My 2 y/o son gets a red, not swollen, blotchy edged patch on one leg. I would blame it on heat but it is only one leg (mostly outside bottom half of leg and slight on thigh). I would blame allergies but we can t nail down anything that he comes in contact with only on that part of the leg or any environment that causes it. It does seem to happen when the weather gets hot (we live in Florida so that is often). It does seem to be radiating some heat of its own.