Migraine

Clinical Snapshot

Migraine is a primary headache disorder — the headache itself is the disease, not a symptom of something else — causing recurrent attacks of moderate-to-severe, often unilateral, pulsating head pain lasting 4-72 hours if untreated, typically accompanied by nausea and/or vomiting and sensitivity to light and sound.^[1] About a quarter to a third of people with migraine experience a fully reversible neurologic aura — usually visual — before or alongside the headache. Migraine is classified as episodic (fewer than 15 headache days a month) or chronic (15 or more headache days a month, with features of migraine on at least 8 of those days, for more than 3 months).^[2] Diagnosis is clinical, based on the ICHD-3 criteria and a normal neurologic examination — routine neuroimaging is not indicated in a patient who meets migraine criteria and has no red flags for a secondary headache disorder.^[3]

Recognize the Condition

ICHD-3 diagnostic criteria (adults)

Migraine without aura

At least 5 attacks; headache lasting 4-72 hours (untreated or unsuccessfully treated); at least 2 of: unilateral location, pulsating quality, moderate-to-severe intensity, aggravation by (or causing avoidance of) routine physical activity; and at least 1 of: nausea and/or vomiting, or both photophobia and phonophobia.

Migraine with aura

Fully reversible aura symptoms — visual (most common), sensory, speech/language, motor, brainstem, or retinal — that develop gradually over at least 5 minutes, with each individual symptom lasting 5-60 minutes; headache typically follows the aura within 60 minutes, though it can accompany or precede it, or occur without any headache at all.

The 4 phases of an attack

Prodrome — hours to 1-2 days before the headache: mood change, fatigue, food cravings, neck stiffness, yawning. Recognizing it is the single most useful skill for treating an attack early.
Aura — present in roughly a quarter to a third of patients; most often visual (zigzag lines, scintillating scotoma, expanding blind spot).
Headache — the attack itself, as defined above.
Postdrome — the "migraine hangover": fatigue, difficulty concentrating, mood change, sometimes lasting a day or more after the headache resolves.

Menstrual migraine

Attacks occurring on day −2 to +3 of menses in at least 2 of 3 cycles, related to the perimenstrual estrogen drop — relevant to both acute-treatment timing and preventive strategy (see Special Populations).

Risk Factors

Family history of migraine — the single strongest risk factor; migraine has a substantial genetic component.
Female sex — migraine is roughly 3 times more common in women than men, largely hormonally mediated.
Age — onset is most common before age 40, with peak prevalence between 25 and 55.
Hormonal fluctuation — the perimenstrual estrogen drop, pregnancy, perimenopause, and combined hormonal contraceptive/hormone therapy use can all influence attack frequency.
Obesity.
Frequent use of acute headache medication itself — a key modifiable risk factor for progression from episodic to chronic migraine (medication overuse headache).
Comorbid depression, anxiety, and other chronic pain conditions — migraine and mood disorders have a bidirectional relationship.
Individual attack triggers — commonly stress (including post-stress "let-down"), disrupted or insufficient sleep, skipped meals or fasting, dehydration, alcohol, specific foods, weather/barometric pressure change, and strong sensory stimuli (bright or flickering light, strong odours). Triggers are highly individual; a headache diary is more useful than a generic avoidance list.

Red Flags & Refer

Any new or changed headache pattern needs a deliberate check for red flags before it is managed as routine migraine. A widely used mnemonic organizes them as SNOOP:

S — Systemic symptoms or signs (fever, meningismus, unexplained weight loss) or a systemic risk factor (known malignancy, immunosuppression, pregnancy).
N — Neurologic signs or symptoms that are new, focal, or unexplained (weakness, sensory loss, ataxia, altered consciousness, papilloedema) — the CHS/Choosing Wisely Canada statement specifically names papilloedema and unexplained focal neurologic signs.^[3]
O — Onset that is sudden or "thunderclap" (reaching maximum intensity within seconds to a minute) — treat as suspected subarachnoid hemorrhage until proven otherwise.
O — Older age at onset — new headache after age 50 is a specifically named red flag in the CHS Choosing Wisely Canada statement.^[3]
P — Pattern change or Progressive course — a clear change from the patient's usual headache pattern, a headache that is positional, or one precipitated by Valsalva, cough, exertion, or sexual activity ("unusual headache attack precipitants").^[3]

Any of these findings means urgent neuroimaging and/or emergency assessment — not routine acute or preventive migraine management.

