Headache with low blood pressure is usually seen as a low cranial pressure headache. Causes of this disorder include cerebrospinal fluid leakage, dehydration, systemic infectious diseases, uremia, central nervous system infections, etc. These disorders result in a decrease in cerebrospinal fluid volume, and the lowered cranial pressure causes headaches due to the strain on the cerebral nerves. Low cranial pressure headache is characterized by headache with lower blood pressure in sitting or standing position, and the headache can be relieved or disappeared after lying down, and the blood pressure returns to normal. The nature of the headache is bilateral frontal or temporo-occipital dull pain and pulsating pain, which may be accompanied by nausea, vomiting, dizziness, tinnitus and other symptoms. In these patients, the headache symptoms can be improved after a period of heavy fluid replacement and bed rest.