Gray nails in medicine generally refers to onychomycosis, onychomycosis causes the nails to become yellow and empty place can be cut off, cut off can be applied externally ketoconazole ointment, internal antifungal drugs and so on. 1. ringworm of the nails is generally due to fungal infection caused by invasion of the nail plate, there can be structural deformation of the nails, the nails will become cloudy, thickening or brittle, yellow, and in severe cases there will be a separation of the nails and the nail bed. 2. Nail fungus leads to nail thickening, yellow and empty, at this time in the surface application of antifungal drugs is not obvious, need to cut off the damaged nails, expose the nail, and then apply antifungal drugs, such as ketoconazole cream, can also be used with oral itraconazole capsules and so on. The medication should be used in accordance with the doctor’s instructions. It is recommended that patients with onychomycosis be treated under the guidance of a physician and not blindly self-medication to avoid adverse reactions.