Frequently asked questions about fasting guidelines for adults

What can I eat and drink the night before and day of my surgery?


  • No food for eight hours before your surgery (even food or formula given through a feeding tube)
  • Up to two hours before your surgery, you may drink clear fluids if your doctor approves. Clear fluids are:
    • Water
    • Apple or white grape juice
    • Carbonated drinks, such as soda pop
    • Sports drinks such as Gatorade®
    • Clear tea
    • Black coffee
  • No milk, creamer, or lemon added to any drinks
  • No alcohol
  • Do not eat or drink two hours before surgery.


Your stomach must be empty for surgery. We do not want food from your stomach to get into your lungs during surgery. Your surgery will be delayed if you do not or cannot follow these instructions.

Why can’t I eat or drink before my surgery?

Our protective reflexes slow down when we are given anesthesia. One protective reflex is to keep stomach contents from going into our airway. Aspiration can happen when stomach contents enter our airway. This is less likely to happen when your stomach is empty. Fasting (not eating or drinking) keeps your stomach empty.

Why is aspiration so bad?

Solid or semi-solid stomach contents may not let your lungs get air. Liquid stomach contents that are acidic may burn your lungs and stop you from getting air. Both types of aspiration may cause brain damage or death.

Aspiration can be treated. Most people survive, but treatment in an intensive care unit (ICU) is often needed. Aspiration may lengthen your hospital stay by days to weeks.

Can I chew gum or suck on hard candy while waiting for my surgery?

Adults (18 years and older) can chew gum or suck hard candy until their surgery. Surgery should not be cancelled or delayed because a person is chewing gum or sucking hard candy. Do not swallow gum or hard candy. It will count as a meal, and you will need eight hours of fasting before your surgery.

When should I stop chewing tobacco or putting snuff in my mouth before my surgery?

Stop chewing tobacco or snuff six hours before your surgery.

I was in an automobile accident and need emergency surgery. I ate just before the accident and it has only been four hours. My doctor says I need the surgery now. Why do I not have to wait eight hours?

Guidelines help doctors and patients decide about health care. Fasting guidelines are not meant to be the final decision. The risk of aspiration must be weighed against the risk of not having surgery in a timely manner. Your anesthesiologist may change the type of anesthesia to lower your risk.

If I take food in through an enteral or nasogastric tube (gastric/stomach tube, enteral/jejunostomy tube), should I follow the same fasting instructions?

Fasting for eight hours after feeding is preferred. For people who have residual volumes checked, four hours fasting after the last feeding is safe if residual volumes are not going up. Feeding should be stopped at the first sign of higher stomach residual volumes. Continuous duodenal feedings have less risk of aspiration than stomach feedings. The urgency of the surgery and the need for continuous nutritional support versus the higher risk of aspiration needs to be considered by the patient and all the health care providers involved in the care.

Why can I only use apple jelly to take crushed medicines?

Apple jelly is made from apple juice that has been boiled and cooled causing it to thicken. Apple juice is an approved clear fluid. Plain apple jelly can be eaten up to two hours before surgery. On your day of surgery, apple jelly may be used to take crushed medicine. Do not use pudding or apple sauce.

Who came up with the fasting guidelines?

They are based on medical research and expert opinion. The American Society of Anesthesiologists and the European Society of Anesthesiologists each have task forces to make them. Faculty in the Department of Anesthesia at the University of Iowa adapts these guidelines for University of Iowa Hospitals & Clinics.

Last reviewed: 
June 2017

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