Antimicrobial therapy for relapsing fever in adults depends on the vector (Tick-borne vs. Louse-borne) and includes either Doxycycline, Erythromycin, or Tetracyclines. Intravenous Ceftriaxone is added if either meningitis or encephalitis is present.

• Erythromycin, Tetracyclines, Chloramphenicol, or Penicillins have all been shown to be effective for treating tick-borne relapsing fever TBRF. Although the duration of therapy has not been well studied for TBRF, the current recommendation is seven days of antibiotic therapy. In contrast, louse-borne relapsing fever caused by B. recurrentis can be treated with a single dose of antibiotics.
• For young children and pregnant women either Erythromycin and/or Penicillin are recommended for the treatment of TBRF.

• Preferred regimen: Doxycycline 100 mg PO bid for 5-10 days^[1]
• Alternative regimen: Erythromycin 500 mg PO qid for 5-10 days
• Note: If meningitis/encephalitis present, use Ceftriaxone 2 g IV q12h for 14 days

• Preferred regimen: Tetracycline 500 mg PO single dose
• Alternative regimen: Erythromycin 500 mg PO single dose

When initiating antibiotic therapy, a patient should be watched closely for a Jarisch-Herxheimer reaction for the first 4 hours after the antibiotic is given. The reaction may be difficult to distinguish from a febrile crisis, with rigors and decreased blood pressure. Cooling blankets and appropriate use of antipyretic agents may be indicated and may be lessened by giving acetaminophen 650 mg orally 2 hours before and 2 hours after the first dose of antibiotic therapy. This reaction tends to be more severe in patients with louse-borne relapsing fever treated with penicillin.