5. Excessive tearing
Another function of the trigeminal nerve is associated with the production of tears. Since migraine patients usually have an alteration in the trigeminal nerve, it becomes overactive and triggers excessive tearing, even if there’s no foreign object to clear in the eyes. Excessive tearing is unilateral, which means only one eye is affected by this condition, and it usually has conjunctival hyperemia and associated ocular pain in the same side of the head.