The causes of headache and fever include infections outside the central nervous system and intracranial infections. 1. Infections outside the central nervous system: for example, upper respiratory tract infections, mainly due to bacterial and viral infections, the onset of inflammatory factors due to the invasion of the patient may have a headache, fever symptoms. 2. Intracranial infections: including bacterial encephalitis or meningitis, viral encephalitis or meningitis. Due to the infectious factors cause fever symptoms, at the same time due to the emergence of cerebral edema, increased cranial pressure, and the performance of headache, nausea, vomiting, serious can be lethargy, coma and so on. Headache and fever are recommended to go to the hospital in a timely manner, under the guidance of professional doctors and reasonable treatment.