General Anaesthetic: What to Expect, Common Side Effects and Real Risks

For many people, the anaesthetic worries them more than the operation itself. Modern anaesthesia is very safe, and knowing exactly what happens can take much of the fear away.

Imagine lying on a trolley outside the operating theatre, heart racing, wondering whether you will wake up, or worse, wake up during the operation. The anaesthetist sits down, explains everything calmly and holds your hand as you drift off.

What a general anaesthetic is

A general anaesthetic is a combination of medicines that puts you into a controlled state of unconsciousness, so you feel no pain and have no awareness during surgery. It is given and monitored throughout by an anaesthetist, a healthcare provider specialising in anaesthesia, sometimes supported by an anaesthesia associate or nurse anaesthetist depending on the country.,It is different from sedation, where you are relaxed and drowsy but not fully unconscious, and from regional anaesthesia, such as a spinal or nerve block, where part of the body is numbed while you stay awake.

Meeting the anaesthetist

Before your operation, you will usually meet the anaesthetist, who will ask about your health, previous anaesthetics, allergies, teeth, medicines and any problems in your family with anaesthetics. This is a good time to ask questions and to mention anxiety, sickness after previous operations or any preferences.

How you go to sleep

In the anaesthetic room or operating theatre, monitors are attached to check your heart, blood pressure and oxygen levels. Most adults have the anaesthetic given through a cannula, a thin tube in the back of the hand or arm. You may feel a cold sensation as the medicine goes in, and you usually fall asleep within a minute.,Some people, especially children, go to sleep by breathing anaesthetic gas through a mask. Once you are asleep, a breathing tube or device is usually placed to keep your airway safe.

During the operation

Throughout the operation, the anaesthetist stays with you, continuously monitoring your heart rate, blood pressure, oxygen levels, breathing and depth of anaesthesia, and giving fluids, pain relief and other medicines as needed. When the operation ends, the anaesthetic is stopped and you wake up, usually in a recovery area where specially trained staff look after you.

Common side effects

• Feeling sick or vomiting, which can be reduced with anti-sickness medicines; tell the team if you have had this before
• Sore throat from the breathing tube
• Shivering and feeling cold
• Drowsiness and feeling muddled for a few hours
• Aches and pains
• Older adults can be confused for longer, sometimes days (post-operative delirium)

Serious risks

Serious complications from anaesthesia are rare. They include severe allergic reactions, damage to teeth, breathing problems, and very rarely awareness during anaesthesia or death. The risk of death directly caused by anaesthesia in healthy people having routine surgery is very low; it is more likely to be linked to serious illness or emergency surgery.,Your anaesthetist will explain the risks that apply to you, which depend on your health, age and the type of operation.

Awareness under anaesthesia

Many people fear waking up during surgery. Accidental awareness is rare, estimated in large UK studies at around 1 in 20,000 general anaesthetics, though it is more likely in certain situations such as emergency caesarean sections or heart surgery. Anaesthetists use careful monitoring to prevent it. If you have any memories of your operation, tell the team so they can support you.

The first 24 hours after a general anaesthetic

• Have a responsible adult take you home and stay with you overnight
• Do not drive, cycle or operate machinery
• Do not drink alcohol
• Do not sign legal documents or make important decisions
• Rest, eat light meals and drink fluids
• Take pain relief as advised

Reducing anxiety

• Ask your questions before the day of surgery
• Tell the team you are anxious; they are used to helping
• Bring headphones and music for the waiting time if allowed
• Practise slow breathing
• Ask whether a relative can stay with you until you go into the anaesthetic room, particularly for children

Frequently asked questions

Will I dream?

Some people remember dreaming, but most remember nothing between going to sleep and waking up.

Can I keep my dentures in?

You will usually be asked to remove them before the anaesthetic.

Is it safe to have an anaesthetic if I am overweight?

Yes, but it may carry slightly more risk. Your anaesthetist will plan accordingly.

But what if I do not wake up?

For most people, the chance of a serious problem is very small. Anaesthetists are trained to monitor you constantly and to manage problems quickly. Talk to them about your specific risks.

Related: Pre-operative assessment

Sources: Royal College of Anaesthetists, 5th National Audit Project (NAP5) on accidental awareness, American Society of Anesthesiologists, World Federation of Societies of Anaesthesiologists.