Acute urticaria is divided into acute and chronic. Acute urticaria usually subsides within 2-24 hours; chronic urticaria is more stubborn, prone to recurrent attacks and difficult to heal on its own. Urticaria is acute within 6 weeks after the onset of urticaria, and chronic urticaria is more than 6 weeks after the onset of urticaria. The cause is complex and unknown in most patients. The common causes are food or drug allergy, insect bites, genetic factors, external stimuli, mental factors and endocrine changes. If the cause can be clearly identified, timely treatment of the cause, usually with a short period of time may be self-healing. For example, hives caused by drug or food allergies can usually heal themselves in about 1-2 weeks after stopping use and intake. Chronic urticaria, on the other hand, is often difficult to heal on its own in the short term and requires treatment to control the symptoms. Patients with urticaria are advised to visit a hospital dermatologist in a timely manner and try to standardize treatment for the cause to prevent delays.