Suddenly getting hives may be related to environmental factors, dietary factors, disease factors and so on. 1. Environmental factors: If you are in an environment with more plants, it may lead to pollen allergy or mosquito bites, which may induce hives. If the living environment is not clean and tidy, it may come into contact with animal hair, dust mites and other allergens, which may also induce hives. 2. Dietary factors: If you eat fish, shrimp, milk and other animal protein foods, or salicylates, lemon yellow and other food additives, may cause food allergies, thus triggering hives. 3. Disease factors: If you suffer from viral upper respiratory tract infections, such as acute rhinitis, pharyngitis, tonsillitis and other diseases, may induce urticaria. If urticaria occurs, it is recommended to consult a doctor for a clear diagnosis of the cause of the disease, and then targeted treatment, so as not to delay the condition.