Subdural haematoma

Also called Subdural haemorrhage or SDH

A subdural haematoma is a build-up of blood between the skull and the surface of the brain. It is usually caused by a head injury. In older people and people taking blood thinners, even a minor bump can cause one, and symptoms may develop slowly over days or weeks (chronic subdural haematoma).

Last updated Nov 9, 2026

What it is

Small haematomas may be watched with scans. Larger ones usually need surgery to drain the blood.

Recovery depends on the size and how quickly it is treated. Blood-thinning medicines may need to be stopped or changed for a while.

Common signs

  • A headache that keeps getting worse
  • Confusion or drowsiness
  • Feeling or being sick
  • Weakness on one side of the body
  • Slurred speech
  • Changes in behaviour or memory

How it is usually diagnosed

  • CT brain scan
  • Sometimes an MRI scan

Records worth keeping

Keeping these together makes each appointment easier, especially when you see a new doctor:

  • CT and MRI reports
  • Neurosurgery letters
  • Discharge letters
  • Medicine lists, including blood thinners

Questions to ask your doctor

  • Does it need to be drained?
  • What should I do about my blood thinners?
  • Which symptoms mean I should come back?

When to get help right away

Call 112 or go to the nearest emergency department if you have:

  • Worsening headache, drowsiness, confusion, weakness or vomiting after a head injury: call 112

This page is general information. It is not a diagnosis and does not replace a doctor who knows your history. Medfold keeps your records organised; it does not interpret them.

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