Many things may work quickly to resolve a headache: Lie down in a darker room, ease the pressure on your head by removing hair ties or clips, drink some water (since dehydration can sometimes cause head pain), consume a bit of caffeine, or take an OTC pain reliever such as acetaminophen (Tylenol), aspirin, ibuprofen (Advil, Motrin), or naproxen (Aleve). If your headache is persistent or becomes more severe, or if you have associated symptoms like vision changes, neck pain, fever, dizziness, vomiting, or if you pass out, see a doctor right away.