Ehrlichiosis Medication

Updated: Jun 22, 2021
  • Author: Chinelo N Animalu, MD, MPH, FIDSA; Chief Editor: Michael Stuart Bronze, MD  more...
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Medication Summary

The drug of choice for infections with human monocytic ehrlichiosis (HME) and human granulocytic anaplasmosis (HGA) in both adults and children is doxycycline. It is also the recommended drug for many other tick-borne infections, such as Rocky Mountain spotted fever. 

Early initiation of doxycycline should be done once there is a high index of suspicion of either human monocytic ehrlichiosis (HME) or human granulocytic anaplasmosis (HGA as delay in treatment is usually associated with increased morbidity especially in immunocompromised hosts. Supportive management such as antipyretics, hydration with intravenous fluids, should also be initiated if indicated.

The American Academy of Pediatrics recommends a short course of doxycycline (< 21 days) as first-line therapy for severe/life threatening suspected or proven HGA and HME in children of all ages. Tetracyclines in general are known to cause teeth discoloration in young children, however, this risk is minimal if a short course of doxycycline is used. [17]

Doxycycline can be administered intravenously in patients who are very sick and are unable to tolerate oral medications or given orally in less sick patients who can tolerate pills. Dose is usually 100mg every 12 hours for a duration of 7 to 10 days or continued for 3 to 5 days after resolution of fever in adults or for 7 to 14 days in children. Treatment should be continued for at least 3 days after resolution of fever. [18, 19]

For patients who are intolerant or have severe allergy to doxycycline, rifampin and chloramphenicol are alternative treatment options.

Rifampin has been used as an alternative agent in both adults and children and even in pregnant women. Children treated with rifampin will need closer monitoring. [18]

There is limited data about the use of Chloramphenicol in this setting although it has been used in a few instances but given its hematological adverse effects, it is usually avoided. Oral chloramphenicol is not readily available in most pharmacies in the United States. 


Currently, there is no recommendation for the use of doxycycline or other antibiotics for post tick exposure prophylaxis against HME or HGA. Individuals with potential tick-bite exposure should monitor for development of symptoms such as feeling unwell, fever, new rash within 2 weeks of exposure and contact their healthcare providers for further evaluation.




Class Summary

Empiric antimicrobial therapy should cover the most likely pathogens in the context of the clinical setting.

Doxycycline (Vibramycin, Doryx, Adoxa)

This is a second-generation tetracycline. It is more active than tetracycline against many pathogens. Doxycycline has different pharmacokinetics and a different adverse effect profile from tetracycline.

Doxycycline inhibits protein synthesis and thus bacterial growth by binding with 30S and, possibly, 50S ribosomal subunits of susceptible bacteria.

Rifampin (Rifadin)

Rifampin inhibits ribonucleic acid (RNA) synthesis in bacteria by binding to the beta subunit of deoxyribonucleic acid (DNA)-dependent RNA polymerase, which, in turn, blocks RNA transcription.