Anaesthesia complications: side effects, risks and what to do afterwards

NHS inform describes two types used often: local anaesthetic, where you stay awake but a small area is numbed, and general anaesthetic, where you are fully unconscious and unaware of the procedure. Other types include regional anaesthetic, which numbs a specific area, epidural and spinal anaesthesia, which numb the lower half of the body, and sedation, which makes you sleepy and relaxed. Different types can be combined, for example a regional anaesthetic with a general anaesthetic to relieve pain after an operation.

The NHS says a general anaesthetic is used when other types are not suitable. The type recommended depends on the procedure and on what is best for you, and the anaesthetist, a doctor with specialist training in anaesthesia, will discuss options and risks with you before the procedure.

After a general anaesthetic the NHS lists feeling thirsty, drowsy, a hoarse voice or sore throat from the breathing tube, shivering, feeling or being sick, pain, bruising or soreness from the injection or from lying still, and feeling confused or having memory loss. These usually settle within minutes or hours, and medicines can help with pain or sickness.

NHS inform lists common side effects of anaesthetics more broadly, including feeling sick, vomiting, dizziness, feeling faint, shivering, headache, itchiness, bruising, soreness, difficulty peeing and aches and pains. It says they do not usually last long and that some can be treated, so tell staff if you have them.

For local anaesthetic the NHS lists discomfort when the injection is given, minor bruising or soreness, a tingling or burning sensation as it wears off, headaches, dizziness or blurred vision, twitching muscles or shivering, and continuing numbness, weakness or pins and needles. These usually get better within minutes or hours.

The NHS lists possible complications of a general anaesthetic as a serious allergic reaction, breathing difficulties, a chest infection, damage to the teeth or mouth from the breathing tube, damage to the eyes, nerve damage causing numbness, tingling or weakness, and longer-lasting confusion, particularly in older people. It stresses that these are rare, and that your care team will check for complications and treat them.

NHS inform describes very rare complications of anaesthetics as permanent nerve damage, which can cause numbness or paralysis, and an allergic reaction to an anaesthetic medicine (anaphylaxis). It says that as with any surgery or medical procedure there is a rare risk of complications, which is weighed against the benefits and explained before the operation. For local anaesthetic, the NHS says more serious side effects such as a severe allergic reaction are rare and usually happen within a few minutes, and the doctor giving it is trained to treat them.

NHS inform says your risk of complications depends on many factors: your medical history and any other serious conditions, personal factors such as whether you smoke or are overweight, the type of procedure, whether it is planned or an emergency, and the type of anaesthetic. Your anaesthetist will explain any particular risks before the procedure, and in most cases the benefits outweigh the risks.

The NHS says that if your procedure is planned you can help your recovery by making sure long-term conditions such as diabetes, high blood pressure or anaemia are managed as well as possible, keeping physically active, stopping smoking and getting treatment for dental problems to reduce the risk of tooth damage from the breathing tube. At the pre-operative assessment you may have blood tests, an X-ray, an ECG or a fitness test. Tell the team about any medicines you take, any health conditions, any previous allergic reaction to an anaesthetic or other medicine, and any worries such as a fear of needles.

The NHS says you will feel drowsy at first, may have an oxygen mask, and that staff will give medicines for pain or nausea. Effects can last around 24 hours. For at least 24 hours you are advised to have someone stay with you, not to drive or ride a bike, not to cook or use machinery, not to look after children or others alone, not to smoke or drink alcohol and not to make important decisions because judgement may be affected.

Someone will need to take you home by car or taxi. The NHS also advises being careful about posting on social media as you may not be thinking clearly. For a local or regional anaesthetic, it advises moving carefully until the anaesthetic wears off and getting someone to drive you home.

The NHS says to ask for an urgent GP appointment or get help from NHS 111 if you have recently had a general anaesthetic and are worried about side effects or they do not get better. The same advice applies after a local anaesthetic. The hospital that treated you can also be contacted if you have concerns after you go home. If you have difficulty breathing, severe pain, a spreading rash or swelling of the face and throat, treat it as an emergency and call 999.

If you think something went wrong, it is reasonable to ask the team that treated you to explain what happened. If you have long-lasting numbness, weakness, memory problems or other symptoms after anaesthesia, mention them to your GP or surgical team so they can be assessed.

Anaesthesia is provided by an anaesthetist whether you are treated on the NHS or privately, and the pre-operative assessment, consent discussion and recovery follow similar principles. Private care often allows a choice of surgeon and sometimes more time for the pre-assessment, but the same questions are useful in either setting: which anaesthetic is planned, what the risks are for you and who to contact afterwards.