Headache without fever is not considered to be encephalitis. Encephalitis is a viral infectious disease, patients mainly manifested as headache, fever, body temperature between 37-39 ℃, individual patients can also be as high as 40 ℃, can appear headache, at the same time, can appear somatic, neurological dysfunction, such as hemiplegia, hemiplegia, hemiplegia and hemiplegia sensory deficits, but also can appear in the speech dysfunction. In the case of lobar lesions, psychiatric symptoms can also occur, and some patients may also experience seizures. In patients with encephalitis, the diagnosis is mainly based on an electroencephalogram and cerebrospinal fluid pathogenetic tests. Treatment is mainly antiviral, but also cranial pressure reduction as well as improvement of blood circulation and cerebral metabolism can be given. If the patient has a headache without fever, cerebrovascular disease can be considered, as well as brain tumors. In addition, it can also be seen in neurological diseases, such as neurological headache or tension headache and migraine, etc. The treatment of this disease is mainly to give symptomatic treatment.