Classification of Headache & Migraine

Headache disorders are classified internationally using the International Classification of Headache Disorders, Third Edition (ICHD-3), produced by the International Headache Society. This provides recognised diagnostic criteria and a common clinical language for distinguishing different headache patterns.

The first and most important distinction is whether the headache is:

  • A primary headache disorder, representing a condition in its own right; or
  • A secondary headache, occurring because of another underlying disorder, illness, injury or medication-related factor.

Classification is based on the pattern and duration of symptoms, associated features, clinical examination and, where necessary, further investigation. A patient may also experience more than one headache disorder at the same time.

Headaches and migraines are classified by the International Headache Society (ICHD-3) as either primary or secondary headaches (ICHD-3.org).

Primary Headache Disorders

In a primary headache disorder, the headache itself is the condition rather than a symptom caused by another disease. The principal categories include:

  • Migraine
  • Tension-type headache
  • Trigeminal autonomic cephalalgias, including cluster headache
  • Other primary headache disorders, such as primary stabbing, cough, exertional or sexual-activity headache

Primary headaches can still be severe and disabling despite the absence of another underlying disease.

Secondary Headaches

A secondary headache occurs because of another condition or identifiable factor. Potential causes include:

  • Head or neck injury
  • Vascular disorders
  • Infection or systemic illness
  • Disorders affecting pressure within the skull
  • Medication use, medication withdrawal or medication overuse
  • Disorders of the eyes, ears, sinuses, teeth or jaw
  • Cervical musculoskeletal dysfunction
  • Significant metabolic or physiological disturbance

Most headaches encountered in clinical practice are primary, but recognising features that suggest a secondary cause is an essential part of assessment.

Common Primary Headache Disorders

Migraine

Migraine commonly produces recurrent attacks lasting several hours or longer. Pain may be one-sided or bilateral and is often accompanied by nausea, sensitivity to light or sound, and worsening with routine physical activity. Some patients experience aura or other neurological symptoms.

Tension-Type Headache

Tension-type headache is usually described as pressing or tightening rather than pulsating. It is commonly bilateral, mild to moderate in intensity and not typically aggravated by ordinary physical activity. Neck and scalp muscular sensitivity may coexist.

Cluster Headache and Related Disorders

Cluster headache belongs to the group known as trigeminal autonomic cephalalgias. It causes severe, usually strictly one-sided pain around the eye or temple, accompanied by features such as tearing, nasal symptoms, eyelid change or marked restlessness. Prompt recognition is important because management differs substantially from migraine.

Other Primary Headache Disorders

Less common primary headaches may be associated with coughing, exertion, sexual activity, cold stimuli or brief stabbing pains. A first presentation may require investigation before it can safely be classified as a primary disorder.

Why Headache and Neck Pain Often Overlap

Sensory information from the head and upper cervical spine converges within the trigeminocervical system. This neurological overlap helps explain why migraine and other headache disorders may produce pain in the forehead, temple, eye, face, occiput or upper neck.

Neck pain may:

  • Form part of the migraine attack itself
  • Occur because of muscular guarding or altered movement
  • Act as a contributing factor in some patients
  • Represent a separate cervical or musculoskeletal disorder

The presence of neck pain does not automatically mean that the headache originates from the neck. Clinical assessment is needed to distinguish migraine-associated neck symptoms from cervicogenic headache and other causes.

Why Headache Classification Can Be Complex

The ICHD-3 contains an extensive range of headache diagnoses and subtypes. Classification depends on details such as:

  • Age at onset
  • Frequency and duration of attacks
  • Location and character of pain
  • Associated neurological or sensory symptoms
  • Aggravating and relieving factors
  • Medication use and treatment response
  • Whether the pattern has changed over time
  • Findings from examination or investigation

Symptoms do not always fit neatly into one category. Migraine and tension-type headache may coexist, while frequent use of acute medication can introduce medication-overuse headache. A previously episodic disorder may also become chronic.

A carefully maintained headache diary can be valuable for recording attack frequency, associated symptoms, medication use, hormonal timing and possible triggers. This often makes the underlying pattern clearer and supports more accurate diagnosis.

Classification of Headache & Migraine

Features That May Suggest a Secondary Headache

Certain features increase the need to consider an underlying cause and may require medical investigation. These include:

  • A sudden, extremely severe or “thunderclap” headache
  • A new headache accompanied by weakness, altered sensation, speech difficulty, confusion, seizure or loss of consciousness
  • A significant change in a longstanding headache pattern
  • Progressive worsening over days or weeks
  • Headache associated with fever, systemic illness, unexplained weight loss or a stiff neck
  • New headache after a head or neck injury
  • New-onset headache after the age of 50
  • Headache during pregnancy or the postnatal period
  • Headache in someone with cancer or significant immune suppression
  • Headache consistently triggered by coughing, straining, exertion or a change in posture
  • Persistent visual disturbance, scalp tenderness or jaw pain when eating

These features do not necessarily indicate serious disease, but they should not be ignored. A sudden extremely painful headache, or headache accompanied by an acute neurological deficit, seizure, confusion or loss of vision, requires immediate medical attention through 999 or A&E.

Why Accurate Classification Matters

Correct classification guides both investigation and treatment. A medicine that is appropriate for migraine may be ineffective for cluster headache, while suspected secondary headache may require urgent imaging, blood tests or specialist referral rather than symptomatic treatment alone.

Classification also helps to:

  • Avoid unnecessary or repeated investigations
  • Identify medication-overuse headache
  • Select appropriate acute and preventive treatments
  • Recognise when osteopathic or other supportive care may be relevant
  • Monitor whether the headache pattern is improving, worsening or changing
  • Communicate clearly with GPs, neurologists and other clinicians

At The Health Equation, the diagnosis is considered alongside the patient’s broader clinical presentation rather than in isolation.

Continue Exploring Headache and Migraine

Our supporting pages provide further information about headache and migraine:

Book a Diagnostic Consultation

Patients seeking assessment for recurrent, persistent or changing headache symptoms should book a 60-minute Diagnostic Consultation with Gerry Gajadharsingh DO.

The consultation provides time to review the complete symptom history, previous diagnoses and treatment responses; undertake an appropriate examination; and determine whether further investigation or specialist referral may be required.

Patients are encouraged to send relevant medical correspondence, imaging reports and blood-test results before attending. A comprehensive written report is included.