Migraine is diagnosed almost entirely through your medical history and a description of your symptoms. There is no blood test, brain scan, or biomarker that confirms it. Instead, doctors match your pattern of attacks against a well-established set of criteria, rule out other causes, and arrive at a diagnosis based on what you report. That makes the information you bring to your appointment one of the most important tools in the process.
The Core Criteria for Migraine Without Aura
The standard used worldwide comes from the International Classification of Headache Disorders. To qualify for a diagnosis of migraine without aura, you need to have experienced at least five attacks that meet a specific pattern. Each attack lasts between 4 and 72 hours if untreated, and the headache itself has at least two of the following features: pain on one side of the head, a pulsating or throbbing quality, moderate to severe intensity, or pain that gets worse with ordinary physical activity like walking or climbing stairs.
On top of the headache characteristics, you also need at least one accompanying symptom during the attack: either nausea or vomiting, or sensitivity to both light and sound. The five-attack minimum exists because a single bad headache can have many causes. The pattern over multiple episodes is what points toward migraine specifically.
How Migraine With Aura Is Identified
About a quarter to a third of people with migraine experience aura, a set of reversible neurological symptoms that typically appear before the headache begins. The threshold here is lower: only two attacks with aura are needed for diagnosis.
Visual aura is by far the most common type. It often shows up as a zigzag line or shimmering arc near the center of your vision that gradually expands outward, sometimes leaving a temporary blind spot in its wake. Sensory aura is the next most frequent, usually a slow-moving wave of tingling or pins and needles that spreads across one side of the body, face, or tongue. Numbness can follow, or appear on its own. Less commonly, aura affects speech, causing difficulty finding words or speaking clearly.
A key feature that separates aura from something more alarming is the way it behaves. Aura symptoms build gradually over at least five minutes, each one typically lasts between 5 and 60 minutes, and they resolve completely. If multiple aura symptoms occur, they usually happen in sequence rather than all at once. The headache follows the aura within an hour, though in some cases aura can occur without any headache at all.
What Your Doctor Does During the Visit
Because migraine doesn’t show up on any scan, the physical examination serves a different purpose: ruling out other conditions. Your doctor will check vital signs including blood pressure, temperature, and pulse. A focused neurological exam follows, covering mental status, cranial nerve function (including looking at the back of your eyes for optic nerve swelling), strength and sensation in your limbs, reflexes, coordination, and how you walk. A neck exam checks for signs of meningeal irritation, which could indicate infection or bleeding. Sometimes the jaw and surrounding muscles are examined to rule out temporomandibular joint problems as a headache source.
If everything in this exam is normal and your headache history fits the migraine pattern, that’s typically enough for a diagnosis. The exam itself is brief, but it’s doing important work behind the scenes.
When Brain Scans Are Needed
The American College of Radiology specifically recommends against imaging for primary headaches like migraine when there are no warning signs and the neurological exam is normal. An MRI or CT scan won’t confirm migraine, and routine scanning in straightforward cases adds cost without changing the diagnosis.
Imaging becomes appropriate when red flags are present. The criteria that typically trigger a scan include headaches that are increasing in frequency or severity, headaches accompanied by fever or a new neurological symptom, a history of cancer or a weakened immune system, new-onset headaches after age 50, or headaches that started after head trauma. When any of these apply, a CT scan or MRI of the head helps rule out secondary causes like bleeding, tumors, or structural abnormalities.
Red Flags That Point Away From Migraine
Doctors use a mental checklist sometimes abbreviated as SNOOP to identify headaches that may have a dangerous underlying cause rather than being primary migraine.
- Systemic symptoms or illness: Fever, night sweats, unexplained weight loss, or an immune-compromising condition.
- Neurological symptoms: New weakness in an arm or leg, unusual numbness, or visual changes that don’t fit the typical aura pattern described above.
- Onset that is sudden: A headache that hits maximum intensity within seconds, sometimes called a thunderclap headache, can signal a vascular emergency like a ruptured aneurysm and needs immediate evaluation.
- Older age at onset: A first-ever headache disorder appearing after age 50 is more likely to have a secondary cause.
- Progression: Headaches that are clearly and steadily getting worse over weeks or months, rather than coming and going in a stable pattern.
- Positional changes: Pain that dramatically shifts in intensity when you stand up, lie down, cough, or strain.
- Pregnancy: New headaches during or shortly after pregnancy warrant evaluation for vascular or hormonal complications.
None of these red flags automatically mean something serious is wrong, but each one changes the diagnostic approach and usually leads to additional testing.
Chronic Versus Episodic Migraine
Migraine is classified as chronic when you have headaches on 15 or more days per month for more than three months, with at least 8 of those days having migraine features. Everything below that threshold is considered episodic migraine. This distinction matters because it affects which treatments are most appropriate and whether you may qualify for certain preventive therapies. The shift from episodic to chronic often happens gradually, which is one reason tracking your headaches over time is valuable.
Vestibular Migraine
Some people experience migraine primarily as episodes of vertigo or dizziness rather than head pain. Vestibular migraine requires at least five episodes of moderate to severe vestibular symptoms lasting anywhere from 5 minutes to 72 hours. These symptoms include a false sensation of spinning (either feeling like you’re moving or like the room is moving), dizziness triggered by head motion, and vertigo brought on by complex visual environments like scrolling screens or busy traffic.
The duration of vestibular migraine episodes varies enormously. Roughly a third of people have episodes lasting minutes, a third experience hours-long attacks, and another third deal with symptoms over several days. Because vertigo has many potential causes, diagnosis requires that at least half of the episodes occur alongside typical migraine features like one-sided headache, light sensitivity, sound sensitivity, or visual aura.
How Children Are Diagnosed Differently
Migraine in children and teenagers uses the same general framework, with a few important modifications. The minimum attack duration drops to 2 hours instead of 4, reflecting the fact that pediatric migraine attacks tend to be shorter. If a child falls asleep during an attack, the time spent sleeping counts toward the total duration.
Location requirements are also more flexible. While adult migraine is characteristically one-sided, children commonly experience pain on both sides of the head, and bilateral headaches still qualify. Light and sound sensitivity can be harder to assess in younger children, so doctors are allowed to infer these from behavior, like a child hiding under blankets, retreating to a dark room, or asking people to be quiet.
How a Headache Diary Helps
The single most useful thing you can do before a diagnostic appointment is track your headaches for at least a few weeks. A good headache diary records the date and duration of each attack, pain severity on a simple 1 to 3 scale (mild, moderate, severe), any treatments you tried and whether they helped, and brief notes about accompanying symptoms or possible triggers.
This kind of record gives your doctor the raw data needed to count attack frequency, confirm the duration pattern, and identify whether your headaches meet migraine criteria. It also reveals whether your headaches are progressing, which is relevant to the red flag assessment. Many people underestimate or overestimate their headache frequency when asked to recall it from memory. A diary removes that guesswork and often speeds up the diagnostic process significantly. Free printable versions are available from organizations like the VA and the American Migraine Foundation, and numerous smartphone apps serve the same purpose.