How should i treat a mild chemical burn or allergic skin reaction?

Wash and steroids: Thoroughly wash the skin from the irritant chemical and apply a topical steroid, but if the skin peels or darkens in color, seek medical help, it may be worse than you thought.

They are different: A mild burn like a red area or blister can be treated with cool moist dressings. Allergic skin reaction need to be evaluated by a medical professional. If very mild a Hydrocortisone cream may help. If it itches an antihistamine may help. Best to have it looked at.