Dreams dictionary: Rash
Dreams dictionary: Interpretation 1
To dream that you have a rash indicates repressed anger, frustrations and annoyances. You may be holding in your anger and frustrations, instead of expressing it. Alternatively, the dream suggests that others are trying to put doubt in your head about some decision or choice that you are making. It may be a pun on a "rash" decision that you are making. You need to think twice before going through with your choice.