Assessment & Diagnosis

History

Characterize attack frequency, duration, and quality against the ICHD-3 criteria above, and distinguish headache days from migraine days per month — this distinction drives both the chronic-migraine definition and the preventive-therapy threshold decision.
Ask specifically and quantitatively about acute medication use frequency (days per month, by class) at every assessment — this is the single most important, most commonly missed history item, since it identifies evolving medication overuse headache before it derails treatment.
Screen for red flags (above), prior neuroimaging, prior preventive trials and why they were stopped, and menstrual-cycle relationship in patients who menstruate.
A headache diary or tracking app (e.g., the Canadian Migraine Tracker app) meaningfully improves the quality of this history over recall alone.^[4]

Examination

A normal general and neurologic examination is expected in migraine and should be documented; any abnormal finding is itself a red flag requiring further workup rather than a migraine diagnosis by default.

Investigations

No laboratory testing or neuroimaging is routinely required to diagnose migraine in a patient who meets ICHD-3 criteria, has a normal examination, and has no red flags — the yield of imaging in this population is very low, and incidental findings can generate unnecessary anxiety and further testing.^[3]

Episodic vs. chronic migraine

Chronic migraine is defined as 15 or more headache days a month, with features of migraine (or response to migraine-specific treatment) on at least 8 of those days, for more than 3 months. This distinction matters directly for treatment: chronic migraine is the specific indication for onabotulinumtoxinA and receives its own graded recommendations in the updated CHS prevention guideline.^[2]

Treatment Targets

Rapid, complete, and consistent relief of individual attacks, with minimal recurrence, using the fewest doses needed.
Restore normal function during an attack rather than merely blunting pain.
Keep acute-medication use below the frequency that risks medication overuse headache.
For patients who qualify, reduce attack frequency, severity, and duration through preventive therapy, and reduce migraine-related disability and lost function.
Identify and treat comorbid depression, anxiety, and sleep disruption, which both worsen migraine burden and are worsened by it.

Choose Initial Treatment

Direct treatment rule — acute attack

Stratified care, not forced step therapy

Match the initial acute agent to attack severity and disability, rather than forcing every patient through NSAIDs first — a patient with reliably severe, disabling attacks should start with a triptan.^[1]

Mild-moderate, non-disabling attacks an NSAID (naproxen, ibuprofen, diclofenac potassium, or ASA) or acetaminophen, taken as early in the attack as possible — efficacy drops sharply the longer treatment is delayed.^[5]

Moderate-severe attacks, significantly disabling attacks, or NSAID/acetaminophen failure a triptan — choose the formulation to match the attack: a fast-progressing attack or prominent nausea favours a nasal spray or subcutaneous injection (sumatriptan) or an orally-dissolving tablet (rizatriptan, zolmitriptan) over a swallowed tablet; frequent recurrence favours a longer-half-life agent (frovatriptan, naratriptan).^[4]

Suboptimal response to a triptan or NSAID alone a fixed combination of sumatriptan/naproxen, or triptan plus a separately-dosed NSAID, is a reasonable next step before abandoning either class.

Triptan-contraindicated (cardiovascular disease, uncontrolled hypertension, hemiplegic or brainstem-aura migraine) or triptan-non-responsive after an adequate trial a gepant — rimegepant or ubrogepant. Gepants are not vasoconstrictive, so cardiovascular disease is not a contraindication and cardiovascular risk factors are not a precaution — this is their principal clinical niche.^[1]

Add an antiemetic (metoclopramide or prochlorperazine — both also carry some independent anti-migraine effect — or dimenhydrinate/ondansetron) for nausea or vomiting at any severity tier, and whenever oral absorption is a concern.

Do not use as first-line acute therapy

Opioid analgesics and combination analgesics containing opioids or barbiturates (e.g., butalbital-containing products) — NSAIDs and triptans are the recommended first-line acute agents; opioids increase pain sensitization and materially raise the risk of progression to chronic daily headache.^[3]

Triptans or dihydroergotamine in hemiplegic migraine, migraine with brainstem aura, or significant uncontrolled cardiovascular disease.

Medication-overuse headache — cap acute treatment days

Keep triptans, gepants, ergotamines, opioids, and combination analgesics to fewer than 10 treatment days a month, and NSAIDs or acetaminophen to fewer than 15 treatment days a month — exceeding either threshold risks medication overuse headache and progression to chronic daily headache.^[3]

Direct treatment rule — preventive therapy

When to start

Offer preventive therapy for 4 or more monthly moderate-or-severe headache days that are not responding adequately to acute medication, or for 8 or more monthly headache days even when acute medication is working well, or for significant migraine-related disability/quality-of-life impact despite optimized acute treatment.^[2]

First-line options

Episodic migraine, oral first-line propranolol, candesartan, or amitriptyline all carry strong or upgraded recommendations in the updated CHS guideline; topiramate remains an option but was downgraded to a weak recommendation for episodic migraine in the 2024 update.^[2]

CGRP monoclonal antibodies erenumab, fremanezumab, galcanezumab, and eptinezumab all carry strong recommendations across both episodic and chronic migraine, and can be considered first-line for high-frequency episodic migraine with significant disability — though Canadian public and most private drug plans still require documented inadequate response, intolerance, or contraindication to 2 or more conventional oral preventives first, an access-driven rather than efficacy-driven sequencing.^[2]

Chronic migraine specifically onabotulinumtoxinA (PREEMPT injection protocol) is a chronic-migraine-specific preventive option, used alone or combined with a CGRP monoclonal antibody.^[2]

Titrate any oral preventive slowly and give it an adequate trial — the target or maximally tolerated dose, sustained for at least 8-12 weeks — before judging it to have failed.

