Epitope Health
Menu
Not medical advice. Possible anaphylaxis: use epinephrine and call 911.Read the full note

Epitope Health teaches what published research and FDA labels say, and how strong that evidence is. It cannot know your situation, and nothing here is a diagnosis, a dose for one person, or a decision about whether a food, medicine or procedure suits one person. Those decisions belong with a licensed clinician who can examine you.

If a reaction is happening now, use epinephrine if it has been prescribed and call 911. After surgery, trouble breathing or chest pain needs 911. If you are thinking about harming yourself, call or text 988, any time.

Home / Surgery Ready / Before surgery
For clinicians

Fasting before surgery: the rules and the reasons

Why the team asks for an empty stomach, what the guidelines say about clear fluids and solid food, and what trials found about shorter fasts and carbohydrate drinks.

6 minute read, written for clinicians7 sources, each checked word for wordLibrary checked October 18, 2026

A glass pitcher of water and a drinking glass on a sunlit table

This is the clinician view. It keeps every sentence of the plain guide and adds, for each section, the study design and citations of its sources, exact figures, and label wording quoted whole, marked For clinicians. Every added sentence is cited and checked like the rest. Back to plain language.

In short

  • Fasting before anesthesia aims to reduce the amount and acidity of stomach contents, lowering the risk of regurgitation and aspiration.E1Strong1
  • European guidelines encourage clear fluids up to 2 hours before elective surgery and stop solid food 6 hours before.E2Good2
  • A Cochrane review found no evidence that a shorter fluid fast raises aspiration risk compared with nothing by mouth from midnight.E1Strong1
  • The surgical team sets each person's fasting times. The times on this page are what guidelines say in general.

How sure each claim is:E1StrongE2GoodOfficial textReviewWhat the grades meanUnderlined words open a definition

Why fast at all?

Fasting before general anesthesia aims to reduce the volume and acidity of what is in the stomach during surgery. This reduces the risk of regurgitation and aspiration (stomach contents getting into the lungs).E1Strong1

The evidence in this section (1 source)
SourceDesignGradeCitations (NIH iCite)
1 Brady M, Cochrane Database Syst Rev, 2003Systematic reviewE1Strong396 (RCR 13.06)

What do the guidelines say?

The European Society of Anaesthesiology encourages adults and children to drink clear fluids up to 2 hours before elective surgery, including cesarean section. All but one member of the group considered tea or coffee with a little milk to still be a clear fluid. A little milk meant up to about one fifth of the volume.E2Good2

It says solid food should stop 6 hours before elective surgery. But it says an operation should not be cancelled or delayed just because someone is chewing gum, sucking a hard candy or smoking right before anesthesia.E2Good2

It applies the same advice to people with obesity, reflux and diabetes, and to pregnant women not in labor.E2Good2

The American Society of Anesthesiologists updated its fasting guidelines in 2023. The update addresses carbohydrate-containing clear drinks (with or without protein), chewing gum, and how long children fast.E2Good3

For clinicians

The ESA guideline's key recommendations, quoted as written:

The key recommendations are that adults and children should be encouraged to drink clear fluids up to 2 h before elective surgery (including caesarean section) and all but one member of the guidelines group consider that tea or coffee with milk added (up to about one fifth of the total volume) are still clear fluids.

Solid food should be prohibited for 6 h before elective surgery in adults and children, although patients should not have their operation cancelled or delayed just because they are chewing gum, sucking a boiled sweet or smoking immediately prior to induction of anaesthesia.

These recommendations also apply to patients with obesity, gastro-oesophageal reflux and diabetes and pregnant women not in labour.

Quoted word for word from Perioperative fasting in adults and children: guidelines from the European Society of Anaesthesiology E2Good2

The scope of the 2023 ASA update, quoted as written:

These practice guidelines are a modular update of the "Practice guidelines for preoperative fasting and the use of pharmacologic agents to reduce the risk of pulmonary aspiration: Application to healthy patients undergoing elective procedures." The guidance focuses on topics not addressed in the previous guideline: ingestion of carbohydrate-containing clear liquids with or without protein, chewing gum, and pediatric fasting duration.

Quoted word for word from 2023 American Society of Anesthesiologists Practice Guidelines for Preoperative Fasting: Carbohydrate-containing Clear Liquids with or without Protein, Chewing Gum, and Pediatric Fasting Duration-A Modular Update of the 2017 American Society of Anesthesiologists Practice Guidelines for Preoperative Fasting E2Good3
The evidence in this section (2 sources)
SourceDesignGradeCitations (NIH iCite)
2 Smith I, Eur J Anaesthesiol, 2011GuidelineE2Good584 (RCR 25.03)
3 Joshi GP, Anesthesiology, 2023GuidelineE2Good252 (RCR 46.44)

Is fasting from midnight necessary?

