Why Can't I Eat Before Surgery?

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Question: Why Can't I Eat Before Surgery?

Rest assured that your doctor is not out to torture you, this is why it is so important not to eat before surgery.


The drugs used for anesthesia are so powerful that they slow or stop your respiratory drive. When you are under general anesthesia a breathing tube is inserted through your mouth and into your airway, (trachea), to help you breathe. The trachea and the esophagus open at nearly the same place in the back of the throat.

Under normal conditions a small flap of tissue covers the trachea when we swallow preventing the inhalation of food into the lungs. When you are under general anesthesia this defense mechanism is compromised and contents from the stomach can come up through the esophagus and be inhaled into the lungs. You are also at increased risk of vomiting. These two things can lead to a very dangerous condition called aspiration pneumonia. Aspiration is not only a risk of general anesthesia but also regional anesthesia with any kind of sedation.

The best way to prevent this is to make certain that there is nothing in your stomach that could be inhaled into the lungs. Even small amounts of liquids are dangerous. Smoking, chewing gum, sucking on a mint, or brushing your teeth can cause your stomach to create digestion fluids which can also be inhaled into the lungs. Therefore, it is very important that you follow your doctor or nurses instructions about not eating prior to surgery.

Most hospitals recommend that you go without solid foods for a period of at least 6-8 hours and that you stop drinking clear liquids at least two hours before your procedure. To simplify some hospitals or surgical centers simply tell all of their patients to stop eating and drinking after midnight before their surgery.

Some individuals may have medical conditions that prevent them from fasting or going without liquids for the usual period of time necessary prior to surgery. If you have a medical condition that interferes with your ability to go without food or drink, notify your doctor ahead of time so that special arrangements can be made ahead of time. You may need to go to the hospital or surgical center early for the administration of IV fluids or glucose. The hospital may also arrange for you to have your procedure first thing in the morning. Diabetics may be instructed to skip their morning medication so that their blood sugar does not drop too low before surgery.

If you have an infant that depends on formula or breast milk follow the instructions carefully for when to stop giving them formula or breast milk. Formula is usually considered a solid food and should be stopped at least six hours before the procedure. Breast milk, however, is thought to be metabolized more rapidly than formula and some doctors recommend it be stopped only four hours before surgery.

Most hospitals or surgical centers make an effort to schedule infants and small children first thing in the morning so that they are not forced to go without food or drink any longer than necessary.


NHS Choices. Can I eat or drink before an operation? Accessed: March 31, 2016 from http://www.nhs.uk/chq/Pages/1019.aspx?CategoryID=69&SubCategoryID=692

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