Sudden headache with tearing eyes on one side may be related to cold stimulation, or it may be caused by cluster headache, glaucoma and other reasons. 1. Cold stimulation: common in cold winter, if the warm work is not done well, resulting in cold stimulation of the head and face, resulting in vasospasm and contraction of blood vessels in the head, which may cause sudden headache. Under the stimulation of cold wind, there may also be one or both sides of the eyes tearing phenomenon. 2. Cluster headache: this disease is a kind of autonomic headache, with the characteristics of periodic attacks, and its pain site is often fixed in the head and orbital area. When cluster headache attacks can appear sudden severe headache, also can be accompanied by one side of the eye tears, runny, upper eyelid drooping and other manifestations. 3. Glaucoma: When the acute attack of glaucoma causes the patient’s intraocular pressure to rise, the patient may have a sudden headache, one side of the eyes tearing, and may also be accompanied by light sensitivity, narrowing of the field of vision and other manifestations. Sudden headache with tearing in one eye may also be caused by other reasons. If symptoms persist, seek medical attention as soon as possible, and after diagnosis, treatment should be directed by a doctor.