Rashes are caused by a variety of tickborne diseases. Lyme disease typically starts with a round rash that looks like a bull’s eye. Usually, the rash is painless. The rash associated with STARI is also round, but the outer edge of the bull’s eye expands over time.
People with Rocky Mountain Spotted Fever may develop a flat, painless rash of red dots or patches on their arms and feet, but the rash can also appear in other places on the body. Rashes can develop within hours of the tick bite, but may not appear for up to 30 days after the initial bite.
Rash is also possible if you are allergic to ticks. Other signs of an allergic reaction after a tick bite include difficulty breathing, blisters at the site of the bite and pain or swelling after being bitten. Allergic reactions should be treated as a medical emergency, especially when swelling or other symptoms cause difficulty breathing. Additionally, some people develop allergies to ticks after being bitten previously with no reaction.