If your headache includes other symptoms, it may be a sign of a more severe condition, such as stroke, encephalitis, or meningitis. See a doctor immediately or call 911 if your headache also includes:[1] Trouble seeing, walking, or talking Stiff neck Nausea and/or vomiting High fever (102-104F) Fainting Difficulty using one side of your body Feelings of extreme weakness, numbness, or paralysis Also see a doctor if you have frequent or severe headaches, your medication doesn't work, or you can't function normally.