Primary headaches include tension-type headache (most common — bilateral, pressure-like, mild-to-moderate, no nausea), migraine (unilateral, pulsating, moderate-to-severe, with nausea and/or light/sound sensitivity, often with prodrome), and cluster headache (severe unilateral periorbital pain with autonomic features — tearing, rhinorrhea — in cyclical patterns). Migraine is frequently misdiagnosed as 'sinus headache' or tension headache, leading to years of inadequate treatment.
Secondary headaches require investigation. The SNOOP4 mnemonic captures key red flags: Systemic signs (fever, weight loss, HIV), Neurological symptoms (focal deficits, altered consciousness), Onset sudden ('thunderclap' — worst headache of life, maximal at onset), Older age (>50, new headache type), Positional change (worse lying down — raises ICP), Prior history of cancer, Papilledema, Pregnancy. Any of these features warrants urgent imaging.
Thunderclap headache — a headache reaching maximum intensity within 60 seconds — must be treated as subarachnoid hemorrhage until proven otherwise. CT head is the first-line test (90%+ sensitivity in first 6 hours). If CT is negative but clinical suspicion remains, lumbar puncture looking for xanthochromia is the next step. Subarachnoid hemorrhage is a neurosurgical emergency with high mortality — the window for intervention is narrow.
Migraine treatment is tiered: acute (triptans are first-line for moderate-severe migraine, NSAIDs and antiemetics for mild-moderate), preventive (for ≥4 headache days/month — topiramate, propranolol, amitriptyline, CGRP monoclonal antibodies), and non-pharmacological (trigger identification, sleep regulation, stress management). CGRP pathway antagonists (erenumab, fremanezumab, ubrogepant) represent a transformative class with excellent efficacy and tolerability.