Overview of Headache

The two most common causes of headache are primary headaches:

Less often, headaches are due to a less common primary headache disorder called cluster headache Cluster Headaches A cluster headache causes severe pain that is felt at the temple or around the eye on one side of the head and that lasts a relatively short time (usually 30 minutes to 1 hour). It is accompanied... read more or to one of the many secondary headache disorders (see table Some Causes and Features of Headaches Some Causes and Features of Headaches ). Some secondary headache disorders are serious, particularly those that involve the brain, such as meningitis Introduction to Meningitis Meningitis is inflammation of the layers of tissue that cover the brain and spinal cord (meninges) and of the fluid-filled space between the meninges (subarachnoid space). Meningitis can be... read more , a brain tumor Overview of Brain Tumors A brain tumor can be a noncancerous (benign) or cancerous (malignant) growth in the brain. It may originate in the brain or have spread (metastasized) to the brain from another part of the body... read more , or bleeding within the brain (intracerebral hemorrhage Intracerebral Hemorrhage An intracerebral hemorrhage is bleeding within the brain. Intracerebral hemorrhage usually results from chronic high blood pressure. The first symptom is often a severe headache. Diagnosis is... read more ).

Fever can cause headaches, as can many infections that do not specifically involve the brain. Such infections include Lyme disease Lyme Disease Lyme disease is a tick-transmitted infection caused by Borrelia species, primarily by Borrelia burgdorferi and sometimes by Borrelia mayonii in the United States. These... read more , Rocky Mountain spotted fever Rocky Mountain Spotted Fever (RMSF) Rocky Mountain spotted fever is a potentially fatal rickettsial infection that is transmitted by dog ticks and wood ticks. It causes a rash, headache, and high fever. People become infected... read more , and influenza Influenza (Flu) Influenza (flu) is a viral infection of the lungs and airways with one of the influenza viruses. It causes a fever, runny nose, sore throat, cough, headache, muscle aches (myalgias), and a general... read more .

Headaches also commonly occur when people stop consuming caffeine or stop taking pain relievers (analgesics) after using them for a long time (called medication overuse headache Medication Overuse Headache A medication overuse (rebound) headache occurs when people who take too many headache drugs have a headache for more than 15 days a month for more than 3 months. Medication overuse headache... read more ).

Contrary to what most people think, eye strain and high blood pressure (except for extremely high blood pressure) do not typically cause headaches.

In people with headaches, certain characteristics are cause for concern:

People who have any warning sign should see a doctor immediately. The presence of a warning sign may suggest that the headaches may be caused by a serious disorder, as for the following:

If people with none of the above symptoms or characteristics start having headaches that are different from any they have had before or if their usual headaches become unusually severe, they should call their doctor. Depending on their other symptoms, the doctor may ask them to come for an evaluation.

Doctors first ask questions about the person's symptoms and medical history. Doctors then do a physical examination. What they find during the history and physical examination often suggests a cause of the pain and tests that may need to be done (see table Some Causes and Features of Headaches Some Causes and Features of Headaches ).

Doctors ask about the characteristics of the headache:

Other questions may include

Doctors also ask about risk factors for headache. They include

People can think about how to answer the above questions and write the answers down before they go to the doctor. Sometimes doctors ask people to fill out a headache questionnaire that covers most of the relevant questions. People may complete the questionnaire before their visit and bring the results with them. Having this information written down can save time and help guide the evaluation.

A general physical examination is done. It focuses on the head and neck and on brain, spinal cord, and nerve function (neurologic examination Neurologic Examination When a neurologic disorder is suspected, doctors usually evaluate all of the body systems during the physical examination, but they focus on the nervous system. Examination of the nervous system—the... read more ). An eye examination The Eye Examination A person who has eye symptoms should be checked by a doctor. However, some eye disorders cause few or no symptoms in their early stages, so the eyes should be checked regularly (every 1 to 2... read more is sometimes also done.

Most people do not need testing. However, if doctors suspect a serious disorder, tests are done. For some suspected disorders, tests are done as soon as possible. In other cases, testing can be done within one or more days.

Magnetic resonance imaging (MRI) and/or magnetic resonance angiography (which provides detailed images of blood vessels) or, if MRI is not available or contraindicated, computed tomography (CT) is done as soon as possible if people have

If people have a thunderclap headache, magnetic resonance angiography Magnetic resonance angiography (MRA) In magnetic resonance imaging (MRI), a strong magnetic field and very high frequency radio waves are used to produce highly detailed images. MRI does not use x-rays and is usually very safe... read more is done immediately.

MRI is done within a day or so if people have conditions such as the following:

MRI or CT (if MRI is not available or is contraindicated) is done within a few days if people have certain other characteristics, such as the following:

A spinal tap Spinal Tap Diagnostic procedures may be needed to confirm a diagnosis suggested by the medical history and neurologic examination. Electroencephalography (EEG) is a simple, painless procedure in which... read more (lumbar puncture) is usually done if

Usually, doctors do CT or MRI before the spinal tap if they think that pressure within the skull may be increased—for example, by a mass (such as a tumor, an abscess, or a hematoma). A spinal tap can be dangerous if pressure within the skull is increased. When spinal fluid is removed and pressure within the skull is increased, parts of the brain may suddenly shift downward. If these parts are pressed through the small openings in the tissues that separate the brain into compartments, a life-threatening disorder called brain herniation Herniation: The Brain Under Pressure results.

Other tests are done within hours or days, depending on the examination results and the causes that are suspected.