Before a gastroscopy: what you can and cannot do

Preparation for gastroscopy determines the safety, quality of the examination, and accuracy of biopsies. The primary goal is an empty stomach and predictable conditions for anesthesia or sedation. International recommendations are consistent: a minimum of 6 hours of fasting is required for solid foods and 2 hours for clear liquids. These intervals reduce the risk of aspiration and improve mucosal visibility without compromising the tolerability of the procedure. [1]

Some clinics allow small sips of water two hours before the procedure, and studies show that this can even reduce discomfort without compromising quality. However, any deviations from standards are agreed upon with the clinic conducting the study: the invitation letter usually specifies local regulations. Failure to adhere to the fasting regimen is a common reason for postponement. [2]

The fasting rules also imply restrictions on beverages. Only clear liquids are permitted: water, weak tea or coffee without milk, and clear juices without pulp. Milk and any dairy drinks are considered food, while soda and liquids with dyes impair visibility. Therefore, the "safe window" for water is shorter than for food. [3]

The details of preparation depend on the chosen method: orally with a throat spray or transnasally with a thin endoscope. With the transnasal technique, fasting requirements are the same, but the procedure is often easier to tolerate, and sedation is less frequently required. This affects the list of post-examination restrictions and whether a companion is needed. [4]

Table 1. Basic fasting intervals for adults

What	Minimum interval	Note
Solid foods, including milk	6 hours	Most often, 6-8 hours are recommended, depending on the clinic. [5]
Clear liquids	2 hours	Small sips of water are allowed for up to 2 hours. [6]
Medicines, wash down with water	Up to 2 hours	Take vital medications according to an individual plan. [7]

For children and adolescents: safe intervals

Children have separate, more fluid-friendly guidelines. Current pediatric recommendations allow for even shorter intervals for clear liquids to avoid dehydration and stress. While intervals for breast milk and formula differ, solid foods are still maintained at 6-8 hours. Individual adjustments depend on age and underlying conditions. [8]

The key principle is to avoid excessive fasting. Long breaks worsen well-being and do not improve safety. The endoscopy team should provide written instructions to parents in advance, including specific examples of permitted drinks. This reduces the risk of procedure disruption and repeat visits. [9]

Chronic medical conditions and medications are important to consider. For children with gastroesophageal reflux disease, neurological disorders, or those at risk of delayed gastric emptying, the doctor may adjust the intervals. Decisions are made on an individual basis after assessing the patient's medical history. [10]

If sedation is planned, the department will inform the patient in advance about the required breaks for fluids and whether a companion is needed after discharge. Children typically remain under observation until they have recovered satisfactorily, after which the team will allow fluids and food. [11]

Table 2. Children's fasting intervals

Age and nutrition	Clear liquids	Breast milk	Adapted mixture	Solid food
Newborns and infants	1-2 hours	3-4 hours	6 hours	6-8 hours
Children over 1 year old	1-2 hours	-	6 hours	6-8 hours
Teenagers	2 hours	-	-	6-8 hours
*Intervals are determined by the clinic; priority is given to the written instructions of the department. [12]

Drinks, smoking, chewing gum, and alcohol: what's allowed and what's definitely not

Only clear liquids are permitted 2 hours before the examination: water, weak tea or coffee without milk, and clear beverages without pulp. These liquids quickly clear the stomach and do not obscure the view. Opaque beverages, fermented dairy products, and juices with pulp are considered food and require 6 hours. It is best to follow the department's instructions. [13]

Smoking and chewing gum immediately before the examination are not recommended. Nicotine increases acid secretion and increases the risk of nausea, while gum and hard candies stimulate salivation and may disrupt fasting rules. Many clinics specifically state: no food, drink, gum, or hard candies for 6 hours before the gastroscopy; water should only be consumed up to 2 hours before. [14]

Alcohol is strictly contraindicated the day before and the day of the procedure. It increases the risk of vomiting, blood pressure instability, and unpredictable reactions to sedatives. Sedation restrictions remain in place after discharge: driving, operating machinery, and drinking alcohol are prohibited for 24 hours. [15]

