One symptom of Lyme disease is a red rash (called erythema migrans). The rash usually starts as a small red area and then expands over several days. The rash occurs at the site of the tick bite and usually gets bigger over time. Sometimes the rash clears in the center, so that it looks like a bull's-eye.

About half the people infected with Lyme disease develop the rash within 4 weeks. The rash usually isn't painful or itchy. It fades within 4 weeks, even without treatment for Lyme disease.