Many of the rashes we've looked at are isolated occurrences. But what about a rash that you've seen before -- and it's coming back? You could have a recurring rash.
Eczema includes a broad number of itchy, red rashes, the cause of which is unknown. The most severe of these is atopic dermatitis, a rash that often appears on the inside of the elbows, back of the knees or face [source: National Eczema Association].
Atopic dermatitis is not contagious. Researchers believe the condition is genetic, passed down from one or both parents [source: National Eczema Association].