With transnasal gastroscopy without sedation, post-procedure restrictions are minimal, but fasting preparation remains the same. If you're unsure whether a companion is needed, refer to your invitation letter: with a local spray without sedation, you can go home on your own; with sedation, a companion is required. [16]

Table 3. Clear liquids: what is allowed

Allowed up to 2 hours	Prohibited until 6 o'clock	Why
Still water	Any drinks with milk	Milk is considered food and is retained in the stomach. [17]
Weak tea without milk	Juices with pulp	Slows down emptying and impairs visibility. [18]
Weak black coffee without milk	Carbonated drinks and beverages with colorings	Risk of foaming and coloration of contents. [19]

Medications: How to handle antithrombotics and other medications

For diagnostic gastroscopy with possible targeted biopsy, the risk of bleeding is low. European guidelines indicate: acetylsalicylic acid is continued; P2Y12 receptor inhibitors are continued even with dual therapy; warfarin is usually continued, with monitoring to ensure the international normalized ratio remains within the therapeutic range; for direct oral anticoagulants, skipping the morning dose on the day of the procedure is often sufficient. The final decision is made by the attending physician. [20]

If high-risk interventions are planned, such as stricture dilation or extensive mucosal resection, the strategy changes: P2Y12 inhibitors are temporarily discontinued in advance, warfarin is discontinued and replaced with low-molecular-weight heparin depending on the thrombotic risk, and direct anticoagulants are withheld for several days, taking into account renal function. For purely diagnostic gastroscopy, these measures are usually not required. [21]

For patients receiving diabetes medications, a separate plan is essential. Insulin and metformin are adjusted individually to avoid hypoglycemia during fasting. Regarding sodium-glucose cotransporter 2 inhibitors, there are consistent recommendations: to avoid euglycemic ketoacidosis, they are discontinued 3 days before a planned procedure involving anesthesia or sedation, and 4 days before when using ertugliflozin. This rule is widely used in hospitals. [22]

For glucagon-like peptide-1 receptor agonists, the approach is being refined. Accumulated data show a risk of delayed gastric emptying and the detection of residual contents during upper endoscopy. The position of gastroenterological societies for 2024-2025: in most cases, continuation of therapy is permitted provided a 24-hour clear diet is maintained before endoscopy and the team is informed; the decision is made in consultation with the physician. [23]

Table 4. Antithrombotic drugs before diagnostic gastroscopy

Group	Basic approach	Comment
Acetylsalicylic acid	Continue	For diagnostic procedure with biopsy. [24]
P2Y12 inhibitors	Continue	Even with dual therapy; check with your cardiologist if in doubt. [25]
Warfarin	Continue	Monitor the international normalized ratio within the therapeutic range. [26]
Direct oral anticoagulants	Skip the morning dose	For purely diagnostic gastroscopy; individualize in case of high bleeding. [27]

Table 5. Medicines for diabetes and weight loss drugs

Preparation	What to do	Justification
Insulin, metformin	Individual plan	Avoid hypoglycemia during fasting. [28]
Sodium-glucose cotransporter 2 inhibitors	Stop 3 days in advance, ertugliflozin - 4 days in advance	Prevention of euglycemic ketoacidosis during anesthesia or sedation. [29]
Glucagon-like peptide 1 receptor agonists	24-hour clear diet; decide with your doctor	Reducing the risk of gastric residual, taking into account new consent documents. [30]

If a Helicobacter pylori test is planned

If a physician plans a rapid urease test or histological testing to detect Helicobacter pylori, therapy is adjusted in advance to avoid false-negative results. International consensus guidelines recommend discontinuing proton pump inhibitors at least 14 days before the follow-up test, and bismuth preparations and antibiotics at least 4 weeks before the follow-up test. These timings are also important for the post-therapy "test of cure." [31]

If discontinuing proton pump inhibitors is undesirable due to severe symptoms, the decision is made on an individual basis. Sometimes, the doctor postpones invasive bacterial testing and performs a purely diagnostic gastroscopy, postponing infection confirmation until a more convenient time. This approach prevents erroneous treatment. [32]