A Cochrane review found no evidence that a shortened fluid fast increases the risk of aspiration, regurgitation or related harm compared with the standard nothing-by-mouth-from-midnight policy.E1Strong1

Letting patients drink water before surgery resulted in significantly lower stomach volumes.E1Strong1

For clinicians

The Cochrane review's finding, quoted as written:

There was no evidence to suggest a shortened fluid fast results in an increased risk of aspiration, regurgitation or related morbidity compared with the standard 'nil by mouth from midnight' fasting policy. Permitting patients to drink water preoperatively resulted in significantly lower gastric volumes.

Quoted word for word from Preoperative fasting for adults to prevent perioperative complications E1Strong1
The evidence in this section (1 source)
SourceDesignGradeCitations (NIH iCite)
1 Brady M, Cochrane Database Syst Rev, 2003Systematic reviewE1Strong396 (RCR 13.06)

What about carbohydrate drinks?

Enhanced recovery (ERAS) guidelines replaced overnight fasting with carbohydrate drinks 2 hours before surgery.Review4

A Cochrane review found carbohydrate drinks before surgery linked with a small reduction in hospital stay in adults, with no change in complication rates. Aspiration pneumonitis was not reported in any patient.E1Strong5

For clinicians

The Cochrane review of preoperative carbohydrate, quoted as written:

Preoperative carbohydrate treatment was associated with a small reduction in length of hospital stay when compared with placebo or fasting in adult patients undergoing elective surgery. It was found that preoperative carbohydrate treatment did not increase or decrease postoperative complication rates when compared with placebo or fasting.

Aspiration pneumonitis was not reported in any patients, regardless of treatment group allocation.

Quoted word for word from Preoperative carbohydrate treatment for enhancing recovery after elective surgery E1Strong5

Ljungqvist's review reports that ERAS protocols have shortened hospital stay by 30% to 50%, with similar reductions in complications, while readmissions and costs are reduced.Review4

The evidence in this section (2 sources)
SourceDesignGradeCitations (NIH iCite)
4 Ljungqvist O, JAMA Surg, 2017Expert reviewReview2,764 (RCR 162.2)
5 Smith MD, Cochrane Database Syst Rev, 2014Systematic reviewE1Strong293 (RCR 13.69)

Do weight-loss and diabetes injections change this?

GLP-1 medicines such as semaglutide can leave food in the stomach despite fasting. This has its own guide: Medicines to discuss before surgery.Official text6

For clinicians

The Ozempic label, quoted as written:

There have been rare postmarketing reports of pulmonary aspiration in patients receiving GLP-1 receptor agonists undergoing elective surgeries or procedures requiring general anesthesia or deep sedation who had residual gastric contents despite reported adherence to preoperative fasting recommendations.

Quoted word for word from OZEMPIC (semaglutide) injection, Prescribing Information Official text6

In Sen's study of 124 participants (median age 56 years; 60% female), increased residual gastric content on preprocedural gastric ultrasound was found in 56% (35 of 62) taking a GLP-1 receptor agonist and 19% (12 of 62) not taking one.E2Good7

GLP-1 receptor agonist use was independently associated with increased residual gastric content.E2Good7

The evidence in this section (2 sources)
SourceDesignGradeCitations (NIH iCite)
6 Novo Nordisk, 2026FDA labelOfficial textNot tracked
7 Sen S, JAMA Surg, 2024Observational studyE2Good163 (RCR 33.17)

Questions you might bring to your anesthesia team

  1. Exactly when should eating and drinking stop before my procedure?
  2. Which drinks count as clear fluids, and is a carbohydrate drink part of the plan?
  3. Do any of my medicines change the fasting plan?
  4. What should happen with my morning medicines on the day of surgery?

Every claim in this guide was written from its sources and checked against them word for word. Its clinical review by Dr. Recio, a practicing nurse anesthesiologist (CRNA), is pending. This line changes when the review is done.

Sources

Each source opens on PubMed, DailyMed or the publisher's page. Under each one are the exact words from it that this page relies on, copied word for word and checked against the original.

