What causes red lumps on the inner thigh itching?

Urticaria is a localized edematous reaction caused by reactive expansion and increased permeability of small blood vessels in the skin and mucosa. The etiology of most patients is unknown, especially chronic urticaria. The causes are as follows: 1. Food, mainly including animal protein, plants and certain food additives;2. Drugs, many drugs can cause hypersensitivity reactions in the body; 3. Infection, including various bacteria, fungi, viruses, parasites and other infections;4. Physical factors;5. Animal and plant factors;6. Mental factors;7. Secondary to visceral and systemic diseases;8. Other factors, inhalants, pregnancy or menstrual cycle, etc.