Use this calculator to check whether a patient’s headache pattern fits migraine without aura, migraine with aura, chronic migraine, or possible medication-overuse headache. It works best when you enter a clear headache history, including attack number, duration, symptom pattern, monthly frequency, aura features, and acute medicine use.sign-155-migraine-2026-update-002.pdf

Step 1: Check for red flags first

Start by answering the red flag question. If the patient has thunderclap onset, focal neurological signs, fever, neck stiffness, head injury, pregnancy/postpartum onset, or progressive worsening, the calculator should not be used to reassure or delay review.sign-155-migraine-2026-update-002.pdf

Step 2: Enter attack details

Add the number of migraine-like attacks, the usual attack duration, and whether the headaches are unilateral, pulsating, moderate to severe, or worsened by routine activity. For migraine without aura, the pattern usually needs at least five attacks lasting 4 to 72 hours, with at least two headache features and at least one associated symptom group.sign-155-migraine-2026-update-002.pdf

Step 3: Add associated symptoms

Tick nausea or vomiting if present, and tick photophobia and phonophobia if these occur together. These symptoms are part of the core diagnostic pattern for migraine without aura.sign-155-migraine-2026-update-002.pdf

Step 4: Record aura features

If the patient has aura, enter the number of aura attacks and the number of aura symptom types, then tick the aura features that apply. Migraine with aura usually needs at least two attacks, one or more fully reversible aura symptoms, and at least two supportive aura characteristics such as gradual spread, 5 to 60 minute duration, unilateral symptoms, or headache within 60 minutes.sign-155-migraine-2026-update-002.pdf

Step 5: Check monthly frequency

Enter headache days per month and migraine-feature days per month. If headache occurs on 15 or more days per month for more than 3 months, with migraine features on at least 8 days per month, the calculator should flag chronic migraine.sign-155-migraine-2026-update-002.pdf

Step 6: Review medicine use

Record the number of days per month the patient uses triptans, opioids, combination analgesics, or simple analgesics. The calculator should flag possible medication-overuse headache if use is above guideline thresholds, especially 10 or more days per month for triptans, opioids, or combination analgesics, or 15 or more days per month for simple analgesics.sign-155-migraine-2026-update-002.pdf

Step 7: Read the result

The calculator will show one of four main outputs: migraine without aura, migraine with aura, chronic migraine, or possible medication-overuse headache. If the result is negative, it does not rule out migraine completely; it may mean the history is incomplete, the pattern is atypical, or another headache disorder should be considered.sign-155-migraine-2026-update-002.pdf

Practical tips

• Use a headache diary if the history is unclear.sign-155-migraine-2026-update-002.pdf

• Enter untreated or unsuccessfully treated attack duration, not just the time the patient “remembered” having pain.sign-155-migraine-2026-update-002.pdf

• If medication overuse is present, address this before escalating long-term treatment where appropriate.sign-155-migraine-2026-update-002.pdf

• Use the calculator as a screening and documentation tool, not as a substitute for clinical judgement.sign-155-migraine-2026-update-002.pdf

Short patient-facing explanation

“This calculator helps check whether your headache pattern matches migraine criteria. It also looks for red flags and medication overuse, which can affect treatment choices.”

A study by SIGN stated that acute migraine should be assessed with a careful history, and that patients should be warned about medication-overuse headache when acute treatment is started.