Gray fingernails is the medical term for onychomycosis, generally need to take terbinafine tablets for 1~3 months, serious condition, immunocompromised people need to extend the course of treatment up to half a year or more, and at the same time due to individual differences and different therapeutic effects, can not be sure of the specific duration of the medication. This disease is due to fungal infection caused by the disease, so the treatment should actively use antifungal agents, for the use of terbinafine tablets for patients, generally need to be taken continuously for 1~3 months. For people with more underlying diseases or older age, or those with severe onychomycosis, the course of treatment should be extended appropriately due to the lower resistance of their organisms compared to the general population, and can be extended to half a year and above if necessary. In the treatment at the same time should also pay attention to wear air permeable shoes, change and wash shoes and socks diligently, eat less spicy and stimulating food, increase the intake of fresh vegetables and fruits appropriately, keep a happy mood, if the symptoms continue to be unrelieved, it is recommended that the patient go to a regular hospital, after clarifying the cause of the disease under the guidance of the doctor to actively treat it, and pay attention to monitoring the function of the liver and kidneys.