The common causes of itchy legs include papular urticaria, eczema, contact dermatitis and so on. 1. Pemphigus urticaria: most of the onset of the main insect bites, such as mosquitoes, bedbugs, fleas, lice, mites, midges and other bites caused by an allergic reaction, itching when scratching the skin will appear red dots. 2. Eczema: the etiology of this disease is unknown, may be related to chronic infection foci, endocrine and metabolic changes, blood circulation disorders, food, inhalants and other factors, manifested as intense itching of the skin, red pimples and other symptoms. 3. Contact dermatitis: this disease is mainly caused by primary irritants, such as sulfuric acid, nitric acid, sodium hydroxide, salicylic acid, etc., as well as contact sensitizers, such as formaldehyde, rubber products, cyclic resins, facial wipes and other factors. Manifested as erythema, small papules, intense itching and other symptoms, when scratching the skin, localized red dots or erythema and other symptoms. It is recommended that patients go to the dermatology department of regular hospitals, follow the doctor’s instructions to clarify the diagnosis, reasonable treatment, to avoid delaying the condition.