Gray nails, also known as onychomycosis, are a common dermatologic condition and should be seen in a dermatologist. Gray nail refers to the lesions caused by the red fungus, Trichophyton rubrum, Trichophyton mustelii and other dermatophytes that invade the nail plate or (and) the nail bed, which belongs to a kind of nail fungal disease, mainly manifested as the thickening of the diseased nail, separating, clouding, discoloration, surface unevenness, atrophy, and shedding, and so on. Gray nail is a common dermatological disease, and the disease is contagious, can be transmitted through contact, so should go to the dermatologist in time. Nail fungus can be applied topically with antifungal drugs such as amorolfine application, and combined with oral antifungal drugs such as terbinafine and itraconazole can improve the efficacy. Patients with gray nails should go to the dermatologist in time, follow the doctor’s instructions for targeting and treatment, and avoid blindly using medication on their own, so as not to delay the condition.