Merck Manual

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Some Causes and Features of Headaches

Some Causes and Features of Headaches

Type or Cause

Common Features*

Diagnostic Approach†

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 30 to 180 minutes (usually 30 minutes to 1 hour)

  • 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)

A doctor's examination alone

Occasionally MRI 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 alone

Blood clots in a large vein that drains blood from the brain (cerebral venous sinus thrombosis)

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)

Sometimes seizures and symptoms similar to those of a stroke (such as paralysis of an arm or leg and loss of vision)

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

  • Is worsened by lying down and is worse when the person awakens in the morning or it awakens the person from sleep

MRI or, if MRI is unavailable or contraindicated, CT

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

Headaches with varying characteristics

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

Seizures and coma

MRI or, if MRI is unavailable or contraindicated, CT

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 tender, 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

Sometimes fatigue, fever, and weight loss

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

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

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

Sometimes a faulty memory, personality changes, or both

Sometimes a doctor's examination alone

Usually CT or MRI

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

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

MRI or, if MRI is unavailable or contraindicated, CT

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)

Sometimes a doctor's examination alone

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

Chronic and often daily headaches that vary in location and intensity

Often present when the person awakens in the morning

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 alone

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 (usually 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 alone

Sometimes CT of the sinuses or endoscopy of the nose

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 and nausea and vomiting


If MRI or CT results are negative, a spinal tap

Headaches with varying characteristics

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

More common among older people and people who have dementia or who take anticoagulants§ or abuse alcohol


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

Trigeminal neuralgia

Repeated short, lightning-like bursts of pain in the middle and lower half of one side of the face

A doctor's examination alone

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

† Although a doctor's examination is always done, it is mentioned in this column only if the diagnosis can sometimes be made by the doctor's examination alone, without any testing.

‡ Cerebrospinal fluid is the fluid that surrounds the brain and spinal cord and helps cushion and support them.

§ Anticoagulants are drugs that prevent blood from clotting or slow the clotting process.

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