This information is aimed at adult patients expecting to have an operation or procedure requiring an anaesthetic.

An anaesthetic is given by a specially trained doctor called an anaesthetist.

There are different types of anaesthetics and the type chosen depends on the type of operation, your physical condition and your preferences.

Together, you and your anaesthetist will plan your anaesthetic.

Types of anaesthetic include:

  • Local Anaesthetic: An injection numbs a specific part of the body, e.g. eye numbed for cataract surgery.
  • Regional Anaesthetic: An injection numbs a larger part or area of the body, e.g. a spinal anaesthetic numbs lower body for caesarean section.
  • General Anaesthetic: Anaesthetic medication produces a controlled unconsciousness. You are asleep and will feel nothing.

What are the Risks involved?

Modern anaesthesia is very safe and serious problems are uncommon.

However, risk cannot be removed completely.

The likelihood of complications will depend on your medical condition, the type of surgery planned and the anaesthetic used.

Specific risks associated with your operation and anaesthetic will be discussed with you before your operation.

To understand the risk fully, you need to know:

  • how likely it is to happen
  • how serious it could be
  • how it can be treated if it happens

The risk should be weighed up against the benefit of the operation.

Only you can decide how much this risk affects your plan to have the operation.

Anaesthetic risks can be described as side effects or complications:

  • Side effects: are expected but unwanted consequences of a treatment. We know in advance that side effects can happen and often steps can be taken to prevent them, e.g. feeling sick after a general anaesthetic.
  • Complications: are unexpected unwanted events due to a treatment. Anaesthetists are trained to prevent complications and treat them when they happen, e.g. severe allergy to an anaesthetic drug.

The following list shows the risk of side effects and complications associated with anaesthesia:

Very Common to Common Side Effects (happens to 1 in 10 to 1 in 100 patients)

  • Nausea and vomiting
    • Anti-sickness drugs are given routinely but some operations and medicines are more likely to cause sickness than others.
  • Sore throat
    • A breathing tube is used for most general anaesthetics. This can cause a sore throat lasting up to a few days.
  • Dizziness and feeling faint
    • Anaesthetics can cause low blood pressure which may make you feel dizzy or faint. This can be treated with drugs and fluids.
  • Damage to lips or tongue
    • Minor damage to lips or tongue is common.
  • Shivering
    • Care is taken to keep you warm before, during and after your operation, however shivering can be a side effect of anaesthetic drugs.
  • Headache
    • Dehydration, anxiety, and the operation itself may cause a headache that should resolve with time and simple pain relief.
    • A special type of severe headache can happen after spinal or epidural anaesthetic. These are managed by the anaesthetist and may require a further procedure.
  • Itching
    • This can be caused by allergy but is a common side effect of many strong pain relief medicines such as morphine.
  • Aches, pains and backache
    • During your operation, you may lie in the same position for a long time. You are positioned with care to prevent discomfort.
    • Sometimes, anaesthetic drugs can cause muscle aches.
  • Bruising and soreness around injection site
    • Bruising may occur around the site of the drip into the vein. Some medicines can also be sore at the time of injection.
  • Confusion and Memory Loss
    • This is more common in older adults after a general anaesthetic and may be due to several causes. Your anaesthetist can discuss this with you if there are any concerns about this.
  • Bladder problems
    • After many types of operation, you may experience difficulty in passing urine. This may require treatment with a urinary catheter. Most bladder problems recover before leaving hospital.
  • Chest infection
    • More likely to occur if you smoke, or if you already have breathing problems. This can cause breathing difficulties after your operation and prolong your hospital stay to treat. This is why we advise you to give up smoking for as long as possible before your anaesthetic.

Uncommon Side Effects (happens to 1 in 1000 patients)

  • Damage to teeth, lips or tongue
    • May occur as your anaesthetist is inserting the breathing tube. It is more likely if you have weak teeth, a small mouth, or a stiff neck.
  • Breathing Difficulties
    • After the operation, your breathing can be more difficult due to strong pain relief medicines and some anaesthetic medicines. This can be treated with other medicines while you are in the recovery room.
  • Existing medical conditions getting worse
    • There is slightly increased risk that your medical conditions worsen around the time of surgery. This includes conditions such as heart disease, stroke, and diabetes. It is important to have you as fit as possible before your surgery. Your anaesthetist will try to ensure that your conditions are well treated before, during and after surgery.

Rare or Very Rare Side Effects (happens to 1 in 10, 000 to 1 in 100, 000 patients)

  • Damage to eyes
    • Great care is taken to protect your eyes. It is possible for the surface of the eye to become damaged during surgery due to contact, pressure or exposure. This is usually temporary and treatable. Serious and permanent loss of vision is possible but very rare.
  • Nerve damage
    • The risk of this varies with the type of anaeasthetic. It can occur due to pressure on a nerve during an operation, or caused by a needle during regional anaesthesia (a nerve block). It can result in a weakness or numbness that is usually temporary. Very rarely this can be permanent.
  • Awareness
    • This is when you become conscious during a general anaesthetic. It happens when not enough anaesthetic has been given. Monitors are used routinely to measure the amount of anaesthetic you are receiving, and how your body is responding to it. This allows your anaesthetist to give you enough anaesthetic to keep you unconscious.
  • Serious allergy to medicine
    • Almost any drug can cause an allergic reaction. Anaesthetists are trained to treat allergy but very rarely people can die due to a severe reaction. Tell your anaesthetist about any history of allergy.
  • Equipment failure
    • Equipment is tested regularly and monitors are used routinely to give immediate warning if there is a problem. Back-up equipment is available quickly if required.
  • Brain damage and death
    • These are extremely rare and are caused by combination of unexpected complications happening at the same time. There are about 5 deaths for every 1 million anaesthetics given in the UK.

You can find more information related to your anaesthetic on Royal College of Anaesthetists website.