Fasting Guidelines
Fasting matters a great deal before your anaesthetic.
This is because anaesthesia often causes a loss of normal reflexes. This makes patients prone to regurgitation and inhalation of gastric contents.
The times you need to fast are
- 6 hours for food
- 4 hours for breast milk
- 2 hours for water
The time is based on when your surgery is booked to be performed.
Your surgeon or hospital will inform you what time you need to fast from when you book your surgery.
If you take a GLP-1 medication
GLP-1 medications are prescribed for diabetes and for weight loss. They include Ozempic and Wegovy (semaglutide), Saxenda and Victoza (liraglutide), Trulicity (dulaglutide), and Mounjaro (tirzepatide).
These medicines slow the rate at which your stomach empties, so the fasting times above are not enough on their own. Your stomach may still hold food or drink at the time of your anaesthetic, which is unsafe. Preparation needs to start the day before your procedure.
Please tell your anaesthetist that you take one of these medicines. Keep taking it as you normally would — it does not need to be stopped before surgery.
The day before your procedure
- No solid food for the whole day.
- Clear fluids only. Clear fluids are drinks you can see through: water, black tea or black coffee, apple juice, lemonade, clear broth, jelly, icy poles, electrolyte sports drinks, and the pre-surgery carbohydrate drinks some hospitals supply.
- Avoid anything that is not clear: milk or milk-containing drinks, yoghurt drinks, ice cream, orange or prune juice, fibre supplements such as Benefiber or Metamucil, and alcohol.
The day of your procedure
Do not eat any solid food. Unless your hospital tells you otherwise:
- Morning procedure — stop all clear fluids except water at midnight. From when you wake, you may drink small amounts of water each hour, up to half a cup (125 ml), until 6am. Stop all drinks from 6am.
- Afternoon procedure — stop all clear fluids except water at 6am. From when you wake, you may drink small amounts of water each hour, up to half a cup (125 ml), until 11am. Stop all drinks from 11am.
Limited-fasting regimens such as SipTilSend, where patients drink water freely until they are called for surgery, are not appropriate if you take one of these medicines.
If you have diabetes — particularly if you take insulin — or you are having bowel preparation for a colonoscopy or barium enema, please ask your doctor for instructions specific to you.
If you think you have not followed these instructions correctly, your procedure may still be able to go ahead. Start following the instructions from wherever you are in the timeline, and contact your hospital or anaesthetist as soon as you can to tell them when you began fasting. That information matters for your safety.
There is more detail in ANZCA’s patient information sheet, Preparing for your medical procedure when taking some diabetes and/or weight loss medications (PDF, 430 KB). ANZCA also maintains a page on GLP-1 medications and anaesthesia with the current version of this advice.
If you have any queries regarding your fasting please contact us.
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