Like to bite fingernails, there are several types of diseases as follows: First, the lack of vitamins and trace elements in the body caused by the lack of zinc in the body and can be omnivorous, omnivorous including like to bite their fingernails, like to eat strange things, but strange things are not contain food. Therefore, if you like to bite your fingernails, you should quickly find out whether there is a deficiency of trace elements in your body, and if there is a deficiency of zinc ions, you should quickly give supplements. Second, for patients who have had a history of cerebrovascular disease, such as previous epilepsy or the emergence of encephalitis, encephalomyelitis or the emergence of viral encephalitis, septic encephalitis and other diseases past history, patients will also appear, involuntary abnormal neuronal discharges and abnormal impulses in the nervous system, some will remain like biting fingernails, biting hands and other undesirable sequelae occur.