Non-Pharmacologic Treatment

Regular sleep, regular meals (avoid skipping meals/prolonged fasting), and adequate hydration — inconsistency in these basics is one of the most common, most modifiable attack triggers.
Regular aerobic exercise has independent preventive benefit.
Identify individual triggers with a headache diary rather than broad, anxiety-generating avoidance of common but non-universal triggers (foods, weather, etc.) — over-restriction has not been shown to help and can itself add disability.
Stress management, relaxation training, cognitive behavioural therapy, and biofeedback are well-supported behavioural treatments and should be considered alongside — not instead of — pharmacotherapy.^[3]
Neuromodulation devices — external trigeminal nerve stimulation (Cefaly) and non-invasive vagus nerve stimulation (gammaCore) — are available in Canada as an adjunct; they are safe and effective but generally not covered by insurance.^[4]
For patients with typical migraine, a normal exam, and no red flags who are anxious about a serious underlying cause, clear explanation of the diagnosis and reassurance is often more helpful than ordering imaging "just in case."^[3]

Pharmacologic Treatment Options

Drug / intervention	Role	Dose / use	Important adverse effects	Teaching points
Acetaminophen Preferred	Mild-moderate attack, 1st line	1000 mg PO; max 4000 mg/day	Hepatotoxicity at high cumulative dose	Take as early in the attack as possible. Cap use at under 15 days/month.
Naproxen Preferred	Mild-moderate attack, 1st line	500-550 mg PO, may repeat once; max 1100 mg/day	GI upset, dyspepsia; GI bleed risk with chronic use	NSAID of choice for combination with a triptan (see Suvexx).
Ibuprofen Preferred	Mild-moderate attack, 1st line	400 mg PO q4h; max 2400 mg/day	GI upset, dyspepsia	Cap NSAID use at under 15 days/month.
Diclofenac potassium powder Preferred	Mild-moderate attack, faster absorption than tablet	50 mg PO; max 150 mg/day	GI upset, dyspepsia	Dissolvable-powder formulation for faster onset when nausea has not yet set in.
Sumatriptan Preferred	Moderate-severe attack, 1st-line triptan	50-100 mg PO (max 2 doses/24h), or 20 mg intranasal, or 6 mg SC; monthly cap 10 dosing days	Chest/neck tightness, paresthesia, fatigue	SC or nasal spray preferred if nausea/vomiting limits oral absorption or attack escalates quickly.
Rizatriptan Preferred	Moderate-severe attack, triptan alternative	5-10 mg PO or ODT (max 2 doses/24h); monthly cap 10 dosing days	Chest/neck tightness, paresthesia, fatigue	Orally-dissolving tablet does not require water — useful when nausea limits swallowing tablets.
Sumatriptan/naproxen Alternative	Suboptimal response to a triptan or NSAID alone	85 mg/500 mg PO tablet; max 2 tablets/day	Combines the adverse effects of both components	A reasonable next step before abandoning triptan or NSAID monotherapy.
Rimegepant Alternative	Triptan-contraindicated or triptan-non-responsive	75 mg PO orally-dissolving tablet; once per 24h only; monthly cap 16 dosing days	Nausea; rare hepatotoxicity	Not vasoconstrictive — cardiovascular disease is not a contraindication.
Ubrogepant Alternative	Triptan-contraindicated or triptan-non-responsive	50-100 mg PO, may repeat after ≥2h; max 200 mg/24h; monthly cap 16 dosing days	Nausea, somnolence	Avoid with strong CYP3A4 inhibitors. Not vasoconstrictive.
Metoclopramide Preferred	Antiemetic adjunct, any severity tier	10 mg PO/IV; max 60 mg/day	Akathisia, extrapyramidal symptoms (rare)	Also has independent anti-migraine effect, not just antiemetic.
Prochlorperazine Alternative	Antiemetic adjunct, any severity tier	10 mg PO; max 40 mg/day	Sedation, extrapyramidal symptoms (rare)	Alternative to metoclopramide with similar dual antiemetic/analgesic effect.
Propranolol Preferred	1st-line oral preventive	Start 20-40 mg BID, titrate to target 80-160 mg/day	Fatigue, hypotension, bradycardia, bronchospasm	Strong CHS recommendation. Give an adequate trial (target dose x 8-12 weeks) before judging failure.
Candesartan Preferred	1st-line oral preventive	Start 4-8 mg daily, titrate to target 16 mg daily (up to 32 mg)	Dizziness, hyperkalemia, hypotension	Upgraded to a strong recommendation for episodic migraine in the 2024 CHS update.
Amitriptyline Preferred	1st-line oral preventive	Start 10 mg qHS, titrate to target 25-75 mg qHS	Anticholinergic effects, sedation, weight gain	Take at bedtime given sedation. Useful when comorbid insomnia or tension-type headache overlap.
Topiramate Alternative	Oral preventive, weaker evidence grade	Start 15-25 mg qHS, titrate weekly to target 50-100 mg/day divided BID	Paresthesia, cognitive slowing, weight loss, nephrolithiasis, teratogenicity	Downgraded to a weak recommendation for episodic migraine in 2024. Contraindicated in pregnancy; can reduce hormonal contraceptive efficacy.
Erenumab Preferred	CGRP monoclonal antibody, episodic or chronic migraine	70 mg or 140 mg SC monthly	Injection-site reaction, constipation	Assess response after 3 monthly doses. Typically requires documented failure of 2+ oral preventives for reimbursement.
OnabotulinumtoxinA Preferred	Chronic migraine specifically (≥15 headache days/month, ≥8 migrainous)	155-195 units IM, PREEMPT protocol, every 12 weeks	Neck weakness, ptosis, injection-site pain	Chronic-migraine-specific indication — not used for episodic migraine. Administered by a trained specialist.

