Cephalexin, also known by the brand name Keflex, is a first-generation cephalosporin antibiotic used to treat various bacterial infections. It is a bactericidal medication, meaning it works by killing bacteria. Cephalexin's broad spectrum of activity makes it effective against many common bacterial pathogens.
What is Cephalexin and How Does it Work?
Cephalexin functions by interfering with bacterial cell wall synthesis. It inhibits the production of peptidoglycan, a vital component of bacterial cell walls, leading to weakened cell walls and bacterial death. This action makes it effective against susceptible gram-positive and some gram-negative bacteria. Cephalexin should only be used for bacterial infections, as its misuse against viruses contributes to antibiotic resistance.
Key Infections Cephalexin Treats
Cephalexin is prescribed for a variety of bacterial infections.
Skin and Soft Tissue Infections
It is effective against common bacterial skin and soft tissue infections caused by susceptible Staphylococcus aureus and Streptococcus pyogenes. These include cellulitis, impetigo, abscesses, and boils.
Urinary Tract Infections (UTIs)
Cephalexin is used for mild to moderate UTIs caused by susceptible bacteria such as Escherichia coli, Klebsiella pneumoniae, and Proteus mirabilis. While effective, it may not be a first-line treatment in some cases to help prevent resistance.
Respiratory Tract Infections
Cephalexin can be used for certain respiratory tract infections. It is an alternative treatment for strep throat in patients with a mild penicillin allergy. It can also be used for some mild to moderate bacterial pneumonia cases.
Middle Ear Infections (Otitis Media)
Cephalexin is approved by the FDA for treating otitis media caused by susceptible organisms, including Streptococcus pneumoniae and Moraxella catarrhalis.
Bone and Joint Infections
Specific bone and joint infections caused by susceptible staphylococci or Proteus mirabilis may be treated with cephalexin.
Dental Infections
Cephalexin can be used to treat bacterial dental infections, such as abscesses.
Cephalexin vs. Other Common Antibiotics
| Feature | Cephalexin (Keflex) | Amoxicillin (Amoxil) | Penicillin V Potassium | Augmentin (amoxicillin/clavulanate) |
|---|---|---|---|---|
| Drug Class | First-generation cephalosporin | Penicillin | Penicillin | Combination penicillin/beta-lactamase inhibitor |
| Common Uses | Skin infections, UTIs, ear infections, strep throat (allergy) | Broader range than penicillin, ear infections, strep throat, pneumonia | Strep throat, skin infections, rheumatic fever prevention | Ear infections, skin infections, pneumonia, and other infections resistant to amoxicillin alone |
| Key Differences | Effective alternative for mild penicillin allergy. | Often first-line for strep throat; similar action to penicillin. | Narrower spectrum; gold standard for strep throat due to low resistance. | Contains a beta-lactamase inhibitor to overcome resistance; broader coverage. |
Administration and Important Considerations
Cephalexin is available in various oral forms.
- Complete the full course: Always finish the entire prescription to prevent recurrence and resistance.
- Administration: It can usually be taken with or without food.
- Renal Function: Dosage adjustments are needed for patients with kidney problems, and these should be determined by a healthcare professional.
Common Side Effects
Common side effects include nausea, vomiting, diarrhea, and stomach pain. Serious side effects, though rare, can include severe allergic reactions, Clostridium difficile-associated diarrhea (CDAD), seizures, and severe skin reactions.
Conclusion
Cephalexin is a valuable antibiotic for treating a variety of bacterial infections, including those affecting the skin, urinary tract, respiratory system, and ears. It is also an important alternative for individuals with penicillin allergies. Adhering to prescribed instructions and completing the full course of treatment are essential for effective outcomes and to combat antibiotic resistance. Always consult a healthcare professional for appropriate diagnosis and treatment.
