Hello, if you spot a tick and you develop a bulls eye rash but no other symptoms of lyme, how long is the initial treatment period of antibitics?

7-14days: If you develop rash, fevers, or other symptoms, 7-14 days of Doxycycline is the recommended treatment . http://www.cdc.gov/mmwr/preview/mmwrhtml/rr5504a1.htm.

Treatment Varies: The disease you are referring to is lyme disease which classically presents with a bulls eye rash. Generally, for lyme disease without other symptoms antibiotics are taken for 14 days. Symptomatic treatment lasts from 21-28 days. Each case is different so speak with your doctor.

14to21 days: With history of tick bite and bulls eye rash called erythema migrance, treatment with antibiotics like doxycycline, or amoxicillin, or cedtrixone is for 14to21 days according to cdc guidelines.