Grey nails, also known as onychomycosis and nail fungus, are clinically very common and are caused by a fungal infection of the nail, then it is contagious and there may be 1 grey nail infecting 2 or more nails. The actual nail is a very good way to get the most out of your nail. The most common medications are oral, such as itraconazole capsules or terbinafine tablets. The actual liver function must be normal to take oral medication, but you can also use topical medication for grey nails, such as Amorolfine application, which also has a good effect.