What causes headaches and when should you see a doctor?

Headaches are caused by a wide range of factors including tension and muscle tightness, dehydration, lack of sleep, stress, caffeine withdrawal, sinus congestion, eye strain, and hormonal changes. Migraines involve neurological changes that cause throbbing pain, often with nausea and light sensitivity. Secondary headaches can stem from underlying conditions like high blood pressure or infections. You should see a doctor if headaches are sudden and severe, described as the worst of your life, or accompanied by fever, stiff neck, confusion, vision changes, or weakness, as these can signal serious conditions like meningitis or stroke. Also seek care if headaches are frequent, worsening over time, or not responding to over-the-counter pain relievers.