Decision support only — for the patient who presents acutely (often vomiting, dehydrated, or in status migrainosus >72h) and has failed their usual oral treatment. Outpatient choice of regimen, prevention, and medication-overuse limits live on the community sheet. Two rules dominate here: exclude secondary headache, and don't reach for opioids. Verify all doses.
1 Parenteral treatment — what the evidence supports
First-linestart together
Acute attack needing parenteral therapy.
IV prochlorperazine must offer or metoclopramide, + greater occipital nerve block must offer. Add IV ketorolac/dexketoprofen and/or SC sumatriptan; IV fluids. Co-give an antihistamine to cover akathisia.
Refractory / status>72h or no response
Not settling on first-line.
Dihydroergotamine (severe/status), IV valproate, or IV magnesium (most useful with aura). Involve neurology; consider admission.
Before dischargestop the bounce-back
Responding, planning discharge.
IV dexamethasone — reduces 24–72h recurrence Colman BMJ (give as well as, not instead of, an abortive). Arrange follow-up; flag overuse for the outpatient plan.
Opioids (incl. hydromorphone) must not be offered — Level A against: poor efficacy, more recurrence, return visits, and dependence. Anti-dopaminergics work as migraine treatments in their own right, not just as antiemetics — but watch for akathisia/dystonia (higher with prochlorperazine than metoclopramide) and QT prolongation.
2 Exclude secondary headache first
Red flags — don't anchor on migraine
- OnsetThunderclap (peak <1 min), "first or worst," or a clear change from the usual pattern.
- SignsFever/meningism, focal deficit, papilloedema, reduced GCS, new seizure.
- ContextNew onset >50, immunocompromised/cancer, pregnancy or postpartum, positional or Valsalva-triggered.
The work-up it points to
- SAHNon-contrast CT; if >6h from onset or CT negative with ongoing suspicion → LP (xanthochromia) ± CTA.
- CVSTPregnancy/postpartum, prothrombotic, or papilloedema → CT/MR venogram.
- GCAAge >50, jaw claudication, scalp tenderness → ESR/CRP, start steroid, refer.
- OtherMeningitis → LP; pregnancy + ↑BP → pre-eclampsia/PRES; sudden + endocrine → pituitary apoplexy.
3 Agents, doses & the cautions
Doses (verify locally)
- Prochlorperazine10 mg IV
- Metoclopramide10–20 mg IV
- Ketorolac10–30 mg IV/IM
- Sumatriptan6 mg SC
- Dexamethasone~10 mg IV (recurrence)
- Magnesium1–2 g IV
- Valproate~1 g IV
Cautions & disposition
- AkathisiaCo-give diphenhydramine with anti-dopaminergics (esp. prochlorperazine); watch dystonia & QTc.
- SpacingNo triptan + ergot/DHE within 24h of each other (vasospasm). DHE: avoid in CAD, uncontrolled HTN, pregnancy.
- PregnancyAvoid valproate & DHE; paracetamol, antiemetics, magnesium, GONB are the safer tools.
- Admit ifIntractable status, persistent vomiting/dehydration, or diagnostic uncertainty.
Sources.
Robblee et al. "2025 guideline update to acute treatment of migraine for adults in the emergency department: AHS evidence assessment of parenteral pharmacotherapies," Headache 2025 (prochlorperazine IV & GONB must-offer; metoclopramide/ketorolac/dexketoprofen/SC sumatriptan should-offer; chlorpromazine/dexamethasone/valproate may-offer; hydromorphone must-not-offer). Canadian Headache Society ED recommendations. eTG.
Key evidence: Colman et al, BMJ 2008 (parenteral dexamethasone reduces early migraine recurrence); AHS/AHRQ parenteral comparative-effectiveness reviews.
Caveats: dihydroergotamine and IV magnesium carry weaker/mixed evidence (level U in 2016) but remain options for refractory/status and aura respectively. Akathisia risk is higher with prochlorperazine than metoclopramide. Outpatient regimen choice, prevention, and overuse limits are on the companion community sheet. Verify all doses and contraindications.