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Auckland DHB Anaesthesia

Public Service, Anaesthesia

Risks of Anaesthesia

Common unwanted side effects

  • Nausea and/or vomiting - this is a common side effect which may be due to the surgical process or anaesthesia. If you have previously had nausea or vomiting, please inform your anaesthetist as there are various ways of addressing this problem. 
  • Headache - There are many different causes for this ranging from not having had your normal morning coffee; to being thirsty and not having enough liquid to drink.  After a spinal or epidural anaesthetic there is a risk of developing a "post-dural puncture headache" which will need anaesthetic input to diagnose and treat.
  • Sore or dry throat or lips - this is because of the dryness of the anaesthetic gases, including the oxygen you need to be given.  Breathing tubes placed past your throat while under general anaesthetic can also contribute. It is often worse if you have even a mild cold, and will usually respond well to having small sips of cold water.
  • Pain and/or bruising can occur at injection sites as we need to use a needle to insert our cannulas. 
  • Tingling and numbness in a part of your body that was given local anaesthetic.  After spinal/epidural or nerve blocks it is reasonably common to have "pins and needles" or areas of numbness as the nerves recover from the local anaesthetic.  The vast majority of these feelings will have gone totally by six months after the surgery.

Less common unwanted side effects

  • Muscle aches and pains - these can be caused by having the surgery, having to lie still for the length of the surgery or even by our anaesthetic medications.
  • Weakness - this is often a reflection of your body recovering from the surgical process.
  • Mild allergic reaction - itching or a rash.  The itching may well be a side effect of the medication we give you to make you comfortable from a pain point of view.

Uncommon unwanted side effects

  • Awareness under general anaesthetic - being paralysed but awake during surgery. Anaesthetists always try very hard not to have this happen, and with modern monitoring equipment it now happens exceedingly rarely.  If you have any concerns please mention them to your anaesthetist.
  • Damage to teeth, dental prosthetics and lips - again we try very hard to not have this happen but when we put in the breathing tube every patient is different and damage may occur.
  • Damage to the voice box and chords causing temporary loss of voice.
  • Allergic reactions - if you are aware of medications that you have reacted to in the past, please make us aware of this.  Even if you have told other people who are caring for you, this is the type of information that cannot be repeated too often.  If an allergic reaction occurs during your anaesthetic, your anaesthetist is taught how to handle this and after you recover they will refer you to an allergy testing clinic to ensure we identify the medication that you must never have again.
  • Blood clots in the leg - much like the ones developing during long airline journeys. 
  • Damage to nerves, pressure areas and even paralysis - we do protect you to prevent these but they can still happen after a regional or a general anaesthetic. 

Very rare and infrequent events that may cause death or paralysis

  • Severe allergy and shock
  • Very high temperature as a result of a genetic reaction to our anaesthetic
  • Stroke or heart attack
  • Vomit in the lungs
  • Blood clots in the lungs
  • Blood clots in the back
  • Brain injury
  • Nerve injury that is permanent.

We strive to avoid all untoward events, and we are also trained in managing untoward events, so that if anything does happen it is the anaesthetist that will manage them and guide you through the recovery process.  Please feel free to contact the Anaesthetic Department if you are at all concerned after you have had an anaesthetic.

The risks of anaesthesia are increased by or in:

  • Elderly patients
  • Bad cold or flu, asthma or other chest disease - the risk of this extends for about 6 weeks after the event
  • Smoking
  • Obesity
  • Diabetes
  • Heart disease
  • Kidney disease
  • High blood pressure
  • Other medical conditions.

This page was last updated at 9:54AM on November 24, 2021.