Headache is pain in any region of the head. Headaches may occur on one or both sides of the head, be isolated to a certain location, radiate across the head from one point, or have a viselike quality.
A headache may appear as a sharp pain, a throbbing sensation or a dull ache. Headaches can develop gradually or suddenly, and may last from less than an hour to several days.
Your headache symptoms can help your doctor determine its cause and the appropriate treatment. Most headaches aren't the result of a serious illness, but some may result from a life-threatening condition requiring emergency care.
Headaches are generally classified by cause:
A primary headache is caused by overactivity of or problems with pain-sensitive structures in your head. A primary headache isn't a symptom of an underlying disease.
Chemical activity in your brain, the nerves or blood vessels surrounding your skull, or the muscles of your head and neck (or some combination of these factors) can play a role in primary headaches. Some people may also carry genes that make them more likely to develop such headaches.
The most common primary headaches are:
A few headache patterns also are generally considered types of primary headache, but are less common. These headaches have distinct features, such as an unusual duration or pain associated with a certain activity.
Although generally considered primary, each could be a symptom of an underlying disease. They include:
Some primary headaches can be triggered by lifestyle factors, including:
A secondary headache is a symptom of a disease that can activate the pain-sensitive nerves of the head. Any number of conditions — varying greatly in severity — may cause secondary headaches.
Possible causes of secondary headaches include:
Some types of secondary headaches include:
A headache can be a symptom of a serious condition, such as a stroke, meningitis or encephalitis.
Go to a hospital emergency room or call 911 or your local emergency number if you're experiencing the worst headache of your life, a sudden, severe headache or a headache accompanied by:
See a doctor if you experience headaches that: