What Is a Migraine? Symptoms, Causes, and How It Differs From a Conventional Headache

What Migraine Actually Is

Migraine is a neurological disorder, not a headache condition. The headache is one symptom, often the most disabling one, but it is not the whole picture. The International Headache Society classifies migraine as a distinct disorder with its own diagnostic criteria, its own mechanisms, and its own treatment landscape separate from other headache types.

The disorder affects the trigeminal nerve system and involves waves of electrical activity across the brain called cortical spreading depression. These waves trigger a cascade of events. Blood vessels dilate, inflammatory substances are released, and pain signals travel through pathways that a standard headache does not activate. This is why migraine pain is often described as pulsating or throbbing. That quality reflects vascular involvement rather than the dull pressure of a tension headache.

How It Differs From a Conventional Headache

The distinction matters clinically. A tension headache typically produces bilateral pressure, a squeezing sensation around the head, and mild to moderate pain that does not worsen with physical activity. It does not usually cause nausea, vomiting, or extreme sensitivity to light and sound.

Migraine typically produces moderate to severe pain, often on one side of the head, that worsens with routine activity. It is accompanied by nausea in the majority of cases. Sensitivity to light and sound can make normal environments intolerable. Many people with migraine need to lie down in a dark, quiet room for hours or days. That is not a tension headache.

Core Symptoms

The symptoms of migraine extend well beyond head pain. During an attack, people commonly experience throbbing or pulsating head pain, typically unilateral but sometimes bilateral. Nausea and in some cases vomiting are common. Photophobia, sensitivity to light, can make ordinary indoor lighting feel painful. Phonophobia, sensitivity to sound, makes conversation or ambient noise difficult to tolerate. Osmophobia, sensitivity to smells, is less commonly discussed but frequently reported. Cognitive impairment during attacks, sometimes called migraine fog, affects concentration, word retrieval, and processing speed.

In attacks that involve aura, neurological symptoms precede or accompany the headache phase. These typically include visual disturbances such as zigzag lines, blind spots, or flickering lights. Less commonly, people experience sensory changes, speech difficulties, or motor symptoms.

What Causes Migraine

Migraine has a strong genetic component. First-degree relatives of people with migraine are two to four times more likely to develop the condition themselves, according to research published in the journal Neurology. But genetics creates the susceptibility. Triggers initiate the attack.

The underlying mechanism involves the trigeminal vascular system and a neuropeptide called calcitonin gene-related peptide (CGRP), which plays a central role in transmitting pain signals during attacks. Elevated CGRP levels during migraine attacks have been documented consistently in research. The most recent class of migraine specific medications, CGRP antagonists and anti-CGRP monoclonal antibodies, work by blocking this pathway.

Environmental and physiological triggers interact with this underlying sensitivity to initiate attacks in susceptible individuals. Hormonal changes, sleep disruption, barometric pressure shifts, certain foods, stress, and dehydration are among the most commonly documented.

Who Gets Migraine

Migraine affects approximately one in seven people worldwide, according to the World Health Organization. It is the second leading cause of disability globally. Women are affected three times more often than men, largely due to the influence of estrogen on migraine mechanisms. The condition most commonly begins in adolescence or early adulthood and tends to peak in the thirties and forties.

Despite its prevalence, migraine remains underdiagnosed and undertreated. Research from the American Migraine Foundation suggests that fewer than half of people with migraine have ever received a formal diagnosis.

Why Tracking Matters

Because migraine is episodic and driven by individual trigger patterns, understanding one's own condition requires data. What triggers one person's attacks may have no effect on another. Keeping a detailed migraine diary, logging attack timing, duration, severity, potential triggers, and medication response, is consistently recommended by neurologists as the foundation of effective migraine management. The American Headache Society and the National Headache Foundation both include diary keeping in their patient guidance.

The information a well-kept diary generates is also what makes a neurologist appointment productive. A patient who arrives with weeks of structured data gives their provider something to work with. One who arrives without it leaves the appointment guessing.