A rash is a specific manifestation of a skin disease on the skin and, depending on the rash and the disease, it can take different amounts of time to disappear, from a few hours quickly to a few days or even months slowly. Some rashes can be long-lasting. Rashes can generally be divided into those caused by acute illnesses, such as erythema and wind-bursts caused by urticaria, which can disappear within a few hours to 24 hours and are treated mainly with anti-allergy therapy. Rashes such as blisters caused by viral infections can generally subside and heal in about a week after antiviral treatment. Rashes caused by certain chronic diseases, such as chronic eczema and psoriasis, which cause erythema and papules, take longer to subside and may even persist for a long time. During the existence of the rash, try not to scratch the irritation, avoid contact with irritating substances, such as laundry detergent, detergent, etc.. Avoid spicy and stimulating foods as well as high-protein foods, such as fish and shrimp.