Cephalexin Dosages

Cephalexin is an antibiotic used to treat various bacterial infections. Understanding the correct dosage is crucial for its effectiveness and safety. Below, we provide detailed information on Cephalexin dosage, including recommendations for different conditions, age groups, and renal adjustments.

Visit our in-depth articles for an overview of Cephalexin’s Uses and how it compares to other antibiotics.

Cephalexin is available in various forms, including capsules, tablets, and oral suspensions.

For example, mild infections may require lower doses, while more severe infections or resistant bacteria might necessitate higher or more frequent dosing. Ensure you purchase the correct dosage as prescribed by your doctor. Taking the wrong dosage can lead to ineffective treatment or antibiotic resistance. Learn more about Different Forms of Cephalexin.

Dosage for Adults

Below, you will find the standard adult dosages for different conditions.

Otitis Media

• 250 to 333 mg taken orally every 6 hours, or 500 mg taken orally every 12 hours.
• Maximum dosage: 4 g per day.
• Treatment duration: 7 to 14 days.

Indication: Used for treating otitis media caused by susceptible strains of Streptococcus pneumoniae, Haemophilus influenzae, Staphylococcus aureus, Streptococcus pyogenes, and Moraxella catarrhalis.

Pharyngitis

• 250 to 333 mg taken orally every 6 hours, or 500 mg taken orally every 12 hours.
• Maximum dosage: 4 g per day.
• Treatment duration: 7 to 14 days.

Indication: Used for treating skin and soft tissue infections caused by susceptible gram-positive bacteria such as S. aureus and S. pyogenes.

Skin or Soft Tissue Infections

• 250 to 333 mg taken orally every 6 hours, or 500 mg taken orally every 12 hours.
• Maximum dosage: 4 g per day.
• Treatment duration: 7 to 14 days.

Osteomyelitis

• 250 to 333 mg taken orally every 6 hours, or 500 mg taken orally every 12 hours.
• Maximum dosage: 4 g per day.
• Treatment duration: 7 to 14 days.

Indication: Used for treating bone infections caused by susceptible S. aureus and Proteus mirabilis.

Cystitis

• 250 to 333 mg taken orally every 6 hours, or 500 mg taken orally every 12 hours.
• Maximum dosage: 4 g per day.
• Treatment duration: 7 to 14 days.

Indication: Used for treating genitourinary infections caused by susceptible Escherichia coli, P. mirabilis, and Klebsiella pneumoniae.

Prostatitis

• 250 to 333 mg taken orally every 6 hours, or 500 mg taken orally every 12 hours.
• Maximum dosage: 4 g per day.
• Treatment duration: 7 to 14 days.

Pyelonephritis

• 250 to 333 mg taken orally every 6 hours, or 500 mg taken orally every 12 hours.
• Maximum dosage: 4 g per day.
• Treatment duration: 7 to 14 days.

Upper Respiratory Tract Infections

• 250 to 333 mg taken orally every 6 hours, or 500 mg taken orally every 12 hours.
• Maximum dosage: 4 g per day.
• Treatment duration: 7 to 14 days.

Indication: Used for treating respiratory tract infections caused by susceptible S. pneumoniae and S. pyogenes.

Bacterial Infections

• 500 mg orally three to four times daily.

Uses:

• The preferred treatment for chronic suppression of oxacillin-susceptible staphylococcal infections.
• Alternative therapy for chronic suppression of beta-hemolytic streptococci or Propionibacterium species.

Bacterial Endocarditis Prophylaxis (AHA and IDSA Guidelines)

• 2 g orally as a single dose, administered 30 to 60 minutes before the procedure.

Indication: Used to prevent infective endocarditis in penicillin/ampicillin-allergic patients undergoing dental procedures (excluding those with immediate hypersensitivity).

IDSA Guidelines

• Skin or soft tissue infections: 500 mg orally four times daily.
• Impetigo: 250 mg orally four times daily.
• Pharyngitis: 20 mg/kg orally twice daily.
• Maximum single dose: 500 mg.
• Treatment duration: 10 days.

Uses:

• First-line treatment for nonpurulent cellulitis and diabetic foot infections caused by beta-hemolytic streptococci (e.g., methicillin-susceptible Staphylococcus aureus [MSSA], Streptococcus species).
• Alternative treatment for MSSA-induced skin and soft tissue infections in individuals allergic to penicillin (excluding immediate hypersensitivity).
• Treatment for impetigo caused by Staphylococcus and Streptococcus species.
• Management of Group A streptococcal pharyngitis in penicillin-allergic patients (except those with immediate hypersensitivity).
• Treatment of surgical site infections located on the trunk or extremities away from the perineal or axillary areas.

