Also, it is possible that the skin lesion does not take the form of a rash but it may include papules, blisters, vesicles or even a simple red area. The main difference between the rash caused by allergic contact dermatitis and the one caused by irritant contact dermatitis is that the latter tends to be confined to the area where the trigger touched the skin, whereas in allergic contact dermatitis the rash is more likely to be more widespread on the skin.[3] Another characteristic of the allergic contact dermatitis rash is that it usually appears after a day or two after exposure to the allergen, unlike irritant contact dermatitis that appears immediately after the contact with the trigger.