Migraine — preventive therapy

Red Flags

Thunderclap headache, focal neurological deficit, papilloedema, fever, or new headache after age 50 — exclude secondary cause before labelling migraine^[1]
Medication overuse headache (≥10 days/month of triptan/opioid/combination analgesic, or ≥15 days/month of simple analgesic) — withdraw overused agent and start preventive^[1]
Migraine with aura plus combined oral contraceptive — increased ischaemic stroke risk; avoid CHC, use progestogen-only or non-hormonal contraception^[1]
Pregnancy or planning pregnancy on topiramate or valproate — both teratogenic; switch to safer preventive (propranolol, magnesium) and add folate^[1]

First-line treatment

Interventions

Indication for preventive therapy^[1]
Offer preventive therapy when migraine causes ≥3 days/month of significant disability, ≥4 headache days/month, contraindication or overuse of acute therapy, or chronic migraine (≥15 headache days/month)
Lifestyle and trigger management^[1]
Regular sleep, hydration, meals; aerobic exercise 3–5×/week; stress reduction (CBT, mindfulness, biofeedback); identify and modify individual triggers via diary

First-line drug therapy

Drug	Class	Adult	Paediatric	Notes
Propranolol^[1]	Non-selective beta-blocker	Start 40 mg PO BD; titrate to 80–240 mg/day in divided doses	Adolescents: 1–4 mg/kg/day in divided doses	Level A evidence; first-line oral preventive especially with comorbid hypertension; avoid in asthma, bradycardia, severe depression
Topiramate^[1]	Antiseizure (sodium channel + GABA + glutamate)	Start 25 mg PO at night; titrate by 25 mg weekly to 100 mg/day in divided doses; max 200 mg	≥12 years: 1–3 mg/kg/day	Level A evidence including chronic migraine; avoid in pregnancy, kidney stones, low BMI; cognitive side effects, paraesthesia, weight loss
Amitriptyline^[1]	Tricyclic antidepressant	Start 10–25 mg PO at night; titrate to 50–75 mg/day	Adolescents: 0.25–1 mg/kg/night	Level B evidence; first choice with comorbid tension-type headache, insomnia, depression, neuropathic pain; sedation, dry mouth, weight gain, urinary retention
Candesartan^[1]	Angiotensin II receptor antagonist	16 mg PO once daily; up to 32 mg	—	Level B evidence; well tolerated alternative when beta-blocker contraindicated; useful in hypertension
Erenumab / fremanezumab / galcanezumab^[1]	Anti-CGRP or anti-CGRP-receptor monoclonal antibody	Erenumab 70–140 mg SC monthly; fremanezumab 225 mg SC monthly or 675 mg quarterly; galcanezumab 240 mg SC loading then 120 mg monthly	—	First-line option per AHS 2024 — no requirement to fail oral preventives first; episodic and chronic migraine; constipation (erenumab) and injection site reactions
Atogepant or rimegepant (gepants)^[1]	Small-molecule CGRP receptor antagonist	Atogepant 10–60 mg PO once daily for prevention; rimegepant 75 mg PO every other day	—	Oral preventive class; episodic migraine; rimegepant covers both acute and prevention; avoid concurrent strong CYP3A4 inhibitors with atogepant
Onabotulinumtoxin A^[1]	Neurotoxin, neuromuscular blocker	155–195 U IM across 31–39 sites every 12 weeks (PREEMPT protocol)	—	Chronic migraine only (≥15 headache days/month); not effective for episodic migraine; specialist administration
Magnesium citrate or oxide (adjunctive)^[1]	Mineral supplement	400–600 mg elemental Mg PO daily	—	Adjunctive Level B evidence; well tolerated; diarrhoea is dose-limiting; reasonable in pregnancy

Propranolol^[1]

Non-selective beta-blocker

Adult: Start 40 mg PO BD; titrate to 80–240 mg/day in divided doses
Paediatric: Adolescents: 1–4 mg/kg/day in divided doses

Level A evidence; first-line oral preventive especially with comorbid hypertension; avoid in asthma, bradycardia, severe depression

Topiramate^[1]

Antiseizure (sodium channel + GABA + glutamate)

Adult: Start 25 mg PO at night; titrate by 25 mg weekly to 100 mg/day in divided doses; max 200 mg
Paediatric: ≥12 years: 1–3 mg/kg/day

Level A evidence including chronic migraine; avoid in pregnancy, kidney stones, low BMI; cognitive side effects, paraesthesia, weight loss

Amitriptyline^[1]

Tricyclic antidepressant

Adult: Start 10–25 mg PO at night; titrate to 50–75 mg/day
Paediatric: Adolescents: 0.25–1 mg/kg/night

Level B evidence; first choice with comorbid tension-type headache, insomnia, depression, neuropathic pain; sedation, dry mouth, weight gain, urinary retention

Candesartan^[1]

Angiotensin II receptor antagonist

Adult: 16 mg PO once daily; up to 32 mg
Paediatric: —

Level B evidence; well tolerated alternative when beta-blocker contraindicated; useful in hypertension

Erenumab / fremanezumab / galcanezumab^[1]

Anti-CGRP or anti-CGRP-receptor monoclonal antibody

Adult: Erenumab 70–140 mg SC monthly; fremanezumab 225 mg SC monthly or 675 mg quarterly; galcanezumab 240 mg SC loading then 120 mg monthly
Paediatric: —

First-line option per AHS 2024 — no requirement to fail oral preventives first; episodic and chronic migraine; constipation (erenumab) and injection site reactions

Atogepant or rimegepant (gepants)^[1]

Small-molecule CGRP receptor antagonist

Adult: Atogepant 10–60 mg PO once daily for prevention; rimegepant 75 mg PO every other day
Paediatric: —

Oral preventive class; episodic migraine; rimegepant covers both acute and prevention; avoid concurrent strong CYP3A4 inhibitors with atogepant

Onabotulinumtoxin A^[1]

Neurotoxin, neuromuscular blocker

Adult: 155–195 U IM across 31–39 sites every 12 weeks (PREEMPT protocol)
Paediatric: —

Chronic migraine only (≥15 headache days/month); not effective for episodic migraine; specialist administration

Magnesium citrate or oxide (adjunctive)^[1]

Mineral supplement

Adult: 400–600 mg elemental Mg PO daily
Paediatric: —

Adjunctive Level B evidence; well tolerated; diarrhoea is dose-limiting; reasonable in pregnancy

Safety-net

Allow at least 8 weeks of preventive at therapeutic dose before judging effectiveness — earlier abandonment misses real responders^[1]
Track headache days, attack severity, and analgesic use in a diary — gives both you and the clinician objective response data^[1]
If frequency suddenly worsens, attacks change character, or new symptoms appear (vision change, weakness, fever) — same-day medical review^[1]

Referral criteria

Headache with red flag featuresNeurology and brain imaging same-day if acute^[1]
Failure of ≥2 oral preventives at adequate dose and durationHeadache specialist for CGRP-targeted therapy or onabotulinumtoxin A^[1]
Chronic migraine (≥15 days/month) with disabilityHeadache specialist for chronic migraine pathway^[1]
Migraine in pregnancy or breastfeeding requiring preventiveJoint neurology and obstetric clinic^[1]

Clinical summary

Indication for and selection of preventive medication in episodic and chronic migraine, including oral first-line agents and CGRP-targeted therapy.

References

1.American Headache Society Position Statement on Integrating New Migraine Treatments into Clinical Practice (2024 update); AAN/AHS Evidence-based Guideline Update: Pharmacologic Treatment for Episodic Migraine Prevention (2024)