A patch of bumps on your body when you scratch is usually a symptom of hives or artificial urticaria.
Hives are caused by allergies, which is a generalized allergic reaction produced by the body’s sensitivity to certain items. Common allergens include mites, pollen, metals and seafood. The duration of urticaria is shorter than two months for acute urticaria and higher than two months for chronic urticaria.
Artificial urticaria, also known as cutaneous scratching disease, is characterized by localized raised red spots that appear like scratch marks when the skin is scratched. The cause of artificial urticaria is unknown, mainly related to heredity, the course of the disease is chronic, can be lifelong, prone to asthma, eczema, hives and other allergic diseases.
Patients with chronic urticaria or artificial urticaria are advised to check allergens once a year to determine what the body is allergic to, and to standardize the use of medication under the guidance of a doctor.