Gray nails are mostly caused by fungal infections, which are also contagious because they are more reproductive and have more modes of transmission. In terms of transmission routes, gray nails are mainly contagious by contact. For example, if a person has a fungal infection of the feet, if he or she is not careful and often uses his or her hands to clean his or her feet, the fungus will infect the hands, and soon afterwards, the nails of both hands will also be infected with gray nails. In everyday life, there are more ways for healthy people to get infected with gray nails. If a person has tinea corporis in other parts of the body, such as the skin, and the person scratches the affected area with his or her hands, the fungus can infect the hands, and if there are wounds on the hands, the person may also develop gray nails. It is also easy to catch the fungus in some public places, such as grabbing bus rings, going to public bathrooms and swimming pools, etc. In addition, direct contact with the shoes and socks of people with gray nails can also cause infection. To avoid infecting other healthy nails and others with gray nails, patients should actively treat their nails by taking orally or quoting some antifungal medications. In addition, the use of rice vinegar to soak the affected area for half an hour a day can also have some auxiliary effect. Grey nails are mainly transmitted by contact. If healthy nails come in contact with pathogenic fungus, it may lead to infection and disease, so prevention should be strengthened and treatment should be carried out after the disease.