Thickening and yellowing of the toenails is mostly considered to be caused by nail fungus disease. Fungi such as dermatophytes, yeasts or molds cause nail fungal disease after infecting the subnail tissues or nail plate, and are mostly directly transmitted by tinea pedis. Among nail fungal diseases, the distal lateral subnail type is the most common, where the fungus invades the distal anterior and lateral edges of the nail, which can cause the nail surface to be uneven or broken, with thickening or a grayish-yellowish cloudy color. The end result can be destruction of the entire nail plate, thickening, grayish-yellow, and even loss. Found toenail yellowing and thickening or other pathological changes recommended timely to the hospital specialist, under the guidance of the doctor for treatment; usually wear breathable shoes and socks, living supplies and other people separate use to avoid infecting other people.