A person who identifies an attached tick may inquire about antibiotic prophylaxis to prevent Lyme's disease.


Recommended antibiotic for prophylaxis: doxycycline


Dosage regimen:

(1) for adult: 200 mg po in a single dose

(2) for an older child or adolescent: 4 mg per kg body weight (up to 200 mg) in a single dose


Criteria for administering prophylactic doxycycline - ALL of the following:

(1) The tick is identified as an adult or nymphal stage of Ixodes scapularis (based on examination after removal).

(2) The tick was attached for > 36 hours (based on the level of engorgement or possible time of exposure).

(3) Therapy can be started within 72 hours after tick removal.

(4) The infection rate in ticks from the locale is > 20%.

(5) No contraindications for the use of doxycycline (NOT < 8 years old, NOT pregnant female, NOT lactating female)


If the patient does not meet all of the criteria for prophylaxis, then the patient should be observed for early signs of infection (such as erythema migrans), without antibiotic prophylaxis.


To read more or access our algorithms and calculators, please log in or register.