The differences between nasal and cerebrospinal fluid are different etiology, different character, and different composition. 1. Different etiologic factors: The cause of cerebrospinal fluid leakage is mostly skull fracture, usually with a history of obvious trauma. Nasal discharge is the secretion produced after infection by virus or bacteria, which is common in colds and rhinitis. 2. Different traits: cerebrospinal fluid is clearer and less viscous, while snot is more viscous and can be sticky. 3. Different composition: cerebrospinal fluid contains a certain amount of glucose, while snot does not contain glucose. In addition, patients with intracranial hemorrhage caused by trauma may be detected with blood cells in their cerebrospinal fluid, while most of the nasal mucus does not. If the patient can not distinguish between runny nose or cerebrospinal fluid, it is recommended to go to the hospital in a timely manner, to clarify the cause of the disease and then actively treat it.