Special Populations

Pregnancy

Acute treatment: acetaminophen is the preferred first-line option throughout pregnancy. NSAIDs should generally be avoided, particularly from the third trimester onward (premature ductus arteriosus closure, oligohydramnios). Sumatriptan has the largest body of pregnancy-registry experience of any triptan and has not shown a consistent increased risk of major congenital malformation — it can reasonably be used when acetaminophen and non-pharmacologic measures are inadequate and the benefit outweighs the risk.^[5] Ergotamine and dihydroergotamine are contraindicated (uterotonic/vasoconstrictive). Opioids should be avoided given dependence and neonatal withdrawal risk.

Preventive therapy: avoid drug prevention in pregnancy where possible, favouring trigger management and non-pharmacologic measures. If prevention is genuinely needed, a beta-blocker such as propranolol is the first choice, with amitriptyline as a second-line option.^[5] Topiramate and candesartan are contraindicated in pregnancy — teratogenic risk (topiramate: oral clefts, low birth weight) and fetotoxicity (candesartan, an ARB), respectively. CGRP monoclonal antibodies are not recommended in pregnancy given insufficient human safety data; discontinue before conception where feasible given their long half-life.

Breastfeeding

Acetaminophen, ibuprofen, and sumatriptan (minimal transfer into breast milk) are considered compatible with breastfeeding. Propranolol and amitriptyline are also generally compatible with monitoring. Topiramate is present in breast milk in measurable amounts — use with infant monitoring. Avoid opioids and ergotamine/dihydroergotamine.

Migraine with aura and hormonal contraception

Combined hormonal contraceptives (estrogen-containing) meaningfully increase ischemic stroke risk in patients with migraine with aura and should generally be avoided in this group in favour of progestin-only or non-hormonal contraception — this applies regardless of age or smoking status.

Menstrual migraine

For predictable perimenstrual attacks, options include standard acute treatment, short-term "mini-prophylaxis" with a longer-acting triptan (frovatriptan or naratriptan) started a few days before the expected attack window and continued through it, or continuous/extended-cycle hormonal contraception to reduce estrogen withdrawal — the latter two are best arranged with specialist input.

Hemiplegic and brainstem-aura migraine

Avoid triptans and dihydroergotamine given their vasoconstrictive mechanism; favour NSAIDs, antiemetics, and gepants for acute treatment instead.

Monitoring & Follow-Up

Track headache days, migraine days, and acute-medication treatment days per month with a diary or tracking app at every follow-up — this single habit catches both inadequate control and emerging medication overuse before either becomes entrenched.^[4]
For a new or adjusted oral preventive, reassess at the target or maximally tolerated dose after 8-12 weeks before judging efficacy — a common and avoidable error is abandoning a preventive too early.
The standard responder benchmark for preventive therapy is a 50% or greater reduction in monthly headache or migraine days.^[6]
For a CGRP monoclonal antibody, assess response after 3 monthly doses (or after the first quarterly dose for agents dosed every 3 months); if inadequate, consider switching within the class, to onabotulinumtoxinA (chronic migraine), or addressing an unrecognized medication-overuse pattern before concluding the class has failed.
Periodically reassess ongoing need for preventive therapy — a supervised taper trial is reasonable after a sustained period of good control, commonly 6-12 months, individualized to the patient.
Screen for comorbid depression, anxiety, and sleep disruption at follow-up given their bidirectional relationship with migraine burden.

