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Subarachnoid Haemorrhage
A subarachnoid haemorrhage is bleeding into the space around the brain, most often from a burst aneurysm. It causes a sudden, severe headache and is a medical emergency.
Causes & risk factors
- A burst brain aneurysm (most common)
- Head injury
- Abnormal blood vessels
- High blood pressure
- Blood-thinning medicines or clotting problems
Common symptoms
- Sudden, severe "thunderclap" headache
- Stiff neck
- Nausea and vomiting
- Sensitivity to light
- Loss of consciousness
- Confusion or weakness
Tests & diagnosis
- CT scan of the brain (urgent)
- Lumbar puncture (if CT is normal but suspicion remains)
- CT or MR angiography
Treatment & management
- Emergency hospital admission, often to intensive care
- Procedures to seal the source of bleeding (coiling or clipping)
- Controlling blood pressure
- Medicines to reduce blood-vessel spasm
- Close monitoring and rehabilitation
When to see a doctor urgently
- A sudden, severe headache that peaks within seconds — call your local emergency number now
- Headache with collapse, vomiting, stiff neck or seizures — call your local emergency number now
- Sudden weakness, confusion or loss of consciousness
- The worst headache of your life — do not wait
Frequently asked questions
How quickly do I need help?
Immediately. A subarachnoid haemorrhage is an emergency where fast treatment saves lives and reduces complications. Call your local emergency number at the first sudden severe headache.
What causes it?
The most common cause is a burst aneurysm, but head injury and abnormal blood vessels can also be responsible. Scans in hospital identify the source.
Explore more
Sources & further reading
- World Health Organization (WHO)
- MedlinePlus — U.S. National Library of Medicine
- Ministry of Health & Family Welfare, India
- Indian Council of Medical Research (ICMR)
Reviewed by Dr. Sanjay Anbu, MBBS. MedDroid is an AI medical assistant and can make mistakes. It provides general health information, not a diagnosis or medical advice — always consult a qualified clinician. In an emergency, contact your local emergency number immediately.