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Wirral University Hospital NHS Foundation Trust

General Anaesthesia

If you are having a general anaesthetic, it will be given to you by an anaesthetist, either as a liquid that is injected into your veins through a cannula (a thin, plastic tube that feeds into a vein, usually on the back of your hand) or gas that you breathe in through a mask.
Your anaesthetist will stay with you throughout the procedure. They will make sure that you continue to receive the anaesthetic and that you stay asleep, in a controlled state of unconsciousness.

After the procedure, the anaesthetist will reverse the anaesthetic and you will gradually wake up.

General anaesthetic is essential for some surgical procedures where it may be safer or more comfortable for you to be unconscious. 

Side effects

General anaesthetic has some common side effects. Your anaesthetist should discuss these with you before your surgery. Most side effects occur immediately after your operation and do not last long. Possible side effects include:

  • Feeling sick or vomiting after surgery – about 33% of people feel sick after an operation. This usually occurs immediately after, although some people may continue to feel sick for up to a day
  • Shivering and feeling cold – about 25% of people experience this. Shivering may last for 20 to 30 minutes after your operation
  • Confusion and memory loss – this is more common in elderly people and is usually temporary
  • Chest infection – this can sometimes occur in people who have abdominal surgery and who smoke
  • Bladder problems – men may have difficulty passing urine and women may leak urine. This is more common after a spinal or epidural anaesthetic
  • Minor, temporary nerve damage – this affects around 1% of people and causes numbness, tingling or pain. It may get better in a few days or it may take several weeks to improve 
  • Dizziness – this can occur temporarily after your operation
  • Bruising and soreness – this can develop in the area where you were injected or had a drip inserted. It usually heals without treatment
  • Damage to teeth and mouth- During your operation, you may need to have a tube inserted down your throat to help you breathe. Afterwards, this causes a sore throat in about 40% of people. Around 5% of people may have small cuts to their lips or tongue from the tube. Around 1 in 4,500 people may have damage to their teeth.

Complications and risks

Some more serious complications are associated with general anaesthetics, but they are very rare (occurring in less than one case for every 10,000 anaesthetics given). Possible complications include:

  • Permanent nerve damage, causing paralysis or numbness
  • A serious allergic reaction to the anaesthetic or other drugs (anaphylaxis)
  • Death – this is very rare (there is approximately one death for every 100,000 general anaesthetics given)

Whether you are at any risk of these complications will depend on: 

  • Your medical history – whether you have any other illness
  • Personal factors – whether you smoke or are overweight, for example
  • Type of surgery needed – whether it is planned or carried out in an emergency, or whether it is a major or minor procedure
    Type of anaesthetic needed. General anaesthetics can have more side effects and complications than local anaesthetics.
    Your anaesthetist will discuss the risks with you before your operation. You may be advised to stop smoking or lose weight, if doing so could reduce your risk of developing complications. In most cases, the benefits of being pain-free during an operation outweigh the risks.