Headaches are a common health problem — most people experience them at some time.

Factors that lead to headaches may be:

emotional, such as stress, depression, or anxiety
medical, such as migraine or high blood pressure
physical, such as an injury
environmental, such as the weather
Frequent or severe headaches can affect a person’s quality of life. Knowing how to recognize the cause of a headache can help a person take appropriate action.

Causes

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A broad range of conditions and factors can cause headaches.
A headache can affect any part of the head, and pain may be present in one or several locations.

Headaches can cause various types of pain, and classifying the pain can help a doctor reach a diagnosis.

Doctors also categorize headaches based on whether an underlying health condition is responsible for the pain. In other words, a headache may be primary or secondary, the International Headache Society note.

Primary headaches

A primary headache is not a symptom of an underlying illness. Instead, these headaches result from problems involving the structures of the head and neck.

A primary headache may be due to overactivity of:

specific areas of the brain
blood vessels
muscles
nerves
brain chemicals
Common types of primary headaches include cluster and tension headaches.

Also, headaches can result from using medication for the pain too often. In this case, a person has a medication overuse headache, and this is another type of primary headache.

Secondary headaches

These are symptoms of underlying medical conditions. The cause of a secondary headache may be:

pregnancy
systemic conditions, such as an infection
hypothyroidism
giant cell arteritis
a stroke
a brain tumor
Secondary headaches can result from serious health issues. It is important to seek medical advice if any headache:

is severe or disruptive
is persistent
occurs regularly
does not improve with medication
occurs alongside other symptoms, such as confusion, a fever, sensory changes, or stiffness in the neck
What is causing this headache on the left side?

Types
Some of the various kinds of headache include:

Tension-type headache

This is a common form of primary headache. The pain usually arises gradually, in the middle of the day.

A person may feel:

as if they have a tight band around their head
a constant, dull ache on both sides of the head
pain spreading to or from the neck
Tension-type headaches may be:

Episodic: These attacks usually last for a few hours, though they can last for several days.

Chronic: This involves tension-type headaches occurring on 15 or more days per month for at least 3 months.

Learn more about tension-type headaches.

Migraine

A migraine headache may involve pulsating, throbbing pain. It often occurs on one side of the head but may switch sides.

During an episode, a person may also experience:

lightheadedness
sensory disturbances, such as changes in vision, known as an aura
sensitivity to light or sound
nausea, possibly with vomiting
Migraine headaches are the second most common form of primary headache. They can significantly impact the quality of life.

A migraine episode may last from a few hours to 2–3 days. The frequency of episodes can vary greatly; they may occur from once a week to once a year.

Learn more about migraine.

Medication overuse headache

This was once known as a rebound headache. It occurs if a person uses medication to treat headaches too often.

Medication overuse headaches tend to result from taking opiate-based medications, such as those that contain codeine or morphine.

Beyond the headache, a person may experience:

neck pain
restlessness
a feeling of nasal congestion
reduced sleep quality
Symptoms can vary, and the pain may change from day to day.

According to The Migraine Trust, a charity organization based in the United Kingdom, people with migraine often develop medication overuse headaches. These can cause migraine episodes to occur more frequently and become more severe.

Cluster headache

These headaches usually last between 15 minutes and 3 hours, and they may occur one to eight times per day.

Cluster headaches may arise frequently for 4–12 weeks, then disappear. They tend to happen at around the same time each day.

Between the clusters, the person may have no symptoms. These remission periods may last months or years.

Cluster headaches often involve:

brief but severe pain
pain around one eye
tearing or redness in the eye
a drooping eyelid
a blocked or runny nose
a smaller pupil in one eye
facial sweating
Find out more about cluster headaches.

Thunderclap headache

These are sudden, severe headaches that people often describe as the “worst headache of my life.” They reach maximum intensity in under 1 minute and last longer than 5 minutes.

A thunderclap headache is a secondary headache that can indicate a life-threatening condition, such as:

an aneurysm
reversible cerebral vasoconstriction syndrome
meningitis
pituitary apoplexy
bleeding in the brain
a blood clot in the brain
People who experience these sudden, severe headaches should receive immediate medical care.