{"id":3016,"date":"2026-10-20T11:39:12","date_gmt":"2026-10-20T02:39:12","guid":{"rendered":"https:\/\/iwaw.kr\/en\/2026\/10\/20\/health-screening-fasting-time-7bfc94ca09\/"},"modified":"2026-10-20T11:39:28","modified_gmt":"2026-10-20T02:39:28","slug":"health-screening-fasting-time-7bfc94ca09","status":"publish","type":"post","link":"https:\/\/iwaw.kr\/en\/2026\/10\/20\/health-screening-fasting-time-7bfc94ca09\/","title":{"rendered":"Health Screening Fasting Time: Check Precautions on Whether to Drink Water and Coffee"},"content":{"rendered":"


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Ahead of a national health screening, the most common precaution guided first and the rule that must be followed most thoroughly is ‘fasting before the screening.’ The reason fasting is essential in a health screening is to measure the physiological state of the human body with the most accurate and error-free figures to diagnose diseases early. Because the food and moisture we consume cause direct changes in various biometric indicators such as blood components, blood sugar, liver function figures, and cholesterol, maintaining a fasting state with the stomach and intestines completely emptied is scientifically essential to obtain accurate test results.<\/p>\n

The basic rule of fasting is to finish dinner with light and easily digestible food before 9 PM on the day before the screening, and not consume any food or drink at all, including water, from then until the screening is completed. Generally, maintaining a fasting state of at least 8 hours or more, and ideally 10 to 12 hours or more, can completely block nutrients or digestive juices in the blood from affecting the test results. In particular, if blood tests and upper gastrointestinal endoscopies are scheduled, this fasting rule becomes a decisive factor determining the reliability of the tests.<\/p>\n

If you fail to properly follow the fasting rules, consume food or water, and undergo the screening, your blood sugar level may be measured higher than actual, leading to a misdiagnosis even if you do not have diabetes, or your triglyceride and liver function figures may be distorted, causing the hassle of having to undergo unnecessary re-examinations. Therefore, for a successful and accurate health screening, thoroughly understanding and complying with the fasting times and basic rules guided by the Corporation and the hospital is the wisest first step to protecting your own health.<\/p>\n

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Permitted Criteria for Water Intake During Fasting and Timing When Drinking Is Allowed<\/h2>\n

One of the most frequently asked and curious questions during the fasting time starting from the night before the health screening is, “Can I really not even drink a sip of water?” Starting with the conclusion, although there may be differences depending on the type of screening, generally, water intake is also strictly restricted as a rule for accurate testing. However, knowing the specific permitted criteria and the timing when drinking is allowed accurately can relieve unnecessary thirst and anxiety.<\/p>\n

In cases where only general blood tests or urine tests are conducted, some hospitals permit a small amount of plain water a few hours before the screening. However, if precise examinations of the digestive system such as an upper gastrointestinal endoscopy, colonoscopy, or abdominal ultrasound are scheduled together, drinking water is strictly prohibited. Moisture remaining inside the stomach or intestines not only obstructs the endoscopic field of view and makes accurate mucosal observation impossible, but can also cause safety accidents such as vomiting or aspiration pneumonia during sedation endoscopy. Therefore, the intake of all liquids, including water, must be completely stopped for at least 4 to 8 hours or more before the screening.<\/p>\n

If you are in an unavoidable situation where you must drink water due to extreme thirst or regular medications you are taking (e.g., blood pressure medication, etc.), you should consume only a very small amount (less than half a paper cup) of plain water in a limited manner, just enough to wet your mouth, in accordance with the prior guidance of the screening institution or attending physician. At this time, sugar, syrup, milk, flavored beverages, or ice are strictly not permitted, and only pure water can be exceptionally recognized. Therefore, for a safe and prompt screening, it is wisest to prioritize the guidance instructions of the screening center where you made your reservation.<\/p>\n

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Effects of Beverage Intake Such as Coffee, Tea, and Milk on Screening Results<\/h2>\n

During the fasting time continuing from the night before the national health screening, the part that many people are most curious about and easily feel tempted by is whether to consume beverages other than water, especially coffee, tea, and milk. Starting with the conclusion, all beverages except pure water, such as coffee, tea, milk, juice, and carbonated drinks, can distort screening results and therefore must never be consumed during the fasting time.<\/p>\n

First, beverages containing caffeine, such as morning coffee or green tea drunk in the morning, can stimulate gastric acid secretion and cause temporary changes in heartbeat or blood pressure. In particular, if you drink coffee or tea ahead of an upper gastrointestinal endoscopy or gastrointestinal fluoroscopy, pigments may deposit on the gastric mucosa or affect gastrointestinal motility, hindering accurate lesion observation, and can also induce errors in blood sugar and hormone figures during blood tests. Even if it is black coffee, caffeine and additive components affect biological responses, so it is prohibited without exception.<\/p>\n

Second, dairy products or nutritional drinks containing protein, fat, and carbohydrates, such as milk, soy milk, and caffe latte, constitute food items in themselves. Consuming them immediately raises blood sugar, causes triglyceride levels to spike sharply, and breaks the fasting state of the digestive system. Therefore, not only does it lower the accuracy of blood tests, but it also induces intestinal gas during abdominal ultrasounds, making observation of major organs such as the liver, gallbladder, and pancreas difficult.<\/p>\n

As such, even seemingly minor things like a cup of coffee or tea, or a sip of milk, can significantly drop the reliability of the screening and become a cause for re-examination. Therefore, for a successful health check-up and accurate results, the wisdom of thoroughly refraining from consuming all beverages except for the minimum permitted plain water from the evening before the check-up until the check-up is finished is necessary.<\/p>\n

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Dietary Control on the Evening Before the Screening and Types of Foods to Watch Out For<\/h2>\n

Dinner on the evening before the national health screening is a very important process that has a decisive influence on maintaining a fasting state the next morning and obtaining accurate screening results. It is easy to think that you only need to endure breakfast or lunch on the day before the screening, but depending on what food you eat and how you eat it on the evening before, your blood sugar, triglycerides, and the state of residues in your stomach and intestines can completely change.<\/p>\n

It is recommended to finish dinner on the evening before the health check-up with light and easily digestible food between 7 PM and 9 PM, which is at least 8 to 12 hours before the screening time. You should consume light food mainly consisting of soft carbohydrates such as rice or porridge, around 50 to 70 of your usual meal amount, and avoid stimulating or greasy foods so as not to put a burden on your stomach and intestines.<\/p>\n

In particular, the types of food to avoid in the evening meal on the day before are as follows.<\/p>\n