Indication	Treatment	Duration, days (range)
Tick bite in the United States	Doxycycline, 200 mg in a single dosea,b; (4 mg/kg in children 8 years of age) and/or observation	...
Erythema migrans	Oral regimenc,d	14 (14–21)e
Early neurologic disease
Meningitis or radiculopathy	Parenteral regimenc,f	14 (10–28)
Cranial nerve palsya,g	Oral regimenc	14 (14–21)
Cardiac disease	Oral regimena,c,h or parenteral regimena,c,h	14 (14–21)
Borrelial lymphocytoma	Oral regimenc,d	14 (14–21)
Late disease
Arthritis without neurologic disease	Oral regimenc	28
Recurrent arthritis after oral regimen	Oral regimena,c or parenteral regimena,c	28 14 (14–28)
Antibiotic-refractory arthritisi	Symptomatic therapyj	...
Central or peripheral nervous system disease	Parenteral regimenc	14 (14–28)
Acrodermatitis chronica atrophicans	Oral regimenc	21 (14–28)
Post–Lyme disease syndrome	Consider and evaluate other potential causes of symptoms; if none is found, then administer symptomatic therapya	...

NOTE.     Regardless of the clinical manifestation of Lyme disease, complete response to treatment may be delayed beyond the treatment duration. Relapse may occur with any of these regimens; patients with objective signs of relapse may need a second course of treatment.
     ^a See text.
     ^b A single dose of doxycycline may be offered to adult patients and to children 8 years of age when all of the following circumstances exist: (1) the attached tick can be reliably identified as an adult or nymphal Ixodes scapularis tick that is estimated to have been attached for 36 h on the basis of the degree of engorgement of the tick with blood or of certainty about the time of exposure to the tick, (2) prophylaxis can be started within 72 h after the time that the tick was removed, (3) ecologic information indicates that the local rate of infection of these ticks with Borrelia burgdorferi is 20%, and (d) doxycycline is not contraindicated. For patients who do not fulfill these criteria, observation is recommended.
     ^c See table 2.
     ^d For adult patients intolerant of amoxicillin, doxycycline, and cefuroxime axetil, azithromycin (500 mg orally per day for 7–10 days), clarithromycin (500 mg orally twice per day for 14–21 days, if the patient is not pregnant), or erythromycin (500 mg orally 4 times per day for 14–21 days) may be given. The recommended dosages of these agents for children are as follows: azithromycin, 10 mg/kg per day (maximum of 500 mg per day); clarithromycin, 7.5 mg/kg twice per day (maximum of 500 mg per dose); and erythromycin, 12.5 mg/kg 4 times per day (maximum of 500 mg per dose). Patients treated with macrolides should be closely observed to ensure resolution of the clinical manifestations.
     ^e Ten days of therapy is effective if doxycycline is used; the efficacy of 10-day regimens with the other first-line agents is unknown.
     ^f For nonpregnant adult patients intolerant of -lactam agents, doxycycline (200–400 mg/day orally [or intravenously, if the patient is unable to take oral medications]) in 2 divided doses may be adequate. For children 8 years of age, the dosage of doxycycline for this indication is 4–8 mg/kg per day in 2 divided doses (maximum daily dosage of 200–400 mg).
     ^g See text. Patients without clinical evidence of meningitis may be treated with an oral regimen. Parenteral antibiotic therapy is recommended for patients with both clinical and laboratory evidence of coexistent meningitis. Most of the experience in the use of oral antibiotic therapy is for patients with seventh cranial nerve palsy. Whether oral therapy would be as effective for patients with other cranial neuropathies is unknown. The decision between oral and parenteral antimicrobial therapy for patients with other cranial neuropathies should be individualized.
     ^h A parenteral antibiotic regimen is recommended at the start of therapy for patients who have been hospitalized for cardiac monitoring; an oral regimen may be substituted to complete a course of therapy or to treat ambulatory patients. A temporary pacemaker may be required for patients with advanced heart block.
     ⁱ Antibiotic-refractory Lyme arthritis is operationally defined as persistent synovitis for at least 2 months after completion of a course of intravenous ceftriaxone (or after completion of two 4-week courses of an oral antibiotic regimen for patients who are unable to tolerate cephalosporins); in addition, PCR of synovial fluid specimens (and synovial tissue specimens, if available) is negative for B. burgdorferi nucleic acids.
     ^j Symptomatic therapy might consist of nonsteroidal anti-inflammatory agents, intra-articular injections of corticosteroids, or other medications; expert consultation with a rheumatologist is recommended. If persistent synovitis is associated with significant pain or if it limits function, arthroscopic synovectomy can reduce the period of joint inflammation.