Keflex (cephalexin) is a first-generation cephalosporin antibiotic prescribed for the treatment of a wide range of bacterial infections. It operates by interfering with the synthesis of the bacterial cell wall, leading to bacterial cell death. This medication is effective against numerous gram-positive and some gram-negative organisms, making it a versatile choice for clinicians. Proper diagnosis and adherence to prescribed dosing are critical for therapeutic success and minimizing resistance development.

Features

• Active ingredient: Cephalexin
• Drug class: First-generation cephalosporin antibiotic
• Available forms: 250 mg, 500 mg, and 750 mg capsules; 125 mg/5 mL and 250 mg/5 mL oral suspensions
• Mechanism: Bactericidal; inhibits bacterial cell wall synthesis
• Spectrum: Effective against susceptible strains of Staphylococcus aureus, Streptococcus pneumoniae, Escherichia coli, and others

Benefits

• Rapid onset of action with bactericidal effects
• High bioavailability and effective tissue penetration
• Well-established safety profile with extensive clinical use
• Convenient oral administration suitable for outpatient treatment
• Effective for both uncomplicated and moderate infections
• Lower risk of Clostridioides difficile infection compared to broader-spectrum antibiotics

Common use

Keflex is commonly prescribed for bacterial infections including skin and soft tissue infections (e.g., cellulitis, impetigo), respiratory tract infections (such as pharyngitis and bronchitis caused by susceptible organisms), otitis media, bone infections, and genitourinary tract infections including uncomplicated cystitis. It is also used for surgical prophylaxis in certain procedures. Diagnosis should be confirmed via culture and susceptibility testing where appropriate to ensure targeted therapy.

Dosage and direction

Dosage varies based on infection severity, patient age, renal function, and pathogen susceptibility. For adults, typical doses range from 250 mg to 1 g every 6 to 12 hours. Pediatric dosing is usually 25 to 100 mg/kg/day divided into 2 to 4 doses. Take with food or milk to minimize gastrointestinal upset. Complete the full course of therapy even if symptoms improve earlier to prevent recurrence and resistance. Dosage adjustment is necessary in patients with renal impairment (creatinine clearance <50 mL/min).

Precautions

Inform your healthcare provider of any history of kidney disease, gastrointestinal conditions (especially colitis), or allergies. Use with caution in patients with a history of penicillin allergy due to potential cross-reactivity (estimated 1-10%). Prolonged use may result in fungal or bacterial superinfection. Monitor renal function periodically during extended therapy. Not recommended during pregnancy unless clearly needed (Category B). Cephalexin is excreted in breast milk; consider benefits versus risks when nursing.

Contraindications

Keflex is contraindicated in patients with known hypersensitivity to cephalexin or any cephalosporin antibiotic. Do not use in cases of previous anaphylactic reaction to penicillins or other beta-lactam antibiotics. Avoid in patients with a history of severe gastrointestinal disease, including antibiotic-associated colitis.

Possible side effect

Common side effects include diarrhea, nausea, vomiting, abdominal pain, and dyspepsia. Less frequently, dizziness, fatigue, headache, and genital pruritus may occur. Serious but rare adverse effects include pseudomembranous colitis, Stevens-Johnson syndrome, allergic reactions (rash, urticaria, anaphylaxis), interstitial nephritis, and hematologic changes (e.g., neutropenia, thrombocytopenia). Discontinue and seek medical attention if severe reactions occur.

Drug interaction

Probenecid may reduce renal excretion of cephalexin, increasing serum levels. Concurrent use with potent diuretics (e.g., furosemide) may enhance nephrotoxicity. Oral anticoagulants (e.g., warfarin) may have enhanced effects; monitor INR closely. Concomitant use with bacteriostatic antibiotics may reduce cephalexin’s efficacy. Avoid with live bacterial vaccines due to potential decreased immune response.

Missed dose

If a dose is missed, take it as soon as remembered unless it is almost time for the next dose. Do not double the dose to catch up. Maintaining consistent antibiotic levels is crucial for efficacy; irregular dosing may promote resistance.

Overdose

Symptoms of overdose may include nausea, vomiting, epigastric distress, diarrhea, and hematuria. Management is supportive; gastric lavage may be considered if ingestion was recent. Hemodialysis can remove cephalexin from the bloodstream. Contact a poison control center or seek emergency medical attention immediately.

Storage

Store at room temperature (20-25°C or 68-77°F) in a tightly closed container, protected from light and moisture. Keep suspension form refrigerated and discard any unused portion after 14 days. Keep out of reach of children and pets. Do not use beyond the expiration date.

Disclaimer

This information is for educational purposes and does not replace professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider for personalized recommendations. Do not initiate, adjust, or discontinue medication without medical supervision.

Reviews

Keflex has been widely used since the 1970s and is generally well-regarded for its efficacy in treating common bacterial infections. Clinical studies and post-marketing surveillance confirm its effectiveness for indicated uses when prescribed appropriately. Patient reviews often note rapid symptom improvement, though gastrointestinal side effects are commonly reported. Healthcare professionals value its reliability and favorable pharmacokinetic profile for outpatient management.