Relapsing Fever Medication

Updated: Oct 13, 2021
  • Author: Geneva E Guarin, MD, MBA; Chief Editor: Michael Stuart Bronze, MD  more...
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Medication Summary

The goals of pharmacotherapy are to reduce morbidity and to prevent complications. In louse-borne relapsing fever (LBRF), single-dose therapy is recommended, as only one relapse typically occurs. Therapy for tickborne relapsing fever (TBRF) is extended to 7 to 10 days, as this form is characterized by multiple relapses.



Class Summary

Borrelia species that cause relapsing fever are sensitive to antibiotic agents.

Penicillin G procaine

Long-acting parenteral penicillin (IM only) to treat moderately severe infections caused by penicillin G-sensitive microorganisms.

In adults, administer by deep IM injection only into upper, outer quadrant of buttock. In infants and small children the midlateral aspect of the thigh may be a better site for administration.

Ceftriaxone (Rocephin)

Third-generation cephalosporin with broad-spectrum gram-negative activity; has lower efficacy against gram-positive organisms but higher efficacy against resistant organisms; highly stable in presence of beta-lactamases (penicillinase and cephalosporinase) of gram-negative and gram-positive bacteria; bactericidal activity results from inhibiting cell-wall synthesis by binding to 1 or more penicillin-binding proteins; exerts antimicrobial effect by interfering with synthesis of peptidoglycan (major structural component of bacterial cell wall); bacteria eventually lyse because activity of cell-wall autolytic enzymes continues while cell-wall assembly is arrested. Ceftriaxone may be used for CNS involvement in tickborne relapsing fever.

Penicillin G aqueous (Pfizerpen-G)

Interferes with synthesis of cell wall mucopeptide during active multiplication, resulting in bactericidal activity against susceptible microorganisms. May be used for CNS involvement in tickborne relapsing fever.


Acts by inhibiting bacterial protein synthesis. Binds reversibly to the 50S subunit of bacterial 70S ribosome and prevents attachment of the amino acid-containing end of the aminoacyl-tran to acceptor site on ribosome. Active in vitro against a wide variety of bacteria, including gram-positive, gram-negative, aerobic, and anaerobic organisms. Well-absorbed from GI tract and metabolized in the liver, where it is inactivated by conjugation with glucuronic acid and then excreted by the kidneys. Oral form is not available in the United States.

Doxycycline (Adoxa, Doryx, Monodox, Vibramycin, Morgidox)

Broad-spectrum, synthetically derived bacteriostatic antibiotic in the tetracycline class. Almost completely absorbed, concentrates in bile, and is excreted in urine and feces as a biologically active metabolite in high concentrations. Inhibits protein synthesis and, thus, bacterial growth by binding to 30S and possibly 50S ribosomal subunits of susceptible bacteria. May block dissociation of peptidyl t-RNA from ribosomes, causing RNA-dependent protein synthesis to arrest.


Treats gram-positive and gram-negative infections, as well as mycoplasmal, chlamydial, and rickettsial infections. Inhibits bacterial protein synthesis by binding with 30S and possibly 50S ribosomal subunit(s).

Erythromycin (Ery-Tab, E.E.S. 400, Erythrocin Stearate)

Inhibits bacterial growth, possibly by blocking dissociation of peptidyl t-RNA from ribosomes, causing RNA-dependent protein synthesis to arrest.