In gastric ulcers, monitoring healing and biopsy to rule out neoplasia are often more important than immediate testing for Helicobacter pylori. In this case, the doctor schedules a follow-up examination and provides precise instructions on when to return for laboratory or breath tests. [33]

Always check with your referral to determine whether bacterial testing is planned—this detail can influence the need to discontinue acid-reducing medications. In the absence of such plans, routine discontinuation is often unnecessary. [34]

Table 6. Dos and Don'ts the Day Before a Gastroscopy: A Brief Checklist

Action	Allowed	It is forbidden	Explanation
Drink clear liquids	Up to 2 hours	Milk drinks	Milk is considered a food. [35]
Take vital medications	According to plan	Without arbitrary cancellation	Wash down with a small amount of water. [36]
Smoking, chewing gum, lollipops	-	Avoid	May violate fasting rules. [37]
Alcohol	-	Prohibited	Increases the risk of sedation. [38]
Glucagon-like peptide 1 receptor agonists	24-hour transparent diet	-	Joint decision with the doctor. [39]

On the day of the procedure: documents, safety and equipment

On the day of your examination, please bring your referral, medication and allergy list, recent test results, and information about previous cardiac and vascular procedures. This saves time and helps the team quickly adjust the plan if a biopsy or diathermy is needed. Wear comfortable clothing and remove jewelry; if using a transnasal technique, you may be asked to clear your nasal passages. [40]

If local anesthesia is administered to the pharynx, eating and drinking are prohibited until the swallowing reflex returns, which usually takes about 30 minutes. If sedation is chosen, the department will request the presence of an accompanying person in advance, and after discharge, driving, operating machinery, and making important decisions are prohibited for 24 hours. This is a safety standard. [41]

Before the procedure, the doctor will reconfirm fasting and medication adherence as planned. During sedation, respiration and circulation are monitored, and if risk factors are present, the team will select a gentle regimen or transnasal technique. Detailed national guidelines for sedation are published and updated regularly. [42]

If you experience signs of a cold, acute vomiting, fever, recently changed anticoagulants, or hypoglycemia, please notify us in advance. Some situations require rescheduling to avoid compromising safety or the quality of the results. The department will assess the risks and schedule a new date. [43]

Table 7. When is it best to postpone gastroscopy?

Situation	Why is this important?	What do they usually do?
Fasting is broken	Risk of aspiration, poor visibility	Postponement to another date. [44]
Acute respiratory tract infection	Risk of complications from sedation and cough	Get well and come back later. [45]
Recent changes in anticoagulants without approval	Risk of bleeding or thrombosis	Contact your healthcare provider and adjust your plan. [46]
Taking sodium-glucose cotransporter 2 inhibitors without discontinuation	Risk of euglycemic ketoacidosis	Postponement and safe cancellation by deadline. [47]
Recent use of glucagon-like peptide 1 receptor agonists without 24-hour fluid preparation	Risk of residual contents in the stomach	Do the 24-hour clear diet or postpone it. [48]

Short answers to frequently asked questions

Is it okay to drink water in the morning? Small sips of clear water are acceptable up to 2 hours before the procedure. Always follow the department's instructions. [49]

What about my heart medications and anticoagulants? For diagnostic gastroscopy, aspirin and P2Y12 receptor inhibitors are usually continued, warfarin is also continued at the therapeutic international normalized ratio, and direct anticoagulants are often skipped only for the morning dose. The final decision rests with the attending physician. [50]

If I'm taking medications for weight loss or diabetes, sodium-glucose cotransporter 2 inhibitors should be discontinued 3 days before anesthesia or sedation. For glucagon-like peptide 1 receptor agonists, 24 hours of clear diet and team approval are usually sufficient. [51]

Can I chew gum? No. Chewing gum and hard candies are prohibited before a gastroscopy to avoid violating fasting rules and increasing the risk of nausea. [52]

Is a companion necessary? For topical throat sprays, a companion is generally not needed. For sedation, a companion is required, and restrictions apply for 24 hours. [53]