The causes of frequent left-sided headache are as follows: a. Left-sided migraine attack, the patient has a history of migraine, due to exertion, tension, poor rest or eating strong tea, coffee, red wine, etc. trigger migraine attacks resulting in left-sided headache, accompanied by nausea, photophobia, tearing, etc. in severe cases. Second, the left headache is caused by left eye lesions, such as increased pressure in the left eye, glaucoma and left eye visual fatigue, etc. If necessary, consult an ophthalmologist. Third, headache is caused by sinusitis in the left side of the nose, and headache symptoms are heavier after a cold, so consult the ear, nose and throat department if necessary. Four, cerebral arteriosclerosis, cerebral vascular spasm caused by vascular spasm makes patients appear headache, accompanied by dizziness when serious. V. Intracranial occupational disease causes left headache, and the symptoms are heavier in the morning when waking up, and the lesion can be found after CT or MRI examination.