The mainstay of therapy in ehrlichiosis is antimicrobial therapy. Doxycycline is the drug of choice to treat ehrlichiosis.

Doxycycline is the first line treatment for adults and children of all ages and should be initiated immediately whenever ehrlichiosis is suspected.

• 1. Human Monocytic Ehrlichiosis or Human Granulocytic Anaplasmosis (adult) ^{[1] [2]}

• Preferred regimen: Doxycycline 100 mg PO/IV q12h for 7-14 days
• Note: Patients should be treated for at least 3 days after the fever subsides and until there is evidence of clinical improvement
• Alternative regimen (1): Chloramphenicol 500mg PO qid
• Alternative regimen (2): Rifampin 600 mg PO/IV qd for 7-10 days

• 2. Human Monocytic Ehrlichiosis or Human Granulocytic Anaplasmosis (pediatric)

• 2.1 ≥ 8 years old

• Preferred regimen: Doxycycline 2 mg/kg IV/PO q12h (Maximum, 200 mg/day) for 10 days

• 2.2 < 8 years old without Lyme disease

• Preferred regimen: Doxycycline 2 mg/kg IV/PO q12h (Maximum, 200 mg/day) for 4-5 days (or 3 days after resolution of fever)

• 2.3 co-infected with Lyme disease

• Preferred regimen: Doxycycline, then Amoxicillin 50 mg/kg in 3 divided doses (Maximum, 500 mg/dose) OR Cefuroxime 30 mg/kg in 2 divided doses (Maximum, 500 mg/dose) for 14 days