Gray nails, clinically known as onychomycosis, is a disease caused by a fungal infection that can occur on both the hands and the feet. Currently, topical medication is the main treatment for onychomycosis, and sometimes oral medication is required to treat it. You should follow your doctor’s instructions and choose a combination of topical and internal medication when your condition requires it: 1. Topical medication: When the fungal infection involves the distal nail, you can apply glacial acetic acid and tincture of iodine externally, soaking it in warm water before using the medication, and then using a tool to scrape the diseased nail part off the nail for better efficacy. Salicylic acid ointment and urea ointment can also be applied externally and then wrapped with gauze, which can soften the diseased nail better and promote its self-exfoliation. In addition, you can also use local antifungal drugs for treatment, such as amorolfine hydrochloride application, cypionamide cream, etc.; 2. Internal medication: such as oral metronidazole, itraconazole, terbinafine, etc., also have some effect on fungal infection. Medication should be used under the guidance of a doctor. For the treatment of nail fungus, in addition to applying medications, one should also pay attention to the usual daily care. If the patient has toenail infection of the foot, he should keep the foot clean, wear cotton socks, shoes should be of the right size and not too tight, do not walk barefoot, and do not cut the toenail too short to avoid re-traumatization of the foot. If you have nail fungus of the hands, you should avoid contact with others and protect your hands well to avoid infecting others or your feet.