1.Sudden onset of headache; 2.Progressive worsening of headache; 3.Changing nature and degree of headache; 4.Headache with signs of systemic lesions (fever, neck tonicity, rash); 5.Headache with focal signs and symptoms of the nervous system (in addition to typical visual and sensory aura, such as hemiplegia, hemianesthesia, speech disorders, etc.); 6.Headache induced by coughing, exertion, upright position, etc.; 7.Headache during pregnancy or postpartum; 8.New onset of headache; 9.New onset of headache in cancer patients or AIDS patients.