Hollow toenails may be related to trauma, onychomycosis, nail malnutrition and other reasons. 1. Trauma: when the toenail is accidentally squeezed or smashed, resulting in damage to the nail bed, it is likely to lead to the separation of the nail bed from the nail plate, and the phenomenon of empty toenails may occur. 2. ringworm of the nail: usually caused by fungal infection of the toenail, under the constant stimulation of the pathogenic bacteria, it is likely to lead to the damage of the diseased toenail, which may cause the separation of the nail bed and the nail plate over time, thus causing the toenail to be empty. 3. Nail malnutrition: usually due to irregular diet, picky eating and other reasons, resulting in nail malnutrition, may cause the toenail hollow, may also be accompanied by thinning, brittle toenails, nail shedding and other manifestations. Hollow toenails may also be caused by other reasons, it is recommended to consult a doctor as soon as possible to clarify the cause, and then give targeted treatment and conditioning.