Treatment Failure / Next Step

Reconfirm the diagnosis — reassess for red flags and secondary causes, especially if the headache pattern has genuinely changed rather than simply persisted.
Confirm the acute agent was taken early in the attack, at an adequate dose, and by a route appropriate to the attack (switch to a nasal spray, subcutaneous injection, or orally-dissolving tablet if nausea/vomiting is limiting oral absorption).
Screen for and address medication overuse headache before judging any acute or preventive agent to have failed — an overused acute medication blunts response to everything, including preventive therapy, and often needs to be tapered/withdrawn first.
Before abandoning the triptan class, try a second triptan — response is agent-specific, not fully predictable from class, and a meaningful proportion of patients who fail one triptan respond to another.
If a full acute-medication class fails or is contraindicated, move to a mechanistically different option (NSAID failure → triptan; triptan failure/contraindication → gepant).
For preventive therapy, confirm an adequate trial (target/tolerated dose sustained 8-12 weeks) was actually completed before switching; if a genuine adequate trial has failed, move to a different first-line oral class or escalate to a CGRP monoclonal antibody, or to onabotulinumtoxinA specifically for chronic migraine.
Refer to a headache specialist or neurology for refractory migraine (failure of multiple preventive classes), suspected hemiplegic or brainstem-aura migraine, status migrainosus (a debilitating attack lasting beyond 72 hours), or genuine diagnostic uncertainty.

Common Errors to Avoid

Ordering routine neuroimaging in a patient who meets migraine criteria, has a normal examination, and has no red flags.^[3]
Prescribing opioids or butalbital-containing combination analgesics as first-line acute therapy — NSAIDs and triptans are first-line, and opioids raise both dependence and chronification risk.^[3]
Not asking specifically about acute-medication treatment days per month — the single most commonly missed history item, and the one that catches evolving medication overuse headache.
Declaring a triptan a "failure" after a single unsuccessful attack, or after taking it too late in the attack, rather than confirming an adequate trial (typically 2-3 attacks, taken early).
Not offering a second triptan after the first one fails — response is agent-specific.
Using a triptan or dihydroergotamine in a patient with hemiplegic migraine, brainstem-aura migraine, or a significant cardiovascular contraindication.
Continuing topiramate in a patient who could become pregnant without an explicit teratogenicity and contraceptive-reliability discussion — topiramate can reduce combined hormonal contraceptive efficacy at higher doses.
Prescribing combined (estrogen-containing) hormonal contraception to a patient with migraine with aura.
Declaring a preventive agent a "failure" before completing an adequate trial — target or maximally tolerated dose sustained for 8-12 weeks.
Escalating straight to a CGRP monoclonal antibody or onabotulinumtoxinA without first identifying and addressing medication overuse headache, since an overused acute agent blunts the response to any preventive.
Focusing on drug selection while neglecting the non-pharmacologic foundations — sleep regularity, regular meals, hydration, and stress management.

Clinical Decision Algorithm

Algorithm A — Initial assessment and red-flag triage

New or changed headache pattern presenting for assessment

Take history and neurologic exam; screen for SNOOP red flags (systemic signs, neurologic deficit, sudden/thunderclap onset, onset after age 50, pattern change/positional/precipitated by Valsalva)

Any red flag present

Do not manage as routine migraine — urgent neuroimaging and/or emergency assessment per the specific red flag

No red flags, meets ICHD-3 migraine criteria

Diagnose migraine clinically (no routine imaging needed); classify with vs. without aura, and episodic vs. chronic (≥15 headache days/month with ≥8 migrainous, >3 months)

Algorithm B — Acute attack treatment (stratified care)

Acute migraine attack — assess usual attack severity/disability and prior treatment response

Mild-moderate, not significantly disabling

NSAID (naproxen/ibuprofen/diclofenac potassium/ASA) or acetaminophen, taken early; add an antiemetic if nauseated

Adequate relief

Continue; monitor use frequency (under 15 days/month)

Inadequate relief

Step up to a triptan (or sumatriptan/naproxen combination) for this and future attacks

Moderate-severe, or significantly disabling regardless of severity

Start directly with a triptan, formulation matched to the attack (nasal spray/SC or ODT if nausea/rapid escalation; longer-half-life agent if frequent recurrence)

Cardiovascular contraindication, hemiplegic/brainstem-aura migraine, or confirmed triptan non-response

Switch to a gepant (rimegepant or ubrogepant) — not vasoconstrictive, no cardiovascular contraindication

Triptan effective but attacks recur, or breakthrough nausea

Add an antiemetic and/or combine with an NSAID; try a second triptan before abandoning the class

