What happens when you drink coffee on an empty stomach in the morning?
Nov 07, 2025
Source: Cainiu Health
Dr. Yu Yongchao
Introduction
Drinking coffee on an empty stomach in the morning may lead to gastrointestinal discomfort, blood sugar fluctuations, nervous system stimulation, worsened dehydration, and excessive gastric acid secretion, with more noticeable health impacts on certain individuals. If persistent stomach pain, palpitations, or dizziness occur after drinking coffee on an empty stomach, medical attention is recommended. Caffeine in coffee can irritate the gastric mucosa, and without food in the stomach to act as a buffer when fasting, this effect is intensified.
Drinking coffee on an empty stomach in the morning may lead to gastrointestinal discomfort, blood sugar fluctuations, nervous system stimulation, worsened dehydration, and excessive gastric acid secretion, with relatively significant health impacts for certain individuals. If persistent stomach pain, palpitations, or dizziness occur after drinking coffee on an empty stomach, medical attention is recommended.
1. Gastrointestinal discomfort: Caffeine in coffee stimulates the gastric mucosa. When the stomach is empty, there is no food to buffer this effect, making it easier to trigger stomach spasms, bloating, pain, nausea, and acid reflux. This is especially pronounced in individuals with gastritis or gastric ulcers.
2. Blood sugar fluctuations: In a fasting state, blood glucose levels are naturally low. Caffeine may interfere with insulin secretion, causing a brief spike in blood sugar followed by a rapid drop, leading to symptoms similar to hypoglycemia such as dizziness, fatigue, and difficulty concentrating.
3. Nervous system stimulation: On an empty stomach, caffeine is absorbed more quickly and rapidly affects the nervous system, potentially causing increased heart rate, palpitations, anxiety, and heightened morning stress, which may negatively affect emotional stability throughout the day.
4. Worsened dehydration: Coffee has a diuretic effect. Since the body is already in a mildly dehydrated state after overnight metabolism, drinking coffee on an empty stomach accelerates fluid loss, possibly exacerbating symptoms like dry mouth and dry skin.
5. Excessive gastric acid secretion: Caffeine promotes the secretion of gastric acid. Without food in the stomach to neutralize it, excess acid may damage the protective mucosal barrier, increasing the long-term risk of developing gastric conditions.
Before drinking coffee in the morning, it's advisable to eat a piece of bread, drink a glass of milk, or have an egg to reduce caffeine's irritation on the digestive tract. Opt for lower-strength coffee and avoid excessive consumption. Individuals with sensitive stomachs should consider shifting their coffee intake to half an hour after a meal.
