Can drinking a lot of water give you headache?

Yes.: Drinking too much water can cause headache, as well as a serious condition called "water intoxication." if you drink much more plain water than you lose through sweat, urination and evaporation of exhaled air, your blood can become so dilute (hypotonic) that water moves into your cells, causing them to swell. Swelling of brain cells specifically can cause seizure coma, even death.