At every visit: count acute-treatment days/month — triptans/gepants/ergots/combination analgesics under 10 days, NSAIDs/acetaminophen under 15 days, or medication overuse headache risk rises

Algorithm C — Preventive therapy escalation

Preventive therapy indicated: ≥4 monthly headache days poorly responsive to acute treatment, ≥8 monthly headache days even when acute treatment works, or high disability/overuse risk

First-line oral agent — propranolol, candesartan, or amitriptyline (topiramate a weaker-evidence alternative); slow titration, adequate trial = target/tolerated dose sustained 8-12 weeks

≥50% reduction in monthly headache/migraine days

Continue; reassess periodically, consider a supervised taper after sustained control (individualized, commonly 6-12 months)

Inadequate response after a genuine adequate trial, or not tolerated

Switch to a different first-line oral class, or escalate to a CGRP monoclonal antibody (erenumab/fremanezumab/galcanezumab/eptinezumab)

Chronic migraine (≥15 headache days/month, ≥8 migrainous, >3 months) with inadequate response

OnabotulinumtoxinA (PREEMPT protocol), alone or combined with a CGRP monoclonal antibody

Before escalating further

Confirm medication overuse headache has been identified and addressed — an overused acute agent blunts response to every preventive

Drug Tables

How to use this table: Doses are adult doses and require patient-specific confirmation, including renal/hepatic adjustment and pregnancy status. Select any drug name to open its complete Pharmasist Drug Database page.

Simple analgesics and NSAIDs (acute, mild-moderate attacks)

1st-line acute options. Cap use at under 15 treatment days/month to avoid medication overuse headache.

Drug	Dosage	Adverse effects	Drug interactions	Comments
Acetaminophen	1000 mg PO; max 4000 mg/day (8 x 500 mg)	Hepatotoxicity at high cumulative dose	Caution with other acetaminophen-containing products	Preferred simple analgesic when NSAIDs are contraindicated.
Acetylsalicylic acid (ASA)	500-1000 mg PO q4-6h; max 4000 mg/day	GI upset, GI bleed, tinnitus at high dose	Increased bleeding with anticoagulants; avoid with other NSAIDs	Effervescent formulation may act faster.
Naproxen / naproxen sodium	500-550 mg PO BID; max 1100 mg/day	GI upset, dyspepsia; GI bleed risk with chronic use	Increased bleeding with anticoagulants; avoid with other NSAIDs	NSAID component of the sumatriptan/naproxen combination product.
Ibuprofen	400 mg PO q4h; max 2400 mg/day	GI upset, dyspepsia	Increased bleeding with anticoagulants; avoid with other NSAIDs
Diclofenac potassium	50 mg PO (tablet or dissolvable powder); max 150 mg/day	GI upset, dyspepsia	Increased bleeding with anticoagulants; avoid with other NSAIDs	Powder formulation (Cambia) gives faster absorption than the tablet.
Indomethacin	25-100 mg PO, or 50-100 mg PR; max 200 mg/day	GI upset, headache, dizziness	Increased bleeding with anticoagulants; avoid with other NSAIDs	Suppository formulation useful when oral intake is limited by nausea/vomiting.
Ketorolac	10 mg PO (max 40 mg/day), or 30 mg IM (max 120 mg/day)	GI upset, GI bleed	Increased bleeding with anticoagulants; avoid with other NSAIDs	Injectable option for a rapidly escalating or refractory attack in an acute-care setting.

Triptans (acute, moderate-severe attacks)

Monthly cap of 10 dosing days. For all triptans except eletriptan, 2 doses are allowed in 24 hours (Canadian labelling limits eletriptan to 1 dose/24h, though many experts allow 2); the second dose can be taken 2 hours after the first for almotriptan, eletriptan, rizatriptan, sumatriptan, and zolmitriptan, and 4 hours after the first for frovatriptan and naratriptan.

