Why does drinking too much water cause discomfort?

Under normal circumstances, excessive water intake can cause discomfort, primarily because the body cannot promptly eliminate the surplus water, leading to an imbalance in water metabolism and subsequently increasing the burden on organs and causing electrolyte disturbances. The detailed explanation is as follows:

The human body has a fixed regulatory mechanism for water metabolism, with the kidneys being the primary excretory organs. Under normal conditions, they can convert excess water into urine and expel it from the body. However, when water is consumed too quickly or in quantities far exceeding the kidneys' excretory capacity, the surplus water accumulates in the body, causing a sharp increase in blood volume. This forces the heart to work harder to maintain circulation, potentially resulting in discomfort such as chest tightness and shortness of breath. At the same time, the large influx of water dilutes electrolytes in the bloodstream, particularly reducing sodium ion concentration, which leads to hyponatremia. Hyponatremia disrupts the osmotic pressure balance between cells and their surrounding environment, causing water to enter cells and induce cellular swelling. If brain cells swell, symptoms such as headache, dizziness, nausea, and vomiting may occur, and in severe cases, confusion or altered consciousness may develop.

In addition, excessive water intake can rapidly overfill the gastrointestinal tract, irritating the mucous membranes and causing bloating, abdominal pain, and frequent urination, further exacerbating physical discomfort.

Therefore, daily water consumption should follow the principle of "small amounts frequently," with intake adjusted according to factors such as temperature and physical activity, avoiding large volumes of water in a single session. If significant discomfort occurs due to excessive water intake, drinking should be stopped immediately. In cases of severe symptoms, medical attention is necessary to restore the body's water and electrolyte balance through professional intervention.