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what is headache?

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"headache"[MeSH Terms] AND classification

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what is headache definition types causes

Headache

A headache is pain or discomfort felt anywhere in the head, scalp, or upper neck, ranging from a mild dull ache to severe, incapacitating pain. It's one of the most common medical complaints and can occur on its own or as a symptom of another condition.

Two broad categories

1. Primary headaches - the headache itself is the disorder, not caused by another underlying disease. The main types are:
  • Tension-type headache - the most common type; a mild-to-moderate, band-like pain around the whole head, without nausea/vomiting, and with at most one of photophobia (light sensitivity) or phonophobia (sound sensitivity) - Goldman-Cecil Medicine
  • Migraine - an inherited headache disorder, typically unilateral (one-sided) but sometimes bilateral, moderate-to-severe, worsened by routine physical activity, and accompanied by nausea and/or vomiting, often with light and sound sensitivity - Goldman-Cecil Medicine
  • Cluster headache (and related trigeminal autonomic cephalalgias) - unilateral headaches accompanied by autonomic features on the same side, such as tearing, eye redness, or nasal congestion - Goldman-Cecil Medicine
  • Chronic daily headache - not a single disorder but a pattern defined as headache present on more than 15 days per month - Goldman-Cecil Medicine
2. Secondary headaches - occur as a symptom of an underlying problem, such as:
  • Sinus infection, dehydration, or eye strain (usually benign)
  • Hypertensive headache (blood pressure typically above 180/120, a medical emergency)
  • Post-traumatic headache (after head injury)
  • Spinal headache (after spinal fluid leak, e.g. following a lumbar puncture)
  • Rebound headache (from overuse of pain medication)
  • Thunderclap headache (sudden, severe onset - a red flag for serious causes like subarachnoid hemorrhage)

When it matters clinically

Duration, location, and associated features help distinguish types - for example, migraine by International Headache Society criteria typically requires attacks lasting at least 4 hours (untreated), while tension-type headache is holocranial (whole-head) without the nausea seen in migraine. Sudden, severe ("thunderclap") headaches or those with fever, neurological deficits, or occurring after trauma warrant urgent medical evaluation to rule out dangerous secondary causes.
Recent systematic reviews (PMID: 40217141, on biomarkers for differentiating primary headache disorders, and PMID: 39028222, on post-traumatic headache phenotypes) reflect ongoing research into better diagnostic tools, but don't change the core definitions above.
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