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Health A to Z: Brain aneurysm

Find out what a brain aneurysm is, what the symptoms are, when to get medical help, how it's treated and what you can do to help stop an aneurysm bursting.

Most brain aneurysms are small and do not cause symptoms. They're often found during a test for another condition.

If you have a larger aneurysm, you may get symptoms such as:

  • a headache
  • pain above or around your eye
  • changes in your vision, such as double vision
  • dizziness and balance problems
  • numbness or weakness on 1 side of your face
  • difficulty concentrating and speaking
  • problems with your short-term memory

If a brain aneurysm bursts, it can cause a bleed on your brain called a subarachnoid haemorrhage.

The main symptom is a sudden, severe headache that's sometimes described as a "thunderclap headache".

Call 999 if:

You or someone else suddenly get:

  • a headache that's extremely painful and does not go away
  • weakness in the face – 1 side of the face may droop (fall) and it might be hard to smile
  • weakness or numbness in 1 arm or down 1 side of the body – it may not be possible to lift both arms fully and keep them there
  • speech problems, such as slurring words, sounding confused, or finding it difficult to speak or find the right words
  • blurred vision or loss of sight in 1 or both eyes

Do not drive yourself to A&E.

The person you speak to at 999 will give you advice about what to do.

Ask for an urgent GP appointment or get help from NHS 111 if:

  • you keep getting headaches, they do not go away or they're getting worse
  • you have pain above or around your eye
  • you have any other symptoms of a brain aneurysm that do not go away

You can call 111 or get help from 111 online.

Treatment is not usually needed for small brain aneurysms that are not causing symptoms. This is because they often do not get bigger and have a low risk of bursting.

You may just need regular follow-up scans to check if it’s getting bigger.

Brain aneurysm surgery

If there’s a risk of the aneurysm bursting, or if it’s already burst, surgery will usually be needed.

The 2 main types of surgery are:

  • surgical clipping – where a small metal clip is attached to the blood vessel in the brain to stop blood flowing into the aneurysm
  • endovascular surgery – where a coil or small piece of wire mesh is put inside the aneurysm to slow the flow of blood into it and help a blood clot to form

If possible, your surgeon will talk to you about the procedure they feel is most suitable for you and discuss any risks involved.

General anaesthetic is used for both surgical clipping and endovascular surgery, so you’ll be asleep and unable to feel any pain or discomfort during the procedure.

Find out more

It's not always clear what causes brain aneurysms.

But things that increase your chances of getting a brain aneurysm include:

If you have a brain aneurysm there are some things you can do to reduce the risk of it getting bigger and bursting.

Do

Don't

  • do not drink too much alcohol

  • do not take illegal drugs

Driving

You may not be allowed to drive if you have a brain aneurysm. Your doctor will be able to advise you about whether it’s safe for you to drive and if you need to tell the DVLA.

Find out more

Finding out you have a brain aneurysm can be scary and worrying.

As well as getting help and advice from your doctor, you may find it helpful to talk to other people with the condition, either at a local support group or online.

Headway

Information, help and support for anyone affected by brain injury.

Brain and Spine Foundation

Information and support for anyone affected by brain conditions, including brain aneurysm.

Content supplied by the NHS website

Page last reviewed: 10/10/2025