Gray nails are a common fungal disease caused by a fungal infection of the nail plate and the tissue underneath the nail. Patients with gray nails often have mild symptoms in the early stages, for example, they may notice one or more white patches under the nails, but the white patches do not cause any sensation to the patient. Patients may also notice that their nails are uneven, lose their luster, and may have hollow nails. These white patches can often turn grayish-yellow as the disease progresses, and patients may experience significant thickening of the nails and flaking or breaking of the surrounding area as the disease progresses.