A brain aneurysm is a bulge or ballooning in a blood vessel in the brain. Most are asymptomatic and never rupture—but when one does, it’s a life-threatening emergency (a ruptured aneurysm causes a type of stroke called a subarachnoid hemorrhage).

While many aneurysms go unnoticed until they rupture, some unruptured aneurysms can press on nearby structures, causing warning signs. And if one does rupture, symptoms come on suddenly and severely.

Here are 12 potential signs—some subtle, some dramatic—that should never be ignored.

🚨 Signs of a Ruptured Brain Aneurysm (Medical Emergency)
(Call 911 immediately if you or someone experiences these)

“The Worst Headache of My Life”
– Sudden, severe headache—often described as a “thunderclap”—peaking within seconds to minutes.
Nausea or Vomiting
– Accompanies the intense headache due to increased pressure in the brain.
Stiff Neck
– Caused by blood irritating the membranes around the brain (meninges).
Sudden Blurred or Double Vision– Blood or pressure affects cranial nerves controlling eye movement.
Seizure
– Unprovoked seizure with no prior history can signal bleeding in the brain.
Loss of Consciousness or Fainting
– May occur suddenly after the headache begins.
Confusion, Drowsiness, or Difficulty Waking Up
– Altered mental state due to brain irritation or swelling.Pain Above or Behind One Eye
– Persistent, localized pain that doesn’t respond to usual remedies.
Dilated Pupil in One Eye
– Pressure on the oculomotor nerve can cause one pupil to enlarge.
Numbness or Weakness on One Side of the Face– Nerve compression may affect facial sensation or movement.
Double or Blurred Vision (Gradual Onset)
– Unlike sudden vision changes in rupture, this may develop slowly.
Difficulty Speaking or Understanding Speech
– Rare, but possible if the aneurysm affects language centers.