Why Can't You Drink Water Before Surgery?

Many doctors and hospitals require patients to abstain from food and drink for a certain amount of time before surgery. The reasons for not being allowed to drink water prior to being operated on are in the patient's best interest.


The purpose of fasting before an operation is to reduce the chances of aspiration. Aspiration can damage the patient's lungs and can cause fatal consequences.


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Aspiration occurs when fluid from the stomach—from water, food or anything else—enters the lungs. It can happen when patients are under anesthesia, and is very dangerous.

Solid Food

The American Society of Anesthesiologists (ASA) recommends that you should take light meals (for example, dry toast) no later than six hours before an operation.


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The ASA also recommends that you not drink milk or other unclear liquids (such as pulpy juice) six hours or less before an operation, and that you should not drink water or other clear liquids two hours or less before an operation.


Different hospitals and doctors have different rules for fasting before surgery, but you should always follow your doctor's recommendations. Some doctors may require that you ingest solid food no later than the midnight before the surgery.