Drug	Dosage	Adverse effects	Drug interactions	Comments
Sumatriptan	50-100 mg PO tablet, or 20 mg intranasal, or 6 mg SC	Chest/neck/jaw tightness, paresthesia, flushing, fatigue	Avoid within 24h of ergotamine/DHE or another triptan; avoid with MAOIs	SC injection and nasal spray are the fastest-onset options and preferred with nausea/vomiting.
Rizatriptan	5-10 mg PO tablet or orally-dissolving tablet	Chest/neck/jaw tightness, paresthesia, fatigue	Avoid within 24h of ergotamine/DHE or another triptan; avoid with MAOIs	Orally-dissolving tablet does not require water.
Zolmitriptan	2.5 mg PO tablet or orally-dissolving tablet, or 2.5-5 mg intranasal	Chest/neck/jaw tightness, paresthesia, fatigue	Avoid within 24h of ergotamine/DHE or another triptan; avoid with MAOIs	Nasal spray formulation is a preferred route for rapid-onset attacks.
Eletriptan	20-40 mg PO tablet	Chest/neck/jaw tightness, paresthesia, fatigue	Avoid strong CYP3A4 inhibitors; avoid within 24h of ergotamine/DHE or another triptan	Canadian labelling limits the 40 mg dose to once/24h.
Almotriptan	6.25-12.5 mg PO tablet	Chest/neck/jaw tightness, paresthesia, fatigue	Avoid within 24h of ergotamine/DHE or another triptan; avoid with MAOIs
Naratriptan	1-2.5 mg PO tablet	Chest/neck/jaw tightness, paresthesia, fatigue	Avoid within 24h of ergotamine/DHE or another triptan; avoid with MAOIs	Longer half-life — an option for attacks with frequent recurrence, and for perimenstrual mini-prophylaxis.
Frovatriptan	2.5 mg PO tablet	Chest/neck/jaw tightness, paresthesia, fatigue	Avoid within 24h of ergotamine/DHE or another triptan; avoid with MAOIs	Longest half-life of the triptans — an option for attacks with frequent recurrence, and for perimenstrual mini-prophylaxis.
Sumatriptan/naproxen (combination)	85 mg/500 mg PO tablet; max 2 tablets/day	Combines the adverse effects of both components	As per each component	For suboptimal response to triptan or NSAID monotherapy alone.

Gepants (acute, triptan-contraindicated or triptan-non-responsive)

Monthly cap of 16 dosing days. Not vasoconstrictive — cardiovascular disease is not a contraindication and cardiovascular risk factors are not a precaution.

Drug	Dosage	Adverse effects	Drug interactions	Comments
Ubrogepant	50-100 mg PO, may repeat after ≥2h; max 200 mg/24h	Nausea, somnolence, dry mouth	Avoid strong/moderate CYP3A4 inhibitors and strong CYP3A4 inducers	First gepant approved for acute treatment in Canada.
Rimegepant	75 mg PO orally-dissolving tablet; once per 24h only	Nausea; rare transaminase elevation	Avoid strong CYP3A4 inhibitors and strong CYP3A4 inducers	Also has an approved preventive dosing regimen (75 mg every other day) — distinct indication from PRN acute use.

Ergotamine derivatives

Second-line, generally specialist-initiated given administration complexity and lower tolerability than triptans/gepants.

Drug	Dosage	Adverse effects	Drug interactions	Comments
Dihydroergotamine (DHE)	2 mg intranasal, or 1 mg SC/IM	Nausea, vasoconstriction, chest tightness	Contraindicated with triptans within 24h, with potent CYP3A4 inhibitors, and with other vasoconstrictors	Contraindicated in cardiovascular disease, hemiplegic/brainstem-aura migraine, and pregnancy. Repeated intranasal use can irritate the nasal mucosa.

Antiemetics (adjunct for nausea/vomiting)

Drug	Dosage	Adverse effects	Drug interactions	Comments
Metoclopramide	10 mg PO/IV; max 60 mg/day	Akathisia, extrapyramidal symptoms (rare)	Additive extrapyramidal risk with other dopamine antagonists	Also has independent anti-migraine analgesic effect, not just antiemetic.
Prochlorperazine	10 mg PO; max 40 mg/day	Sedation, extrapyramidal symptoms (rare)	Additive sedation/extrapyramidal risk with other dopamine antagonists	Alternative to metoclopramide with a similar dual antiemetic/analgesic effect.
Dimenhydrinate	50-100 mg PO or PR; max 400 mg/day	Sedation, anticholinergic effects	Additive sedation with other CNS depressants
Ondansetron	4-8 mg PO/ODT; max 32 mg/day	Headache, constipation, QT prolongation at high dose	Additive QT prolongation with other QT-prolonging drugs	No independent anti-migraine effect — antiemetic action only.
Domperidone	10 mg PO; per current product monograph	QT prolongation, rare cardiac arrhythmia	Avoid with strong CYP3A4 inhibitors and other QT-prolonging drugs	Health Canada boxed warning for cardiac risk — use the lowest effective dose.

Preventive therapy — first-line oral agents

Titrate slowly; give an adequate trial (target/tolerated dose sustained 8-12 weeks) before judging failure.

