Fasting For Your Operation

Mr and Mrs Gas Home

Most of us enjoy our food and coffees ( your anaesthetists included), so fasting is never much fun. However there are good reasons why we require you or your child to fast before your operation.

As you go off to sleep, the initial part of your anaesthetic we call “induction”, there is a chance that as your stomach muscles relax you could either vomit or regurgitate some of the fluid from your stomach into your throat. Even more rarely some of this fluid can go down into your lungs, something we call “aspiration”. This can cause a variety of serious lung complications ranging from a bit of a cough and fever all the way through to a severe lung infection.  Your stomach contents are highly acidic and will damage the delicate lung tissues.

If you happen to have a full stomach; you are both more likely to vomit or regurgitate during induction and if any of the vomit was to go into the lungs it would be more likely to cause complications. This is why we ask you to fast before your surgery

You are probably thinking “what happens when someone has just eaten and is then involved in some sort of accident that requires surgery?” This is not an uncommon occurrence at all and in these cases we weigh up the risks of doing the emergency surgery with a full stomach, and the risk of waiting until the patient is fasted. These decisions are individualised for every case we do and in some cases we operate on a patient with a full stomach as this is in the patient’s best interest. We can use special manouevres to reduce the risk of aspiration, but the preference and safest option is always for a person to be properly fasted.

In elective surgery we always try to minimise any risks of complications occurring so this is why we ask you or your child to fast for your surgery.


  1. Solid food including milk  and baby formulae six hours fasting.
  2. Clear fluids ( eg apple juice, black coffee or tea ie no milk ) and breast milk four hours fasting.
  3. Water only one hour fasting.
  4. Lollies and chewing gum count as food as the act of chewing triggers your stomach to start producing acid.

In terms of what to eat, if you have been told to fast from midnight the night before your morning surgery then you may have a normal meal the night before. I would not advise going out to Pizza hut and eating five pizzas ! but a normal healthy meal is fine. For breakfast before an afternoon operation it is fine to have cereal, fruit and toast. Poached or boiled eggs are also a good idea, again however McDonalds or Bacon and eggs should sensibly be avoided. A big fatty meal takes your stomach much longer to digest.

We would encourange you to continue drinking plenty of water up until the time you arrive at the hospital as this will lessen the chances of you feeling dehydrated or nauseous. You do not need to take “sips only” as people are commonly told over the phone, a proper drink of water is fine.   It is much easier to get an IV into a warm, well hydrated person!