Fasting before surgery: how many hours without eating or drinking?

Why fasting is required

Anesthesia relaxes the reflexes that normally protect your airway. If the stomach still contains food or liquid, its contents can flow back up and into the lungs (pulmonary aspiration), a rare but serious complication. Fasting empties the stomach so that anesthesia can be performed safely — which is why an operation is often postponed when fasting rules were not followed.

The usual fasting times for adults

• Solid food and a light meal: stop at least 6 hours before the scheduled time of anesthesia.
• Fatty or fried food, meat, a heavy meal: often at least 8 hours.
• Milk and drinks containing milk: treated like food, usually 6 hours.
• Clear liquids (water, clear apple juice without pulp, tea or black coffee without milk, clear sugary drinks): often allowed up to 2 hours before.
• No alcohol in the 24 hours before surgery.

For babies and children, the times are different (for example, breast milk is often allowed up to 4 hours before). The team will give parents specific instructions.

Don't fast longer than necessary

Fasting "from midnight" for a surgery scheduled in the afternoon used to be common, but going too long without drinking causes thirst, headaches, low blood pressure and discomfort, without any added safety. If your team allows clear liquids until 2 hours before, drinking water or a clear sugary drink in the morning is usually recommended.

Your medications on the day of surgery

• Take the medications your team told you to take, with a small sip of water, even while fasting.
• Some treatments must be stopped or adjusted beforehand: blood thinners, diabetes medications, and some anti-inflammatories.
• If you take a weekly injection for diabetes or weight loss (GLP-1 medications such as semaglutide or tirzepatide), tell your anesthesia team: these drugs slow stomach emptying and may require special instructions.
• Don't take a sedative or sleeping pill before surgery unless it was prescribed by your anesthesia team.

Common mistakes that can delay your operation

• Having coffee with milk or a "small" breakfast on the morning of surgery.
• Chewing gum, sucking candy or smoking on the morning of surgery: ask your team, most ask you to avoid them.
• Counting the hours from the time you leave home instead of the scheduled time of the procedure.
• Not mentioning that you ate or drank by mistake: always tell the team, they will decide what is safe.

Making the instructions impossible to miss

Fasting mistakes are one of the most frequent causes of last-minute cancellations, often because the instructions were given weeks earlier, on paper. With Melav, the clinic's practical information and the surgeon's fasting instructions are sent to each patient by SMS at J-15, J-3 and J-1, in their own language, and MelavIA can answer questions like "can I drink water tomorrow morning?" from the surgeon's own instructions — at any hour.