Overview

Most tick bites are painless and cause only minor signs and symptoms, such as a change in skin color, swelling or a sore on the skin.

But some ticks spread bacteria that cause illnesses, including Lyme disease and Rocky Mountain spotted fever. In general, to spread Lyme disease a tick needs to be attached to a person's skin for at least 36 hours. Other infections can be transferred in a few hours or even a few minutes.