Sudden itchy feet are considered to be related to tinea pedis, contact dermatitis, urticaria and other diseases. 1. Tinea pedis: Tinea pedis is caused by infection of dermatophytes, such as Trichophyton rubrum and Trichophyton mustelii. Tinea pedis can cause some patients to have symptoms such as skin flaking, itchy skin, rough skin, etc. It can also cause some patients to have sudden itchy feet. 2. Contact dermatitis: contact dermatitis is related to contact with animal hair and chemical harmful substances. Disease will cause patients with local skin erythema, edema, papules and other symptoms, serious skin necrosis, ulcers and so on. Patients are conscious of local skin itching, burning sensation, swelling and pain, so there will also be a sudden itchy feet phenomenon. 3. Urticaria: urticaria is related to allergies, infections, autoimmune factors, can also cause some patients with sudden itchy feet. Patients are commonly manifested in the wind or angioedema, and the size of the wind, the shape varies, mostly accompanied by itching symptoms. Sudden itchy feet have other causes (such as eczema, etc.), if accompanied by other symptoms, should be timely medical treatment.