Dosage for Children

Cephalexin is commonly prescribed for children to treat bacterial infections, but the dosage must be carefully calculated based on the child’s weight. The medicine is preferred in pediatric patients due to improved taste and tolerability. Typically, the recommended pediatric dose ranges from 25 to 50 mg per kg per day, divided into multiple doses.

The dosage may be increased in severe infections, but it should not exceed the maximum daily limit of 4,000 mg. Liquid suspension is often used for younger children who cannot swallow pills. It is essential to shake the bottle well before use and measure the dose accurately using a medical syringe or dosing spoon. Parents should ensure their child completes the course of antibiotics to prevent bacterial resistance and reinfection. Now, let’s check the pediatric dosage for different conditions.

Otitis Media

• 12.5 to 25 mg/kg orally every 6 hours.

Pharyngitis

• Children over 1 year: 12.5 to 25 mg/kg orally every 12 hours.

Skin or Soft Tissue Infections

• 12.5 to 25 mg/kg orally every 12 hours.

Upper Respiratory Tract Infections

• Ages 1-15 years: 25 to 50 mg/kg orally per day, divided into equal doses.
• Severe infections: 50 to 100 mg/kg orally daily, divided into equal doses.
• Duration: 7 to 14 days.
• Ages 15 and older: Adult dosing guidelines apply.
• Beta-hemolytic streptococcal infections require at least 10 days of treatment.

Pediatric Infectious Diseases Society (PIDS) and IDSA Guidelines

• Over 3 months: Step-down therapy or mild infections: 75 to 100 mg/kg orally daily, divided into 3 to 4 doses.

Renal Dosage Adjustments (Ages 15 and older)

• CrCl 30 to 59 mL/min: Maximum daily dose limited to 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.

Precautions

Safety and efficacy in children under 1 year have not been established. For additional information, see the Precautions section, Side Effects and Contraindications for Age Groups.

What to Do in Case of a Missed Dose or Overdose

If a dose of Cephalexin is missed, it should be taken as soon as remembered. However, if it is almost time for the next dose, the missed dose should be skipped—never take a double dose to make up for a missed one. In the case of an overdose, symptoms may include nausea, vomiting, stomach pain, diarrhea, and seizures in severe cases. If an overdose is suspected, immediate medical attention should be sought, and poison control should be contacted.

Other Instructions

Cephalexin can be taken with or without food. Capsules and tablets should be swallowed with a full glass of water.

It is not recommended for treating severe systemic infections during the acute phase. Doctors may monitor blood clotting parameters (especially in patients at risk for prolonged prothrombin time) and kidney function for those with renal impairment.

Cephalexin is generally considered safe for use during pregnancy and breastfeeding. It belongs to FDA Pregnancy Category B, meaning no confirmed risks have been identified in human studies. However, it should only be used when needed and under medical supervision. In breastfeeding mothers, Cephalexin is excreted in small amounts in breast milk but is unlikely to cause harm to the infant. Some babies may experience mild diarrhea or gastrointestinal discomfort. Mothers should consult a healthcare provider if any unusual symptoms appear in the baby.

It is essential to report any unusual or severe side effects that may occur during treatment. Patients should remain vigilant for signs of a Clostridium difficile infection, such as bloody diarrhea, stomach cramps, or fever, which can develop even up to two months after completing the medication. To ensure effectiveness and prevent resistance, the full prescribed course should be completed, even if symptoms improve. Additionally, any remaining oral suspension should be properly discarded after the therapy is finished.

Even if symptoms improve within a few days, completing the entire prescribed course of Cephalexin is crucial to eliminate the infection fully. Stopping treatment early increases the risk of bacterial resistance, making future infections harder to treat. Additionally, incomplete treatment may lead to a relapse of the infection, requiring stronger antibiotics or longer treatment. Patients should strictly follow their doctor’s instructions and avoid skipping doses. For information on Cephalexin and Antibiotic Resistance, visit our detailed analysis.

Cephalexin is an effective antibiotic when taken correctly and at the right dosage. Pediatric patients require weight-based dosing, while special considerations must be made for pregnant and breastfeeding women. Completing the full course of treatment is essential to prevent bacterial resistance. Patients should follow the prescribed schedule carefully and know what to do in case of missed or excessive doses. If any concerns arise, consulting a healthcare provider is always the best approach.

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