Cephalexin: Effective Bacterial Infection Treatment
Cephalexin
| Product dosage: 250mg | |||
|---|---|---|---|
| Package (num) | Per pill | Price | Buy |
| 30 | $1.40 | $42.00 (0%) | 🛒 Add to cart |
| 60 | $1.08 | $84.00 $65.00 (23%) | 🛒 Add to cart |
| 90 | $0.97 | $126.00 $87.00 (31%) | 🛒 Add to cart |
| 120 | $0.92 | $168.00 $110.00 (35%) | 🛒 Add to cart |
| 180 | $0.85 | $252.00 $153.00 (39%) | 🛒 Add to cart |
| 270 | $0.82 | $378.00 $222.00 (41%) | 🛒 Add to cart |
| 360 | $0.80
Best per pill | $504.00 $289.00 (43%) | 🛒 Add to cart |
Cephalexin is a first-generation cephalosporin antibiotic prescribed to combat a wide range of bacterial infections. It operates by interfering with the bacteria’s cell wall synthesis, leading to bacterial cell death. This medication is a cornerstone in outpatient treatment due to its reliable efficacy against common pathogens and favorable safety profile. Proper diagnosis and adherence to the prescribed regimen are crucial for optimal therapeutic outcomes and mitigating antibiotic resistance.
Features
- Active Ingredient: Cephalexin (as monohydrate)
- Drug Class: First-generation cephalosporin antibiotic
- Available Forms: Oral capsules (250 mg, 500 mg), tablets (250 mg, 500 mg), and oral suspension (125 mg/5 mL, 250 mg/5 mL)
- Mechanism of Action: Inhibits bacterial cell wall synthesis by binding to penicillin-binding proteins (PBPs)
- Spectrum of Activity: Effective against many Gram-positive bacteria and some Gram-negative bacteria
- Bioavailability: Well-absorbed from the gastrointestinal tract, with peak serum concentrations occurring within 1 hour
- Half-life: Approximately 0.5–1.2 hours in adults with normal renal function
- Excretion: Primarily renal, requiring dosage adjustment in renal impairment
Benefits
- Rapid onset of action, with symptomatic improvement often observed within 24–48 hours of initiation
- Broad-spectrum coverage against common outpatient pathogens, including streptococci and staphylococci (including penicillinase-producing strains)
- High oral bioavailability, allowing for effective treatment without the need for intravenous administration in many cases
- Generally well-tolerated, with a low incidence of severe adverse effects when used as directed
- Proven efficacy in both adult and pediatric populations, with appropriate weight-based dosing
- Cost-effective therapeutic option due to widespread availability in generic formulations
Common use
Cephalexin is indicated for the treatment of bacterial infections caused by susceptible strains of microorganisms. Common clinical applications include:
- Respiratory tract infections, such as pharyngitis, tonsillitis, and acute bronchitis caused by Streptococcus pyogenes (Group A streptococcus)
- Skin and soft tissue infections, including cellulitis, impetigo, and wound infections, frequently caused by Staphylococcus aureus (including penicillinase-producing strains) and/or streptococci
- Bone and joint infections, particularly osteomyelitis caused by susceptible staphylococci
- Genitourinary tract infections, including acute and uncomplicated cystitis caused by Escherichia coli, Proteus mirabilis, and Klebsiella pneumoniae
- Otitis media caused by Streptococcus pneumoniae, Haemophilus influenzae, staphylococci, and streptococci
- Dental infections and prophylaxis in certain dental procedures for patients with specific cardiac conditions
It is crucial to note that cephalexin is ineffective against viral infections, methicillin-resistant Staphylococcus aureus (MRSA), and most anaerobic bacteria. Culture and susceptibility testing should be performed to guide therapy when appropriate.
Dosage and direction
Dosage must be individualized based on the infection’s severity, causative organism, and patient’s renal function. The usual adult dosage is 250 mg every 6 hours, though more severe infections may require 500 mg every 6–12 hours. For streptococcal pharyngitis, skin and soft tissue infections, and uncomplicated cystitis, dosing may be 500 mg every 12 hours.
Pediatric dosing is typically 25–50 mg/kg/day in divided doses every 6–12 hours, not to exceed adult dosing. For otitis media, the recommended dose is 75–100 mg/kg/day in four divided doses.
Administration should occur at evenly spaced intervals to maintain constant serum levels. The oral suspension should be shaken well before each use. Cephalexin may be taken with or without food; however, administration with food may minimize potential gastrointestinal upset.
For patients with renal impairment, dosage adjustment is necessary:
- Creatinine clearance 10–50 mL/min: Administer 50–100% of standard dose every 8–12 hours
- Creatinine clearance <10 mL/min: Administer 50% of standard dose every 12–24 hours
- Patients undergoing hemodialysis: Administer 250–500 mg after each dialysis session
The typical treatment duration is 7–14 days, though this may vary based on infection type and clinical response. Complete the full prescribed course even if symptoms improve earlier to prevent recurrence and development of resistance.
