What reason does skin itch scratch to rise a red pimple

The skin itch scratches a red pimple, often seen in the symptoms of urticaria. Urticaria is the skin mucosa due to temporary vascular permeability increased, and caused by localized edema. There are many reasons for urticaria, common are internal infections, such as fungal infection, bacterial infection, viral infection, parasite infection, etc., can cause urticaria. External allergenic factors, such as food, drugs, pollen, animal fur, dust mites, environment, friction, pressure, sunlight, etc. can also cause urticaria. Clinically, we should actively clarify the causes of urticaria, remove the causes and symptomatic treatment.