Headache

at the bedside

any present → urgent CT ± LP / specialist

acute vs chronic; character, location, duration
primary patterns
- migraine → unilateral, throbbing, aura
- tension → band-like
- cluster → severe periorbital + autonomic
location clues (correlate with the full picture, not the site alone)
- occipital → cerebellar lesion, cervicogenic, cervical radiculopathy
- orbital → optic neuritis, cavernous sinus thrombosis
- facial → sinusitis, carotid artery dissection
ask: fever, photophobia, N/V; trauma; meds (OCPs, anticoagulants, analgesic overuse); PMH (cancer, pregnancy, autoimmune)
examine: neuro exam + GCS; meningeal signs; fundoscopy → papilledema; CN + visual fields; temporal artery (> 50 yrs)

CT brain: first-line for red flags; normal CT within 6 h of thunderclap onset effectively excludes SAH (LP if later or CT negative)
consider CTA head/neck: head or neck trauma; focal neurological deficit; suspected cervical artery dissection or other vascular pathology
consider CTV if cerebral venous sinus thrombosis suspected
- thunderclap, progressive, or positional headache resistant to usual analgesia; new seizure; focal deficit; papilledema
- risk factors: pregnancy / postpartum, hypercoagulable state, OCP, mastoiditis / local infection

no red flags, likely primary

paracetamol 1 g PO/IV q6h (max 4 g/day) or NSAID, ibuprofen 400 mg / naproxen 500 mg
ketorolac 15–30 mg IV or 30–60 mg IM, single dose; lower doses if over 65, renal impairment, or low body weight
- avoid: active or high-risk bleeding, peptic ulcer / GI bleed history, renal impairment, concurrent NSAID / aspirin
- not beyond 5 days if repeated
migraine → antiemetic (metoclopramide 10 mg IV or prochlorperazine 12.5 mg IV/IM) ± triptan (sumatriptan 50–100 mg PO / 6 mg SC)
- no triptans in IHD or uncontrolled HTN

red flags present

specific scenarios

hypertensive emergency → control BP, see the full hypertension treatment page
suspected SAH → CT now (6-h rule in imaging above); late or CT negative → LP; neurosurgery once confirmed
raised-ICP signs → urgent imaging, head-up 30°, neurosurgery
suspected bacterial meningitis → antibiotics now, do not delay
- ceftriaxone 2 g IV q12h + vancomycin 15–20 mg/kg IV q12h
- add ampicillin 2 g IV q4h if >50 y or immunocompromised (Listeria cover)
- dexamethasone 10 mg IV (≈0.15 mg/kg) with / just before the first antibiotic dose, then q6h ×4 days
- full regimens and alternatives: Empiric Antibiotics
suspected HSV encephalitis / meningoencephalitis → add acyclovir 10 mg/kg IV q8h empirically alongside bacterial cover while CSF HSV PCR and MRI are pending
- especially with altered mental status, seizures, or a focal / temporal-lobe picture
- do not wait for confirmation: missed HSV encephalitis carries major morbidity
suspected temporal arteritis (age > 50, new headache, jaw claudication, visual symptoms, tender / thickened temporal artery, raised ESR/CRP) → prednisolone 40–60 mg daily now, do not wait for biopsy
- visual symptoms or impending visual loss: high-dose IV methylprednisolone 500–1000 mg daily × 3 days, then oral
- urgent Ophthalmology + Rheumatology
acute angle-closure glaucoma (painful red eye, halos, fixed mid-dilated pupil, raised intraocular pressure) → urgent Ophthalmology; do not dilate the pupil

source	type
Ottawa SAH Rule · Perry et al, BMJ 2013 ↗︎	clinical decision rule
IDSA 2004 · Bacterial meningitis (empiric treatment)	specialty-society guidance
BSR/BHPR 2020 · Giant cell arteritis management	specialty-society guideline

Verify indication, dose, allergies, interactions, renal/hepatic function and local protocols before prescribing.

free the on-call checklist covers the whole shift on one printable page.

studying for the IM exam? the IM Rapid Review covers headache red flags in the same format. see the sample chapter.

reviewed Jun 2026updated Sep 2026file complaint/headache