The topical medications for the treatment of gray nails generally have fewer side effects on the body, there are certain side effects are internal drugs, the actual treatment needs to be used according to the condition, the specific adverse reactions to internal medication, as follows: 1, digestive discomfort: such as terbinafine tablets, ketoconazole tablets, etc. after taking, the most adverse reactions are nausea, vomiting, anorexia, etc., the general symptoms are mild, no need to be too nervous, after stopping the drug can be relieved. 2, skin allergic reactions: oral antifungal drugs, may appear light skin allergic reactions, such as rash, hives, etc., generally only once in a short period of time and disappear on their own, if the occurrence of progressive rash should be discontinued; 3, liver and kidney function damage: long-term use of antifungal drugs, will cause some damage to the liver and kidneys. The patient can use topical medication to treat gray nails to reduce the damage to liver and kidney function from oral medication. Patients who experience loss of appetite, fatigue, abdominal pain or deepening of urine color should stop the medication immediately and go to the hospital for liver and kidney function tests. Patients are advised to go to the hospital regularly for liver and kidney function, as well as grey nail checkups. Doctors will adjust the dosage of medication according to the liver and kidney function and disease recovery, to ensure the health of other tissues and organs in the body while achieving the purpose of treating the disease.