Headache in the following cases should be seen as soon as possible: 1. All secondary headache, i.e. symptomatic headache, headache accompanied by symptoms, should be seen as soon as possible to clarify the primary cause and give correct and timely treatment; 2. Severe headache that is significantly different from the previous one; 3. Gradual progression of headache with possible intracranial tumor or other diseases; 4. Headache with fever; 5. Headache with limb and facial numbness, i.e. other neurological symptoms in addition to headache; 6. History of tumor, such as lung cancer, gastrointestinal cancer with headache and suspected intracranial metastasis.