For early localized Lyme disease, what is first-line therapy in nonpregnant patients?

• A. Amoxicillin 500 mg three times daily for 14-21 days
• B. Doxycycline 100 mg twice daily for 10–21 days
• C. Cefuroxime axetil 500 mg twice daily for 14 days
• D. Azithromycin 500 mg daily for 10 days

Answer: (B)

Doxycycline is the preferred first-line treatment for early localized Lyme disease in nonpregnant adults. It provides reliable activity against Borrelia burgdorferi, is easily given orally, and has good tolerability. The typical course is 10–21 days, with 100 mg taken twice daily; many patients complete therapy in about 14 days, though up to 21 days is acceptable depending on symptoms. Amoxicillin is favored during pregnancy or in young children due to safety concerns with doxycycline. Cefuroxime axetil is a reasonable alternative if doxycycline cannot be used, but it is not as convenient. Azithromycin is not recommended because it has inferior efficacy and higher relapse rates.