Cerebral oedema: quick guide to causes, signs and what to do

Cerebral oedema can happen after an injury, infection, stroke, or certain medicines. When fluid collects in brain tissue or in the spaces around it, pressure inside the skull rises, squeezing brain cells. That pressure causes headaches, nausea, confusion, trouble walking, seizures or loss of consciousness. Knowing the causes and emergency signs helps you act fast and save brain tissue.

Causes vary but the ones to watch are traumatic brain injury, large strokes, brain infections like meningitis or encephalitis, high altitude illness, tumor-related swelling, and reactions to some drugs. Sometimes metabolic problems such as low sodium cause swelling. Doctors sort the type of oedema by imaging—pattern matters and directs treatment.

If you see sudden severe headache, repeated vomiting, new weakness on one side, drooping of the face, trouble speaking, or a drowsy person, treat it as an emergency. Call emergency services.

Paramedics and hospital teams focus on stabilizing breathing and blood pressure and quickly reduce intracranial pressure with oxygen, head elevation, and medications. Medical treatment can include diuretics like mannitol, hypertonic saline, steroids in specific tumor or inflammatory cases, and anti-seizure drugs if needed. In severe cases surgeons may place an external ventricular drain or do a decompressive craniectomy to relieve pressure. Each option has risks and benefits, so doctors pick what fits the cause and the patient’s condition.

At home, prevention matters. Wear helmets for bike or motorcycle rides, manage high blood pressure, treat infections early, and follow altitude advice when trekking. Don’t stop or start powerful medicines on your own—some drugs can trigger swelling or make it worse.

Tests doctors use include CT scans, MRIs, blood sodium levels, and sometimes lumbar puncture after imaging rules out dangerous pressure. Imaging shows where the fluid is and whether midline brain structures have shifted. That shift is a key sign of dangerous pressure that needs fast action.

If you or someone close has a history of brain injury or stroke, learn the personal baseline for alertness and behavior. Subtle changes—slower thinking, worse balance, or new headaches—are worth calling your healthcare provider. Treatment outcomes are better when swelling is caught early and the underlying cause is treated fast.

Some medications mentioned on our site relate to brain swelling care—diuretics, steroids, anticonvulsants, and blood-pressure medicines. Read specific articles for dosing, side effects, and interactions before you change any treatment. If you are caring for someone after a head injury, keep a written log of symptoms, sleepiness levels, and any vomiting episodes to share with emergency staff. For hikers or travelers going to high altitude, plan acclimatization days and carry a portable pulse oximeter if you have heart or lung conditions. When in doubt, call.

Browse related articles on symptom recognition, when to seek emergency care, and how common treatments work so you can have clear questions for your clinician.