35.5 degrees is not considered a low fever, but a low fever is actually a fever scale. The general gradation of fever: low fever is 37.3-38 degrees; moderate fever is 38.1-39 degrees; high fever is 39.1-40 degrees; super high fever is 41 degrees or more. The common cause of fever is usually infectious fever. If it is accompanied by coughing and coughing, you can consider respiratory diseases, like upper respiratory tract infection, acute bronchitis, and pneumonia. If accompanied by abdominal pain, nausea, vomiting, you can consider digestive system diseases, like cholecystitis. If accompanied by symptoms of frequent and urgent urination, urinary system diseases, such as urinary tract infection, can be considered. The specific disease depends on the related accompanying symptoms, and it is best to visit the relevant departments of the hospital for a clear diagnosis and then further medication.