After an outbreak of urticaria, it usually fades away in about 2-3 hours. Urticaria belongs to an allergic disease, which is caused by an allergic substance that induces the body to produce IgE, the antibody binds to the corresponding receptors on the surface of mast cells and basophils, leaving the body in a state of sensitization to the allergic substance. When the same allergic substance enters the body again, it releases a series of bioactive substances, such as histamine, by binding specifically to the antibodies on the surface of the sensitized mast cells or basophils When the same allergenic substance enters the body again, it releases a series of bioactive substances, such as histamine, which can cause small blood vessel dilation, increased permeability, smooth muscle contraction and increased glandular secretion, resulting in a series of local or systemic allergic symptoms in the skin, mucous membranes, respiratory and digestive tracts. The disease is generally characterized by a rapid appearance and fading, with the outbreak subsiding within 2-3 hours, allowing the skin surface to return to normal. After the outbreak subsides, the skin surface is consistent with normal skin and no pigmentation abnormalities are usually left. When you have hives, it is best to go to the hospital and use desensitizing drugs for oral treatment under the guidance of a doctor. If the itching is obvious, you can also use topical medications such as stove glycolic lotion to relieve the itching symptoms.