Nails of the toes (normally written as toes) become white, considering that it is caused by nail fungus disease, psoriasis and other diseases. 1. Nail fungus disease: Nail fungus disease is a nail lesion caused by fungi invading the nail bed, and the typical symptoms of patients are cloudy, thickened or brittle nail plate, discoloration, and shedding, etc. If the foot suffers from nail fungus disease, the toenail will turn white. 2. Psoriasis: Psoriasis is caused by the interaction of many factors, and the typical symptom is red spots on the skin covered with silver-white scales. If psoriasis leads to nail involvement, it will lead to toenail damage, which is manifested as point-like depression on the nail plate, unequal nail plate, and whitening of toenails in some patients. White toenails should be examined by a doctor to clarify the diagnosis and choose the appropriate way to deal with it.