  1. Preoperative fasting for adults to prevent perioperative complications. Brady M, Cochrane Database Syst Rev, 2003. E1Strong Systematic reviewPMID 14584013; DOI 10.1002/14651858.CD004423; cited 396 times, relative citation ratio 13.06 (NIH iCite, 2026-10-18)
    The words this page rests on
    Fasting before general anaesthesia aims to reduce the volume and acidity of stomach contents during surgery, thus reducing the risk of regurgitation/aspiration.
    There was no evidence to suggest a shortened fluid fast results in an increased risk of aspiration, regurgitation or related morbidity compared with the standard 'nil by mouth from midnight' fasting policy. Permitting patients to drink water preoperatively resulted in significantly lower gastric volumes.
  2. Perioperative fasting in adults and children: guidelines from the European Society of Anaesthesiology. Smith I, Eur J Anaesthesiol, 2011. E2Good GuidelinePMID 21712716; DOI 10.1097/EJA.0b013e3283495ba1; cited 584 times, relative citation ratio 25.03 (NIH iCite, 2026-10-18)
    The words this page rests on
    The key recommendations are that adults and children should be encouraged to drink clear fluids up to 2 h before elective surgery (including caesarean section) and all but one member of the guidelines group consider that tea or coffee with milk added (up to about one fifth of the total volume) are still clear fluids.
    Solid food should be prohibited for 6 h before elective surgery in adults and children, although patients should not have their operation cancelled or delayed just because they are chewing gum, sucking a boiled sweet or smoking immediately prior to induction of anaesthesia.
    These recommendations also apply to patients with obesity, gastro-oesophageal reflux and diabetes and pregnant women not in labour.
  3. 2023 American Society of Anesthesiologists Practice Guidelines for Preoperative Fasting: Carbohydrate-containing Clear Liquids with or without Protein, Chewing Gum, and Pediatric Fasting Duration-A Modular Update of the 2017 American Society of Anesthesiologists Practice Guidelines for Preoperative Fasting. Joshi GP, Anesthesiology, 2023. E2Good GuidelinePMID 36629465; DOI 10.1097/ALN.0000000000004381; cited 252 times, relative citation ratio 46.44 (NIH iCite, 2026-10-18)
    The words this page rests on
    These practice guidelines are a modular update of the "Practice guidelines for preoperative fasting and the use of pharmacologic agents to reduce the risk of pulmonary aspiration: Application to healthy patients undergoing elective procedures." The guidance focuses on topics not addressed in the previous guideline: ingestion of carbohydrate-containing clear liquids with or without protein, chewing gum, and pediatric fasting duration.
  4. Enhanced Recovery After Surgery: A Review. Ljungqvist O, JAMA Surg, 2017. Review Expert reviewPMID 28097305; DOI 10.1001/jamasurg.2016.4952; cited 2,764 times, relative citation ratio 162.2 (NIH iCite, 2026-10-18)
    The words this page rests on
    The ERAS Society, an international nonprofit professional society that promotes, develops, and implements ERAS programs, publishes updated guidelines for many operations, such as evidence-based modern care changes from overnight fasting to carbohydrate drinks 2 hours before surgery, minimally invasive approaches instead of large incisions, management of fluids to seek balance rather than large volumes of intravenous fluids, avoidance of or early removal of drains and tubes, early mobilization, and serving of drinks and food the day of the operation.
    Enhanced Recovery After Surgery protocols have resulted in shorter length of hospital stay by 30% to 50% and similar reductions in complications, while readmissions and costs are reduced.
  5. Preoperative carbohydrate treatment for enhancing recovery after elective surgery. Smith MD, Cochrane Database Syst Rev, 2014. E1Strong Systematic reviewPMID 25121931; DOI 10.1002/14651858.CD009161.pub2; cited 293 times, relative citation ratio 13.69 (NIH iCite, 2026-10-18)
    The words this page rests on
    Preoperative carbohydrate treatment was associated with a small reduction in length of hospital stay when compared with placebo or fasting in adult patients undergoing elective surgery. It was found that preoperative carbohydrate treatment did not increase or decrease postoperative complication rates when compared with placebo or fasting.
    Aspiration pneumonitis was not reported in any patients, regardless of treatment group allocation.
  6. OZEMPIC (semaglutide) injection, Prescribing Information. Novo Nordisk, 2026. Official text FDA label
    The words this page rests on
    There have been rare postmarketing reports of pulmonary aspiration in patients receiving GLP-1 receptor agonists undergoing elective surgeries or procedures requiring general anesthesia or deep sedation who had residual gastric contents despite reported adherence to preoperative fasting recommendations.
  7. Glucagon-Like Peptide-1 Receptor Agonist Use and Residual Gastric Content Before Anesthesia. Sen S, JAMA Surg, 2024. E2Good Observational studyPMID 38446466; DOI 10.1001/jamasurg.2024.0111; cited 163 times, relative citation ratio 33.17 (NIH iCite, 2026-10-18)
    The words this page rests on
    Among the 124 participants (median age, 56 years [IQR, 46-65 years]; 75 [60%] female), the prevalence of increased RGC was 56% (35 of 62) in patients with GLP-1 RA use (exposure group) compared with 19% (12 of 62) in patients who were not taking a GLP-1 RA drug (control group).
    Use of a GLP-1 RA was independently associated with increased RGC on preprocedural gastric ultrasonography. The findings suggest that the preprocedural fasting duration suggested by current guidelines may be inadequate in this group of patients at increased risk of aspiration under anesthesia.