Gray nails, or onychomycosis, can occur in children. It is caused by a dermatophyte infection, which can often be transmitted to children through contact with relatives who have a fungal infection, etc. It can also be transmitted directly from tinea pedis. At the same time, the susceptibility of onychomycosis is related to systemic diseases such as diabetes mellitus, nail trauma, poor hygiene of the hands or feet, and localized blood and lymphatic reflux disorders. In daily life, you should pay attention to the regularity of work and rest, and exercise appropriately. At the same time, pay attention to hygiene and do not share towels, shoes and socks with others. If there is any discomfort, it is recommended to consult a doctor in time for diagnosis and treatment.