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Overview of Headache

By Stephen D. Silberstein, MD, Professor of Neurology and Director, Headache Center, Sidney Kimmel Medical College at Thomas Jefferson University

A headache is pain in any part of the head, including the scalp, upper neck, face, and interior of the head. Headaches are one of the most common reasons people visit a doctor.

Headaches interfere with the ability to work and do daily tasks. Some people have frequent headaches. Other people hardly ever have them.


Although headaches can be painful and distressing, they are rarely due to a serious condition. Headaches can be divided into two types:

  • Primary headaches: Not caused by another disorder

  • Secondary headaches: Caused by another disorder

Primary headache disorders include migraine, cluster headache, and tension-type headache.

Secondary headaches may result from disorders of the brain, eyes, nose, throat, sinuses, teeth, jaws, ears, or neck or from a bodywide (systemic) disorder.

Common causes

The two most common causes of headache are primary headaches:

Less common causes

Less often, headaches are due to a less common primary headache disorder called cluster headache or to one of the many secondary headache disorders (see Table: Some Causes and Features of Headaches). Some secondary headache disorders are serious, particularly those that involve the brain, such as meningitis, a brain tumor, or bleeding within the brain (intracerebral hemorrhage).

Fever can cause headaches, as can many infections that do not specifically involve the brain. Such infections include Lyme disease, Rocky Mountain spotted fever, and influenza.

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).

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


Doctors focus on determining whether the headache has another cause (that is, whether it is a secondary headache). They also check for symptoms suggesting that the headache is caused by a serious disorder. If no cause is identified, they focus on identifying which type of primary headache is present.

Warning signs

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

  • Changes in sensation or vision, sudden weakness, loss of coordination, seizures, difficulty speaking or understanding speech, or changes in levels of consciousness such as drowsiness or confusion (suggesting a brain disorder)

  • A fever and a stiff neck that makes lowering the chin to the chest painful and sometimes impossible

  • A very sudden, severe headache (thunderclap headache)

  • Tenderness at the temple (as when combing hair) or jaw pain when chewing

  • The presence of cancer or a disorder that weakens the immune system (immunodeficiency disorder)

  • Use of a drug that suppresses the immune system

  • Symptoms that affect the whole body such as fever or weight loss

  • A headache that progressively worsens

  • Red eyes and halos seen around lights

When to see a doctor

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:

  • A severe headache with a fever and a stiff neck: Meningitis—a life-threatening infection of the fluid-filled space between the tissues covering the brain and spinal cord (meninges)

  • A thunderclap headache: A subarachnoid hemorrhage (bleeding within the meninges), which is often due to a ruptured aneurysm

  • Tenderness at the temple, particularly in older people who have lost weight and have muscle aches: Giant cell arteritis

  • Headaches in people who have cancer or a weakened immune system (due to a disorder or drug): Meningitis or spread of cancer to the brain

  • Red eyes and halos seen around lights: Glaucoma, which, if untreated, leads to irreversible loss of vision

People without warning signs but with certain other symptoms require prompt evaluation within a few days to a week. These symptoms include

  • Headaches that increase in frequency or severity

  • Headaches that begin after age 50

  • Worsening vision

  • Weight loss

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 advise taking an analgesic or ask them to come for an evaluation.

What the doctor does

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).

Doctors ask about the characteristics of the headache:

  • How often it occurs

  • How long it lasts

  • Where the pain is

  • How severe is it

  • Whether any symptoms accompany it

  • How long a sudden headache takes to reach its maximum intensity

  • What triggers the headache, what makes it worse, and what relieves it

Other questions may include

  • Whether people have had headaches before

  • Whether the headaches recur and, if so, when did they start and how often do they occur

  • Whether the current headache is the same or different from previous headaches

Doctors also ask about risk factors for headache. They include

  • Whether people take or have stopped taking certain drugs

  • Whether they have had a spinal tap recently

  • Whether they have a disorder that may account for the headache

  • Whether they have family members with severe headaches

  • Whether they have had a recent head injury

People can think about how to answer the above questions and write the answers down before they go to the doctor. Doing so can save time and help guide the evaluation.

A general physical examination is done. It focuses on the head and neck and on the brain, spinal cord, and nerves (neurologic examination).


