Patients with left eye pain and left headache consider the following causes: 1. If the patient has intensive attacks of left headache over a period of time, consider it to be caused by cluster headache. Cluster headache belongs to vascular headache, and the patient will show severe pain or soreness around one side of the eye, accompanied by tearing, sweating and runny nose. The patient’s ipsilateral eye will have conjunctival congestion and eye pain, along with nasal congestion on the affected side, which will lead to nausea and vomiting in severe cases. 2. The patient’s left eye pain and left headache may also be caused by ophthalmological diseases, such as glaucoma in the left eye, and elevated intraocular pressure will cause the patient to have eye pain along with headache symptoms.