceptible E coli, P mirabilis, and K pneumoniae

Usual Pediatric Dose for Prostatitis

15 years and older: 250 to 333 mg orally every 6 hours OR 500 mg orally every 12 hours
-Maximum dose: 4 g per day
-Duration of therapy: 7 to 14 days

Use: Treatment of genitourinary tract infections caused by susceptible E coli, P mirabilis, and K pneumoniae

Usual Pediatric Dose for Pyelonephritis

15 years and older: 250 to 333 mg orally every 6 hours OR 500 mg orally every 12 hours
-Maximum dose: 4 g per day
-Duration of therapy: 7 to 14 days

Use: Treatment of genitourinary tract infections caused by susceptible E coli, P mirabilis, and K pneumoniae

Usual Pediatric Dose for Bacterial Infection

American Academy of Pediatrics (AAP) Recommendations:
Children (Older than neonates):
-Mild to moderate infection: 25 to 50 mg/kg orally in 2 to 4 doses
-Severe infection: 75 to 100 mg/kg orally in 3 to 4 doses

Comment: Current guidelines should be consulted for additional information.

Usual Pediatric Dose for Bacterial Endocarditis Prophylaxis

AHA and IDSA Recommendations: 50 mg/kg orally as a single dose 30 to 60 minutes before the procedure

Use: Prevention of infective endocarditis in patients allergic to penicillins/ampicillins undergoing a dental procedure (except in immediate hypersensitivity)

Renal Dose Adjustments

15 years and older:
CrCl 30 to 59 mL/min: The maximum daily dose is 1 g.
CrCl 15 to 29 mL/min: 250 mg orally every 8 to 12 hours
CrCl 5 to 14 mL/min: 250 mg orally every 24 hours
CrCl 1 to 4 mL/min: 250 mg orally every 48 to 60 hours

Liver Dose Adjustments

Data not available

Precautions

Safety and efficacy have not been established in patients younger than 1 years.

Consult WARNINGS section for additional precautions.

Dialysis

Data not available

Other Comments

Administration advice:
-This drug may be taken with or without food.
-Tablets and capsules should be taken with a full glass of water.

Storage requirements:
-Capsules: Protect from light and moisture.
-Oral suspension: Store in the refrigerator (2 to 8C) when not in use.

General:
-Limitation of use: This drug should not be used to treat patients with severe systemic infections during the acute phase.
-This drug may be preferred to other antibiotics in pediatric patients due to increased tolerability and palatability.

Monitoring:
-Hematologic: Prothrombin time (especially in patients at risk of prolonged prothrombin time)
-Renal: Renal function (especially in patients with renal dysfunction)

Patient advice:
-Patients should be told to report any unusual or severe side effects.
-Patients should be instructed to report signs/symptoms of Clostridium difficile (e.g., watery/bloody stools, stomach cramps, fever), for up to 2 months after stopping treatment.
-Patients should be directed to take the full course of treatment, even if they feel better.
-Patients receiving the oral suspension/syrup formulations should be told to discard any remaining drug at the end of the duration of therapy.

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

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