From the Guidelines
Cephalexin is not the preferred treatment for sinus infections due to its poor coverage of common bacterial pathogens, such as Haemophilus influenzae and Moraxella catarrhalis. According to the guidelines published in the Journal of Allergy and Clinical Immunology 1, first-generation cephalosporins like cephalexin have limited activity against these bacteria, making them less effective for treating acute bacterial sinusitis.
Key Points to Consider
- The most common bacteria causing sinus infections are Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis 1.
- Cephalexin has poor coverage against Haemophilus influenzae and Moraxella catarrhalis, which are commonly involved in sinus infections 1.
- Amoxicillin (with or without clavulanate) is generally preferred as the first-line treatment for sinus infections due to its broader spectrum of activity against the common bacterial pathogens involved 1.
- Cephalexin might be considered as an alternative treatment option in patients with a penicillin allergy or in cases where the infection has not responded to first-line treatments.
Treatment Recommendations
- For acute bacterial sinusitis, the typical adult dose of amoxicillin-clavulanate is 500-875 mg taken orally every 12 hours, or 250-500 mg every 8 hours, for 5-10 days depending on infection severity 1.
- It is essential to complete the full course of antibiotics, even if symptoms improve before finishing, to ensure effective treatment and prevent the development of antibiotic resistance.
- A healthcare provider should determine if the sinus infection is bacterial before prescribing any antibiotic, as viral sinus infections are more common and do not require antibiotic treatment 1.
From the FDA Drug Label
Cephalexin is indicated for the treatment of the following infections when caused by susceptible strains of the designated microorganisms: Respiratory tract infections caused by Streptococcus pneumoniae and Streptococcus pyogenes Note—Culture and susceptibility tests should be initiated prior to and during therapy.
Cephalexin can be used to treat respiratory tract infections, which may include sinus infections, but only if caused by susceptible strains of the designated microorganisms, such as Streptococcus pneumoniae. However, the label does not explicitly state that cephalexin is indicated for the treatment of sinus infections.
- The drug label does mention respiratory tract infections, but it does not provide specific information about sinus infections. 2
From the Research
Cephalexin and Sinus Infections
- Cephalexin is effective in treating sinusitis, with satisfactory clinical results obtained in 83% of patients 3.
- The majority of patients received cephalexin, 1 gm/day in four divided doses for ten days, including the 48-hour period after the patient had become asymptomatic 3.
- Bacteriology results showed that many of the pathogens usually involved in infectious maxillary sinusitis were resistant to the recommended or frequently prescribed antibiotics, but not to cephalexin 3.
Comparison with Other Antibiotics
- Cefdinir, given once or twice daily, was as effective clinically as amoxicillin-clavulanate given three times daily in the treatment of acute community-acquired bacterial sinusitis (ACABS) 4.
- Microbiologic eradication rates were also similar in the three groups 4.
- Cefuroxime axetil twice a day was as effective as amoxicillin/clavulanate three times a day in the treatment of acute bacterial maxillary sinusitis, but produced fewer adverse effects 5.
Limitations and Side Effects
- Cephalexin may not be effective in treating sinus infections caused by Haemophilus influenzae 6.
- Adverse effects of cephalexin, such as gastrointestinal upsets, rash, and urticaria, have been relatively infrequent and have not required discontinuance of the drug 6.
- Amoxicillin-clavulanate was associated with a significantly higher incidence of drug-related adverse events, particularly diarrhea 5.