Water poisoning is caused by excessive consumption of water during a short period of time. This leads to a disruption in normal brain function due to the imbalance of electrolytes in the body’s fluids. Humans are made up of approximately 55 to 65% water, depending on gender, so water is necessary to survive. Water in and of itself is not toxic by any means, but rapid ingestion of a large quantity of water can dilute the careful balance of sodium compounds in the body fluids.
Our body has a balanced method of processing and excreting fluids, either through urine or perspiration. Over-diluting the sodium and potassium levels in the blood plasma through excessive consumption of water is called hyponatremia and contributes to what is called an osmotic shift of the fluid inside and outside the cells. The pressure from this action results in a swelling of the cells, often in the central nervous system, including the brain. This may result in water intoxication, which is not as serious as water poisoning, or as it is also called, hyperhydration.
When the cell membranes can no longer withstand the pressure, the cells can begin to die. This is indicated in more serious forms of water intoxication and water poisoning. Symptoms of this condition include lightheadedness, vomiting, headache, nausea and unresponsiveness. When the sodium in the blood plasma falls to dangerous levels, swelling of the brain, coma, seizures and possibly death may occur.
What constitutes a fatal amount of water can vary from person to person, depending on one's state of health, his or her physical activity at the time, the temperature and the amount of time in which the person consumes the water. For some, a one time consumption of six pints (three liters) can prove deadly. Although the person consuming the water may lose a lot of fluid due to perspiration during heavy labor or exercise, the electrolytes are not replaced fast enough to avoid water poisoning.
Those particularly at risk for water poisoning are athletes engaged in long distance running. Due to the need to replace large quantities of lost fluid, runners must drink a lot of water. This can lead to poisoning, so runners must replenish their fluids with sports drinks that have added electrolytes.
Other factors that contribute to water poisoning include the use of the drug ecstasy and hazing practices. Many “ravers,” while taking ecstasy, drink large quantities of water to avoid dehydration. Their reduced ability to reason can make this behavior dangerous. Many college students have been rushed to the hospital after consuming excessive amounts of water in hazing rituals. Psychiatric diseases can also lead to water poisoning. Psychogenic polydipsia is a condition in which the affected person feels a need to drink a lot of water for unknown reasons.
This condition is completely avoidable. For athletes, paying attention to how much water is consumed in one sitting, as well as using sports drinks to replenish lost fluids, is the best advice. When one feels thirst, the body is signaling dehydration, not an imbalance in electrolytes. It is commonly accepted among medical experts that it is more important to avoid dehydration than to attempt to avoid water poisoning. One should trust his or her instincts when drinking water and use common sense.