Gray nails are a common fungal disease caused by a fungal infection of the nail plate and subnail tissues. Patients are generally not advised to apply so-called prescriptions and also other medications for gray nail treatment. Ten drops of water is indeed a drug in the clinic, but it does not have the effect of treating fungus and curing gray nails. When applied to the surface of gray nails, 10 drops of water cannot penetrate the thick nail to remove the fungus. Even if you apply 10 drops of water as tincture of iodine, cyclopiazone and other medications, and apply them to the thin nail, they can not play a better role in killing the fungus. Therefore, patients should go to the dermatology department of a regular tertiary care hospital after getting gray nails.