Most people do not need testing. However, if doctors suspect a serious disorder, tests are usually 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) or computed tomography (CT) is done as soon as possible if people have

  • A thunderclap headache

  • Changes in levels of consciousness, such as drowsiness or confusion

  • A fever and a stiff neck that makes lowering the chin to the chest painful and sometimes impossible

  • Swelling of the optic nerve, detected by eye examination with an ophthalmoscope

  • Symptoms that suggest a serious bodywide response to an infection (sepsis), such as a certain type of rash or shock

  • Symptoms that suggest a brain disorder, such as changes in sensation or vision, sudden weakness, loss of coordination, seizures, or difficulty speaking or understanding speech

  • Extremely high blood pressure

  • A head injury causing headache and loss of consciousness

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

  • Cancer

  • A weakened immune system (due to a disorder such as AIDS or a drug)

MRI or CT is done within a few days if people have certain other characteristics, such as the following:

  • Headaches that begin after age 50

  • Weight loss

  • Double vision

  • A new headache that is worse when the person awakens in the morning or that awakens the person from sleep

  • An increase in the frequency, duration, or intensity of chronic headaches

A spinal tap (lumbar puncture) is usually done if

  • Acute meningitis or encephalitis (a brain infection) is suspected.

  • People have a thunderclap headache (suggesting subarachnoid hemorrhage) even when the results of CT or MRI are normal.

  • People have a weakened immune system.

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 results (see Herniation: The Brain Under Pressure).

Other tests are done within hours or days, depending on the examination results and the causes that are suspected (see Table: Some Causes and Features of Headaches).

Some Causes and Features of Headaches

Type or Cause

Common Features*


Primary headache (not due to another disorder)

A severe, piercing headache that

  • Affects one side of the head and is focused around the eye

  • Lasts 15 to 180 minutes

  • Often occurs at the same time of day

  • Occurs in clusters, separated by periods of time when no headaches occur

  • Is usually not worsened by light, sounds, or odors

  • Is not accompanied by vomiting

Inability to lie down and restlessness (sometimes expressed by pacing)

On the same side as the pain: A runny nose, tearing, drooping of the eyelid, and sometimes swelling of the area below the eye

A doctor's examination

Occasionally MRI or CT of the head to rule out other disorders, particularly if the headaches have developed recently or if the pattern of symptoms has changed

A moderate to severe headache that

  • Is typically pulsating or throbbing, usually on one side but sometimes on both sides of the head

  • Lasts several hours to days

  • May be triggered by lack of sleep, a head injury, hunger, or certain wines and foods

  • May be worsened by physical activity

  • Is lessened with sleep

  • Is often accompanied by nausea, vomiting, and sensitivity to loud sounds, bright light, and/or odors

Often a sensation that a migraine is beginning (called a prodrome), which may include mood changes, loss of appetite, and nausea

Sometimes preceded by temporary disturbances in sensation, balance, muscle coordination, speech, or vision, such as seeing flashing lights and having blind spots (these symptoms are called the aura)

Same as those for cluster headaches

Usually a mild to moderate headache that

  • Feels like tightening of a band around the head, starting at the front of the head or the area around the eyes

  • Spreads over the whole head

  • Lasts 30 minutes to several days

  • May be worse at the end of the day

  • Is not worsened by physical activity, light, sounds, or odors

  • Is not accompanied by nausea, vomiting, or any other symptoms

Same as those for cluster headaches

Secondary headache (due to another disorder)

Light-headedness, loss of appetite, nausea and vomiting, fatigue, weakness, irritability, or difficulty sleeping

In people who have recently gone to a high altitude (including flying 6 hours or more in an airplane)

A doctor's examination

Brain tumor, abscess, or another mass in the brain, such as a hematoma (an accumulation of blood)

A mild to severe headache that

  • May become progressively worse

  • Usually recurs more and more often and eventually becomes constant without relief

  • May result in blurred vision when a person suddenly changes position

  • May be accompanied by clumsiness, weakness, confusion, nausea, vomiting, seizures, or impaired vision


Carbon monoxide exposure (during winter, people may breathe this gas if heating equipment is not adequately vented)

Possibly no awareness of the exposure because carbon monoxide is colorless and odorless

A blood test

Dental infections (in upper teeth)

Pain that is

  • Usually felt over the face and mostly on one side

  • Worse when chewing


Dental examination

Encephalitis (infection of the brain)

Headaches with varying characteristics

Often accompanied by fever, worsening drowsiness, confusion, agitation, weakness, and/or clumsiness

Seizures and coma

MRI or CT and a spinal tap

A throbbing pain felt on one side of the head at the temple

Pain when combing the hair or while chewing

Sometimes enlarged arteries in the temples (temporal arteries) and aches and pains, particularly in the shoulders, thighs, and hips

Possibly impaired vision or loss of vision

More common among people over 55

A blood test to measure the erythrocyte sedimentation rate (ESR), which can detect inflammation

Biopsy of the temporal artery

Imaging such as MRI or magnetic resonance angiography (MRA)

Glaucoma—a type called closed-angle glaucoma—that starts abruptly (acute)

Moderate or severe pain that occurs at the front of the head or in or over an eye

