Erythema migrans is the "bullseye" rash that shows up in 70% to 80% of people who are affected by Lyme disease. From the time of the bite, it can take three to 30 days for the rash to show up.
Typically, the rash starts out small and spreads up to 12 inches in diameter or more. The center may clear, or the rash can take on a bullseye appearance. Because the rash looks different depending on the person and the stage of the disease, it's a good idea to have your primary care provider look at any suspicious rash. If you live in an area where ticks abound and/or Lyme disease is common, it's even more important to be on your toes and be aware of any unusual rashes.
This is one way the rash can appear. This presentation has the typical outside ring and center clearing that is dark purple.