Drug	Dosage	Adverse effects	Drug interactions	Comments
Propranolol	Start 20-40 mg BID (or 60-80 mg long-acting daily), titrate to target 80-160 mg/day (up to 240 mg/day)	Fatigue, hypotension, bradycardia, bronchospasm, vivid dreams	Additive bradycardia with other rate-limiting agents; caution with verapamil/diltiazem	Strong CHS recommendation. Avoid in asthma/reactive airway disease and decompensated heart failure.
Nadolol	Start 20-40 mg daily, titrate to target 40-160 mg/day	Fatigue, hypotension, bradycardia, bronchospasm	Additive bradycardia with other rate-limiting agents	Alternative beta-blocker; once-daily dosing.
Candesartan	Start 4-8 mg daily, titrate to target 16 mg daily (up to 32 mg)	Dizziness, hyperkalemia, hypotension	Hyperkalemia risk with potassium-sparing diuretics	Upgraded to a strong recommendation for episodic migraine in the 2024 CHS update. Contraindicated in pregnancy.
Amitriptyline	Start 10 mg qHS, titrate by 10-25 mg every 1-2 weeks to target 25-75 mg qHS (up to 150 mg)	Anticholinergic effects, sedation, weight gain, QT prolongation at high dose	Avoid with MAOIs; additive sedation/anticholinergic burden with other agents	Take at bedtime. Useful with comorbid insomnia or tension-type overlap.
Nortriptyline	Start 10 mg qHS, titrate to target 25-75 mg qHS	Anticholinergic effects (less than amitriptyline), sedation	Avoid with MAOIs	Alternative tricyclic with a more favourable side-effect profile than amitriptyline.
Topiramate	Start 15-25 mg qHS, titrate weekly by 15-25 mg to target 50-100 mg/day divided BID	Paresthesia, cognitive slowing, weight loss, nephrolithiasis, teratogenicity	May reduce hormonal contraceptive efficacy at higher doses; additive CNS effects with other agents	Downgraded to a weak recommendation for episodic migraine in 2024. Contraindicated in pregnancy.
Venlafaxine (extended-release)	Start 37.5 mg daily, titrate to target 75-150 mg daily	Nausea, hypertension at higher dose, discontinuation syndrome	Avoid with MAOIs; caution with other serotonergic agents	Reasonable alternative, particularly with comorbid depression/anxiety.

Preventive therapy — CGRP-targeted and chronic-migraine-specific options

Strong recommendation across episodic and chronic migraine. Canadian drug plans typically require documented failure of 2 or more conventional oral preventives first.

Drug	Dosage	Adverse effects	Drug interactions	Comments
Erenumab	70 mg or 140 mg SC monthly	Injection-site reaction, constipation	None significant	Assess response after 3 monthly doses.
Fremanezumab	225 mg SC monthly, or 675 mg SC every 3 months	Injection-site reaction	None significant	Quarterly dosing option improves adherence for some patients.
Galcanezumab	Loading dose 240 mg SC (two 120 mg injections), then 120 mg SC monthly	Injection-site reaction	None significant
Eptinezumab	100 mg or 300 mg IV every 3 months	Infusion-related reaction, nasopharyngitis	None significant	Only CGRP monoclonal antibody given by IV infusion rather than SC injection.
OnabotulinumtoxinA	155-195 units IM, PREEMPT protocol (31-39 sites, head/neck), every 12 weeks	Neck weakness, ptosis, injection-site pain	Caution with other agents affecting neuromuscular transmission (e.g., aminoglycosides)	Chronic-migraine-specific indication (≥15 headache days/month, ≥8 migrainous, >3 months) — not indicated for episodic migraine. Administered by a trained specialist.

Evidence note: Drug inventory, dosing, monthly caps, and comments reflect standard Canadian practice, cross-checked against the Canadian Headache Society acute^[5] and preventive^[2] guidelines and the Migraine Canada 2025 Adult Acute Dosing Guide^[4].

References

Diagnosis and acute management of migraine — CMAJ (Tzankova V, Becker WJ, Chan TLH). CMAJ 2023;195(4):E153-E158
Updated Canadian Headache Society Migraine Prevention Guideline with Systematic Review and Meta-analysis — Canadian Journal of Neurological Sciences, Canadian Headache Society (Medrea I, Cooper P, Lagman-Bartolome AM, et al.). Can J Neurol Sci 2024;52(3):450-472
Headache: Four Things Physicians and Patients Should Question — Canadian Headache Society, in partnership with Choosing Wisely Canada. Choosing Wisely Canada, last updated June 2017
Acute Medications for Adults: Essential Principles and Dosing Guide — Migraine Canada. Migraine Canada, 2025
Canadian Headache Society Guideline: Acute Drug Therapy for Migraine Headache — Canadian Journal of Neurological Sciences, Canadian Headache Society Acute Migraine Treatment Guideline Development Group (Worthington I, Pringsheim T, Gawel MJ, et al.). Can J Neurol Sci 2013;40(5 Suppl 3):S1-S80
Pharmacologic prevention of migraine — CMAJ (Tzankova V, Becker WJ, Chan TLH). CMAJ 2023;195(5):E187-E192

Professional reference only. Apply clinical judgment and verify patient-specific decisions against current authoritative guidance and product information.