Onychomycosis and tinea unguium refer to the same disease, with no differences between the two. Also known as tinea unguium or onychomycosis, it is caused by fungal infections and is characterized by symptoms such as thickening, yellowing, defects, or deformities of the nails. Once onychomycosis occurs, it is crucial to seek timely treatment because it is contagious. It can spread among individuals through direct or indirect contact, and it has relatively strong infectivity. Therefore, prompt treatment of onychomycosis is very important.