Anaesthetic risks and side effects

In modern anaesthesia serious problems are uncommon, however risk cannot be removed completely.

Modern equipment, training and drugs have made it a much safer procedure in recent years. To understand a risk, you must know:

  • How likely it is to happen
  • How serious it could be
  • How can it be treated

The risk to you as an individual will depend on:

  • Whether you have any other illness
  • Personal factors, such as smoking or being overweight
  • Surgery which is complicated, long or carried out as an emergency

Your anaesthetist or pre assessment nurse will discuss these risks with you at your appointments and in greater depth at your pre assessment appointment.

Will there be any side effects or complications?

You can work out the possibility of side effects and complications using the following scale and tables.

  • Very common (1 in 10)
  • Common (1 in 100)
  • Uncommon (1 in 1,000)
  • Rare (1 in 10,000)
  • Very rare (1 in 100,000)

Very common and common side effects which MAY occur

  General anaesthetic Regional anaesthetic
Feeling sick and vomiting after surgery Yes Yes
Sore throat Yes No
Dizziness, blurred vision Yes Yes
Headache Yes Yes
Itching Yes Yes
Aches, pains and backache Yes Yes
Pain during injection of drugs Yes Yes
Bruising and soreness Yes Yes
Confusion and memory loss Yes No


Rare and very rare complications which MAY occur

  General anaesthetic Regional anaesthetic
Damage to the eyes Yes No
Serious allergy to drugs Yes Yes
Nerve damage Yes Yes
Death Yes Yes
Equipment failure Yes Yes

Deaths caused by anaesthesia are very rare, and are usually caused by a combination of four or five complications together. There are about five deaths for every million anaesthetics in the UK. If you have any questions please speak to your doctor.

More information on the side effects and complications than is listed here is in the booklet Anaesthesia Explained, published by the Royal College of Anaesthetists.