Red eyes, halos seen around lights, nausea, vomiting, and loss of vision

An eye examination as soon as possible

Low-pressure headache (which occurs when cerebrospinal fluid pressure is removed or leaks out)

Intense headaches, often accompanied by a stiff neck and nausea

Pain that worsens when sitting or standing and that is relieved by lying flat

Usually occurs after a spinal tap (lumbar puncture)

A doctor's examination

If the headache develops on its own (not after a spinal tap), MRI with a contrast agent, injected into a vein

Head injury (postconcussion syndrome)

Headache that begins immediately or shortly after a head injury (with or without loss of consciousness)

Sometimes a faulty memory, personality changes, or both


Idiopathic intracranial hypertension (increased pressure within the skull without any evidence of a cause)

Headaches that

  • Occur daily or almost daily, with fluctuating intensity

  • Affect both sides of the head

Sometimes double or blurred vision, nausea, or ringing in the ears that occurs in time with the pulse (pulsatile tinnitus)

MRI and magnetic resonance venography, followed by a spinal tap

Intracerebral hemorrhage (bleeding within the brain)

Mild or severe pain that

  • Begins suddenly

  • Occurs on one or both sides of the head

  • Is accompanied often by nausea and sometimes by vomiting

Possibly severe drowsiness, clumsiness, weakness, difficulty speaking or understanding speech, loss of vision, loss of sensation, or confusion

Occasionally seizures or coma


Medication overuse headache

Chronic and often daily headaches

Often in people who have migraine or tension-type headaches

Overuse of pain relievers (analgesics such as NSAIDs or opioids), barbiturates, caffeine, or sometimes triptans or other drugs to treat headaches

A doctor's examination

A severe, constant headache


Neck stiffness that makes lowering the chin to the chest painful and sometimes impossible

A feeling of illness, drowsiness, nausea, or vomiting

A spinal tap (often preceded by CT)

Pain that

  • Is sometimes felt in the face, at the front of the head, or as tooth pain

  • May begin suddenly and last only days or hours or begin gradually and be persistent

A runny nose, sometimes with pus or blood

A feeling of illness, possibly a cough at night, and often a fever

A doctor's examination

Possibly CT of the sinuses or endoscopy of the nose

Subarachnoid hemorrhage (bleeding between the inner and middle layers of tissues covering the brain)

Severe, constant pain that

  • Begins suddenly and peaks within a few seconds (thunderclap headache)

  • Is often described as the worst headache ever experienced

Possibly brief loss of consciousness as the headache begins

Possibly drowsiness, confusion, difficulty being aroused, or coma

A stiff neck, nausea and vomiting, dizziness, and low back pain


If MRI or CT results are negative, often a spinal tap

Subdural hematoma (a pocket of blood between the outer and middle layers of tissues covering the brain)

Headaches with varying characteristics

Possibly sleepiness, confusion, forgetfulness, and/or weakness or paralysis on one side of the body


Pain when chewing hard foods

Sometimes pain in or around the jaw or in the neck

Sometimes clicking or popping when the mouth is opened, locking of the jaw, or difficulty opening the mouth wide

Physical examination, sometimes by a dentist

Occasionally MRI, x-rays, or CT

*Features include symptoms and results of the doctor's examination. Features mentioned are typical but not always present.

CT = computed tomography; MRI = magnetic resonance imaging; NSAIDs = nonsteroidal anti-inflammatory drugs.


Treatment of headache depends on the cause. If the headache is a tension headache or if it accompanies a minor viral infection, people can take acetaminophen or a nonsteroidal anti-inflammatory drug (NSAID).

Essentials for Older People

If headaches begin after age 50, doctors usually assume they result from another disorder until proved otherwise. Many disorders that cause headaches, such as giant cell arteritis, brain tumors, and subdural hematomas (which may result from falls), are more common among older people.

Treatment of headaches may be limited in older people. They are more likely to have disorders that prevent them from taking some of the drugs used to treat migraines and cluster headaches (triptans and dihydroergotamine—see Table: Drugs Used to Treat Migraines). These disorders include angina, coronary artery disease, and uncontrolled high blood pressure. If older people need to take drugs to treat headaches that can have sedating effects, they must be monitored closely.

Key Points

  • Most headaches do not have a serious cause, particularly if the headaches began at a young age, if they have not changed over time, and if results of the examination are normal.

  • If warning signs are present, people should see a doctor.

  • Most headaches do not require testing.

  • Doctors can usually determine the type or cause of headaches based on the medical history, symptoms, and results of a physical examination.

  • If doctors suspect that the cause is a serious disorder (such as a hemorrhage or an infection), CT or MRI is usually done, often immediately.

  • If doctors suspect meningitis or encephalitis, a spinal tap is done.

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