Does Keflex (Cephalexin) cover Lyme disease?

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Last updated: June 28, 2025View editorial policy

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From the Guidelines

Keflex (Cephalexin) is not effective for treating Lyme disease and should not be used. The most recent and highest quality study, published in 2006 in the Clinical Infectious Diseases journal 1, recommends doxycycline, amoxicillin, or cefuroxime axetil as the first-line treatments for early localized or early disseminated Lyme disease.

Key Points to Consider

  • Cephalexin, a first-generation cephalosporin, is inactive in vitro against B. burgdorferi and is ineffective clinically 1.
  • The preferred antibiotics for Lyme disease are:
    • Doxycycline (100 mg twice daily for 10-21 days)
    • Amoxicillin (500 mg three times daily for 14-21 days)
    • Cefuroxime axetil (500 mg twice daily for 14-21 days)

Importance of Proper Treatment

If you suspect Lyme disease, especially after a tick bite with symptoms like bull's-eye rash, fever, fatigue, or joint pain, it's crucial to seek medical attention promptly for proper diagnosis and treatment with an appropriate antibiotic regimen, as early treatment with the correct antibiotics is vital for preventing progression to more serious complications of Lyme disease 1.

From the Research

Keflex (Cephalexin) and Lyme Disease

  • Keflex, also known as Cephalexin, is a first-generation cephalosporin antibiotic 2.
  • It is not typically recommended for the treatment of Lyme disease due to its poor in vitro activity against Borrelia burgdorferi, the bacteria that causes Lyme disease 2.

Treatment of Lyme Disease

  • The recommended treatments for Lyme disease include oral antibiotics such as amoxicillin, doxycycline, and cefuroxime axetil 3, 4, 5.
  • For early Lyme disease, oral beta-lactam antibiotics and oral tetracyclines are considered effective first-line treatment modalities 4.
  • Ceftriaxone, a third-generation cephalosporin, has been shown to be effective in treating acute disseminated Lyme disease 6.

Efficacy of Keflex in Treating Lyme Disease

  • A study found that cephalexin was not effective in treating Lyme disease, with 11 patients experiencing disease progression despite treatment with cephalexin 2.
  • The study concluded that cephalexin should not be used to treat early Lyme disease and should be prescribed with caution during the summer months for patients believed to have cellulitis in locations where Lyme disease is endemic 2.

Conclusion Not Provided as per Request

  • Refer to the provided evidence for more information on the treatment of Lyme disease 3, 4, 5, 2, 6.

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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