Nail bruises do not belong to gray nails. Nail bruises are mostly due to subcutaneous capillary rupture caused by subcutaneous bruises, and trauma-related, may also be due to purpura and other diseases caused by subcutaneous capillary rupture; gray nail is a fungal infection caused by onychomycosis, so simple nail bruises do not belong to gray nail. If there is trauma to the nail and it comes into contact with fungus, it may induce fungal infection and cause diseases such as onychomycosis. If the nail bruises caused by trauma, generally within 48 hours of cold compresses, more than 48 hours of hot compresses, most of them will recover on their own, usually without special treatment. If it is a fungal infection caused by gray nails, you should go to the regular hospital dermatology examination as soon as possible, after a clear diagnosis, under the guidance of the doctor standardized treatment.