What actually causes headaches?

The brain tissue itself has no pain receptors, so headaches originate in the structures around it: blood vessels, the meninges covering the brain, muscles of the head, neck, and scalp, and cranial nerves. Tension-type headaches are by far the most common, typically felt as a band of pressure on both sides, and are associated with muscle tension, stress, poor posture, and jaw clenching. Migraines are a distinct neurological condition involving abnormal brain activity affecting nerve signaling and blood vessels, usually one-sided and throbbing, often with nausea and light sensitivity, and sometimes preceded by visual aura. Cluster headaches, far rarer, produce severe pain around one eye in bouts.

Common triggers worth auditing before reaching for medication: dehydration, skipped meals, sleep disruption in either direction, caffeine, particularly withdrawal from a regular habit, alcohol, eye strain, and stress. A frequently missed cause is medication overuse headache, where taking pain relievers more than about two or three days a week creates a rebound cycle that sustains the headaches being treated. The symptoms that warrant urgent medical attention rather than home management are worth knowing: a sudden severe headache reaching maximum intensity within seconds, a headache with fever and stiff neck, confusion, weakness, vision loss, or slurred speech, one following head injury, or a distinct change in the pattern of headaches you usually get.