Contact dermatitis is a common cause of a rash in one area. This is especially true of a small rash that will not go away. Contact dermatitis usually starts as raised red spots. It can change to blisters, as in poison ivy. The rash is itchy. Contact dermatitis is an allergic skin rash. The location of the rash may suggest the cause:Disclaimer: This information is not intended to be a substitute for professional medical advice. It is provided for educational purposes only. You assume full responsibility for how you choose to use this information. Copyright 1994-2017 Schmitt Pediatric Guidelines LLC. All rights reserved. 8:00 am - 5:30 pm8:30 am - 11:30 am