Find out about general anaesthetic, a type of anaesthesia that is used to provide pain relief during surgery, including side effects and risks.
General anaesthetic is a type of anaesthesia. This is medication that causes loss of sensation. It is used to give pain relief during surgery.
General anaesthetic makes you completely lose consciousness so that surgery can be carried out without causing any pain or discomfort.
How anaesthetic works
Anaesthetic works by blocking the signals that pass along your nerves to your brain. Nerves are bundles of fibres that use chemical and electrical signals to pass information around your body.
General anaesthetic stops your brain recognising the signals coming from your nerves so that you cannot feel anything.
How general anaesthetic is given
An anaesthetist is a doctor who has been specially trained in 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)
- 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.
When general anaesthetic is used
General anaesthetic is essential for some surgical procedures where it may be safer or more comfortable for you to be unconscious. It is usually used for long operations or those that may be very painful. Examples include:
- surgery to remove the gallbladder (laparoscopic cholecystectomy) – the gallbladder is a small, pear-shaped pouch in the upper part of the abdomen
- hernia repair – surgery to repair a weakness or split in the muscle wall where an organ has pushed through
- liposuction – an operation to remove excess body fat
- hysterectomy – an operation to remove a woman’s womb
If you need to have a general anaesthetic, you will meet your anaesthetist and plan your anaesthetic together before surgery.
Your anaesthetist will look at your medical history and will ask you whether anyone in your family has had problems with anaesthesia. They will also ask you about your general health and lifestyle, including whether you:
- have any allergies
- smoke or drink alcohol
- are taking any other medication
Your anaesthetist will also be able to answer any questions you have. Let them know if you're unsure about any part of the procedure or if you have any worries or concerns. You should be given clear instructions to follow before the operation, including whether you can eat anything in the hours leading up to it.
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 and 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. It will make you feel feverish (hot and cold) and cause breathing difficulties.
- 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 after your operation. You will be given fluids to treat it.
- Bruising and soreness – this can develop in the area where you were injected or had a drip fitted. It usually heals without treatment.
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.
It is possible for a patient to wake during surgery and experience pain, although this is very rare. The chance of it happening has been greatly reduced by using monitors to measure the amount of anaesthetic being given.
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 (anaphylaxis)
- death – this is very rare (there is approximately one death for every 100,000 general anaesthetics given)
Complications are more likely to occur if you:
- are having major surgery or emergency surgery
- have any other illnesses
- are overweight
In most cases, the benefits of being pain-free during an operation outweigh the risks.