Onychomycosis, also known as tinea unguium, refers to the same condition, which is a disease caused by fungal infection of the nails. Once affected by onychomycosis or tinea unguium, the nails may thicken, turn yellow, flake irregularly, and become deformed. If tested in a hospital, the fungus may test positive. Therefore, after contracting onychomycosis or tinea unguium, it is crucial to maintain personal hygiene, cut off sources of infection, and ensure that used items are disinfected.