Patient education: Fasting before surgery (The Basics)

What does "fasting" mean? — "Fasting" means not eating or drinking anything for a period of time. People sometimes need to fast before getting a medical test or surgery.

Will I need to fast before my surgery? — You might. It depends on what kind of surgery you are having, and what kind of anesthesia you need. "Anesthesia" is a medical term for different types of medicine given during surgery or another procedure. These medicines make sure that you do not feel pain during your surgery.

If you have a scheduled surgery or procedure, your doctor or nurse will tell you if you need to fast before it. If you are only getting "local anesthesia," you probably won't need to fast. Local anesthesia is medicine to numb a small part of your body. It can be given as a shot, or as a cream, gel, or spray that goes on the skin.

You will need to fast if you are getting any of the following:

●General anesthesia – This type of anesthesia makes you unconscious so you can't feel, see, or hear anything during surgery. Some of the medicines are given through a thin tube that goes into a vein, called an "IV." Others are gases that you breathe in.

●Regional anesthesia – This type of anesthesia blocks pain in 1 area of your body, such as an arm, leg, or the lower half of your body. The doctor will inject medicine around the nerves that go to the area where you are getting surgery.

●Sedation – This is the term for getting medicines to make you relax and feel sleepy.

Why do I need to fast? — You need to fast to make sure that your stomach is as empty as possible when you get anesthesia. If you have food or liquid in your stomach, some of it could get into your lungs while you are under anesthesia. This is called "aspiration." Normally, your body is able to prevent this from happening. But anesthesia medicines make it harder for your body to prevent this.

Aspiration is rare, but can be dangerous if it does happen. That's because it can lead to infection, lung damage, or breathing problems.

How long before my surgery do I have to stop eating and drinking? — It depends. Your doctor or nurse will give you instructions for your situation. An example of these instructions might be:

●Do not eat any solid foods for 6 to 8 hours before your surgery. You should also avoid milk and cream after this time, even small amounts like in coffee or tea. That's because milk "curdles" into small solid bits in the stomach.

●You can drink clear liquids up to 2 hours before your surgery. Clear liquids include water, juice with no pulp, and coffee or tea without milk or cream.

●Do not eat or drink anything, even clear liquids, during the 2 hours before your surgery. However, if you are told to take a medicine during this time, you can take it with a sip of water.

Your hospital or clinic might have slightly different rules. For example, you might need to:

●Fast for longer after a meal that has a lot of meat or fat

●Avoid chewing gum or sucking on candy after a certain time

There are also special rules for babies and young children who need surgery. For example:

●Most hospitals say that you can give breast milk up to 4 hours before surgery. If your baby drinks formula, you might have to stop giving it sooner.

●Many hospitals allow children to have clear liquids up to 1 hour before surgery. Your child's doctor or nurse can tell you exactly what to do.

The most important thing is to follow the instructions given to you by the doctor or nurse.

Should I keep taking my medicines before surgery? — It depends. Your doctor or nurse will tell you which medicines you should take and when. Some medicines need to be stopped before surgery. But for others, it's important that you keep taking them as usual. You might also get new medicines to take before surgery.

Take the medicines your doctor or nurse tells you to. If you need to take medicine before your surgery, you can take it with a sip of water. If you normally take your medicine with something else, like applesauce, talk to your doctor or nurse about what to do.

What will happen if I don't fast? — If you don't follow instructions about when to stop eating and drinking, you could be putting your health at risk. Be honest with your doctor or nurse if you did not follow the rules, even if it was an accident. If this happens, your surgery might need to be delayed until a later time.

More on this topic

Patient education: Anesthesia (The Basics)
Patient education: Aspiration pneumonia (The Basics)
Patient education: Questions to ask if you are having surgery or a procedure (The Basics)
Patient education: Moderate or deep sedation for procedures in children (The Basics)
Patient education: Sedation for procedures in adults (The Basics)
Patient education: Clear liquid diet (The Basics)
Patient education: Full liquid diet (The Basics)