Headache and fever can be caused by infectious diseases, most commonly seen clinically in central nervous system infections, including encephalitis and meningitis. Most encephalitis is caused by viral infections, and patients mainly present with physical signs and symptoms, which can include sensory impairment of the limbs, motor dysfunction, and possibly dizziness and balance disorders. Some patients can have seizures and may also have psychiatric symptoms, depending mainly on the site of lesion involvement. In severe cases, patients can also develop impaired consciousness, and they can also develop fever, headache, nausea, and vomiting. The main treatment is antiviral therapy, and the commonly used drugs are acyclovir and ganciclovir. If there is an increase in intracranial pressure, cranial pressure should be lowered with the application of mannitol and glycerol fructose. If there is impaired consciousness, brain-awakening treatment can be given, and commonly used drugs include brain-awakening sedative and compound musk. In case of meningitis, which is caused by bacterial infection, most of the patients can have headache, fever, nausea, vomiting, and can have signs of meningeal irritation, which are mainly treated with antibacterial therapy.