1. The first cause of chronic urticaria is genetic factors, such as familial cold urticaria. 2. Amaranth: Many amaranth often cause chronic urticaria. 3. Food: fish, shrimp, crab, eggs, milk and other common factors that cause chronic urticaria that contain special proteins. 4. Infection: The cause of chronic urticaria. Bacterial infection, viral infection, fungal infection and parasites can cause chronic urticaria. Insect bites such as mites, fleas, bed bugs, etc. 5. Inhaled substances: Various pollen, dust, etc. can cause urticaria. 6. Physical and chemical factors: Physical and mechanical stimulation such as cold, heat, sunlight, friction and pressure, or certain chemical substances entering the human body can cause urticaria. 7. Medical diseases: Lymphoma, cancer, hyperthyroidism, rheumatism and rheumatoid arthritis, SLE, hyperlipidemia, cholecystitis, nephritis, liver disease, diabetes, etc. can cause urticaria. 8. Mental factors and endocrine changes: Urticaria caused by mental stress, emotional impulse, menstruation, menopause, pregnancy, etc. Chronic urticaria caused by allergic reactions