Precautions
Before initiating cephalexin therapy, clinicians should:
- Obtain a thorough allergy history, particularly regarding penicillin and cephalosporin hypersensitivity. Cross-reactivity between penicillins and cephalosporins occurs in approximately 5–10% of patients with penicillin allergy
- Assess renal function through serum creatinine measurement, especially in elderly patients or those with pre-existing renal impairment
- Exercise caution in patients with history of gastrointestinal disease, particularly colitis, as antibiotic use may precipitate pseudomembranous colitis
- Monitor for superinfection or fungal overgrowth during prolonged therapy
- Use with caution in patients with history of seizure disorders, as high doses may lower seizure threshold
- Consider potential alteration of laboratory tests: false-positive urinary glucose tests with Benedict’s solution, Fehling’s solution, or Clinitest tablets may occur (though not with glucose oxidase tests)
- Be aware that prolonged use may result in overgrowth of nonsusceptible organisms
Patients should be advised to report any signs of allergic reaction, severe diarrhea, or unusual bleeding/bruising promptly. Those taking oral contraceptives should use alternative contraception methods during therapy, as antibiotics may reduce contraceptive efficacy.
Contraindications
Cephalexin is contraindicated in patients with:
- Known hypersensitivity to cephalexin or any component of the formulation
- History of severe immediate hypersensitivity reactions (anaphylaxis) to any cephalosporin antibiotic
- Previous history of cephalexin-associated hepatitis or cholestatic jaundice
Relative contraindications include:
- History of non-severe penicillin allergy (requires careful risk-benefit assessment)
- Severe renal impairment without appropriate dosage adjustment
- History of antibiotic-associated colitis
Possible side effect
The most commonly reported adverse effects (occurring in >1% of patients) include:
- Gastrointestinal: Diarrhea (up to 10%), nausea, vomiting, dyspepsia, abdominal pain
- Dermatological: Rash, urticaria, pruritus
- Genitourinary: Genital pruritus, vaginitis, vaginal discharge
Less common but potentially serious adverse effects (<1% incidence) include:
- Hypersensitivity reactions: Angioedema, anaphylaxis, serum sickness-like reactions
- Hematological: Eosinophilia, neutropenia, thrombocytopenia, hemolytic anemia
- Hepatic: Transaminase elevation, cholestatic jaundice, hepatitis
- Renal: Interstitial nephritis, elevated BUN and creatinine
- Central nervous system: Dizziness, fatigue, headache, confusion (especially in renal impairment)
- Gastrointestinal: Pseudomembranous colitis caused by Clostridium difficile (symptoms may occur during or after treatment)
Patients should be instructed to seek immediate medical attention for severe diarrhea, bloody stools, skin blistering, difficulty breathing, or swelling of the face/throat.
Drug interaction
Cephalexin may interact with several medications:
- Probenecid: Concurrent administration may decrease renal tubular secretion of cephalexin, resulting in increased and prolonged blood levels
- Oral anticoagulants (warfarin): May potentiate anticoagulant effect through mechanism not fully elucidated; monitor INR closely
- Metformin: Cephalexin may increase metformin concentrations, potentially increasing risk of lactic acidosis
- Live bacterial vaccines (typhoid vaccine): Antibiotics may diminish therapeutic effect; avoid concurrent administration
- Nephrotoxic agents (aminoglycosides, loop diuretics): May increase risk of nephrotoxicity; monitor renal function
- Urine glucose tests: May cause false-positive results with copper reduction tests
Always inform healthcare providers of all medications, including over-the-counter drugs and supplements, before starting cephalexin therapy.
Missed dose
If a dose is missed, take it as soon as remembered unless it is almost time for the next scheduled dose. In that case, skip the missed dose and resume the regular dosing schedule. Do not double the dose to make up for a missed one. Maintaining consistent antibiotic levels is important for efficacy, so patients should try to adhere strictly to the prescribed dosing interval.
Overdose
Cephalexin overdose may manifest as nausea, vomiting, epigastric distress, diarrhea, and hematuria. In cases of significant overdose, particularly in patients with renal impairment, neurotoxicity including seizures may occur.
Management is primarily supportive:
- Gastric lavage or activated charcoal may be considered if ingestion was recent
- Maintain hydration and electrolyte balance
- Monitor renal function and neurological status
- Hemodialysis may enhance elimination in cases of significant overdose with renal impairment
There is no specific antidote. Contact a poison control center or seek immediate medical attention for overdose management.
Storage
Store at controlled room temperature (20–25°C or 68–77°F), in a tight, light-resistant container. Keep the oral suspension refrigerated (2–8°C or 36–46°F) and discard any unused portion after 14 days. Do not freeze. Keep all medications out of reach of children and pets. Do not use beyond the expiration date printed on the packaging.
Disclaimer
This information is for educational purposes only and does not constitute medical advice. Always consult with a qualified healthcare professional for diagnosis and treatment of medical conditions. The prescribing physician should determine the appropriate therapy based on individual patient factors. Do not initiate, discontinue, or change dosage of any medication without professional medical supervision.
Reviews
Clinical studies demonstrate cephalexin’s efficacy:
- A meta-analysis of 15 studies showed clinical cure rates of 85-95% for uncomplicated skin and soft tissue infections
- In respiratory tract infections, cephalexin demonstrates comparable efficacy to penicillin for streptococcal pharyngitis with cure rates exceeding 90%
- For uncomplicated urinary tract infections, clinical studies report bacteriological cure rates of 85-90% when caused by susceptible organisms
Patient-reported outcomes: Most patients report significant symptom improvement within 2-3 days of initiation when taken as prescribed. Common feedback includes convenience of dosing schedule and generally good tolerability. Some patients report gastrointestinal discomfort, which often resolves with continued use or administration with food.
Professional medical organizations continue to include cephalexin in treatment guidelines for appropriate indications, acknowledging its role as a well-established therapeutic option with decades of clinical experience supporting its use.