PATIENT INFORMATION
Why do I have to fast before anaesthesia?
Anaesthesia and deep sedation can reduce the reflexes that normally protect your airway, such as coughing and swallowing. If food or liquid comes back up from the stomach while those reflexes are reduced, it can enter the lungs. This is called pulmonary aspiration and it can be serious, causing pneumonia or breathing problems.
Why the rules are not simply “the longer, the better”
Fasting instructions are designed to reduce aspiration risk without making you go without food or drink for longer than necessary. Going without fluids for many hours can cause thirst, headache, dizziness, low blood sugar and dehydration, and can make recovery less comfortable. This is why many hospitals have moved away from routine “nothing after midnight” instructions.
Why your plan may differ from someone else’s
The correct fasting time depends on what you consumed, your age, your health and the procedure. People with conditions that slow stomach emptying may need a different plan, for example people with:
- Diabetes affecting the stomach (gastroparesis)
- Significant reflux or swallowing problems
- Pregnancy
- Recent use of some medicines, including GLP-1 medicines or strong painkillers
Does fasting apply to local anaesthesia or sedation?
Sometimes. Even if you are not planned for a general anaesthetic, sedation or a change in plan may be needed. Follow the fasting instructions given for your procedure, even if you expect to be awake.