What causes allergic urticaria?

Allergic urticaria is a skin allergic reaction caused by the combined effects of various internal and external factors. The main causes include: 1. Allergen exposure: Such as animal proteins in food (e.g., fish, shrimp, crab, milk, eggs), plant-based foods (e.g., strawberries, mushrooms), and food additives; medications such as penicillin, serum products, and vaccines; inhalants such as pollen and dust mites; and substances that come into contact with the skin such as insect venom and hair dyes. 2. Infectious factors: Infections caused by various viruses, bacteria, fungi, and parasites. These pathogens and their metabolic products may trigger allergic reactions. 3. Physical factors: Physical stimuli such as cold, heat, sunlight, friction, and pressure may also lead to the occurrence of physical urticaria. 4. Psychological and endocrine factors: Emotional fluctuations, stress, depression, and other psychological factors, as well as changes in the endocrine system, may also act as triggers for urticaria. 5. Genetic factors: Some patients with urticaria may have a familial genetic predisposition, such as familial cold urticaria.