When washing yam, the surface of yam and yam type will contain a kind of plant alkali, which will irritate the skin and cause skin irritation or allergy symptoms. If you have allergic symptoms when washing yam, you must promptly get rid of the yam in contact with it and rinse your hands with water. In addition, you must also try to avoid spicy and irritating food, and avoid excessive scratching of the local area, which may further aggravate the itching.