Water may negatively affect the body when drinking more than normal amounts. Water is a vital component for the proper functioning of the body. It helps in a plethora of biological processes including digestion, absorption, and distribution of food and nutrients. Water helps maintain normal body temperature, protect the spinal cord, protect sensitive tissues, lubricate and cushion the joints, and excrete waste products through urination, bowel movements, and perspiration. It is also considered a natural detoxifier and is recommended for improvement of dermal conditions. Physicians and nutritionists always advise drinking a sufficient quantity of water.
Water intoxication results from drinking too much water. Doing so increases the amount of water in the blood. The excess water dilutes sodium in the blood and causes fluids to move inside cells, causing them to swell. This can dilute the electrolytes, especially sodium, in the blood. Hyponatremia occurs when the concentration of sodium in your blood is abnormally low. Sodium helps maintain the balance of fluids inside and outside of cells. When sodium levels drop due to excessive water consumption, fluids travel from the outside to the inside of cells, causing them to swell. When this happens to brain cells, it can be dangerous and even life threatening.
Most cells have room to stretch because they are embedded in flexible tissues such as fat and muscle, but this is not the case for neurons. Brain cells are tightly packaged inside a rigid boney cage, the skull, and they have to share this space with blood and cerebrospinal fluid. Inside the skull there is almost zero room to expand and swell. Thus, brain edema, or swelling, can be disastrous. Rapid and severe hyponatremia causes entry of water into brain cells leading to brain swelling, which manifests as seizures, coma, respiratory arrest and brain stem herniation. The direct cause of death by water intoxication is often brain oedema.
Excessive Intake of Water
Overhydration due to excessive water intake may occur for a number of reasons. These can include consumption of large or inappropriate amounts of water due to the belief that it supports good health, rapid hydration following dehydration, drinking competitions, the use of water during child abuse, hazing, torture, or other abuse, excessive drinking of fluids in preparation for medical testing, such as colonoscopy, polydipsia, a condition in which a person has a persistent feeling of thirst, causing them to drink too many fluids.
Polydipsia can occur as a result of psychiatric conditions such as psychotic depression, bipolar disorder, or schizophrenia, conditions that affect the hypothalamic region of the brain such as infection, inflammation, or infiltration (leaking), certain medications and recreational drugs.
Drinking water after intense or prolonged exercise can also lead to water intoxication. This happens because it replaces water in your body without correcting for lost electrolytes. Electrolytes are a type of solute, which includes sodium.
Infants can also experience water intoxication if caregivers give them too much. Young infants do not need water and can meet their fluid needs from breast milk or formula. Diluting breast milk or formula with water can be dangerous. Additionally, submerging infants in water such as during swimming lessons can cause them to gulp excess water.
Impaired Excretion of Water
Overhydration can also occur if your body is not able to excrete water sufficiently. This can happen due to impaired kidney function, congestive heart failure, cirrhosis of the liver, Addison’s disease or hypothyroidism.
Syndrome of inappropriate antidiuretic hormone secretion (SIADH) is a condition in which the body makes too much antidiuretic hormone (ADH). This hormone helps the kidneys control the amount of water your body loses through the urine. SIADH causes the body to retain too much water. The most common causes of SIADH are pulmonary disorders, CNS disorders, medication, intense exercise, physical stress and infection.
Symptoms of Water Intoxication
Symptoms of water intoxication tend to start appearing after you consume more than 3 to 4 L of water in a few hours. Potential symptoms include head pain, cramping, spasms, or weakness in your muscles, nausea or vomiting, drowsiness and fatigue.
Severe cases of water intoxication can produce more serious symptoms, such as drowsiness, muscle weakness or cramping, increased blood pressure, double vision, confusion, inability to identify sensory information and difficulty breathing. In more severe cases, water intoxication can also cause seizures or loss of consciousness.
Water intoxication can be prevented if a person's intake of water does not grossly exceed their losses. Healthy kidneys are able to excrete approximately 800 millilitres to one litre of fluid water per hour. However, stress (from prolonged physical exertion), as well as disease states, can greatly reduce this amount.
Avoid situations that provoke extreme or prolonged perspiration. Drinking fluids that are specially balanced to replace lost electrolytes can also help to prevent intoxication. Eating regularly can provide needed electrolytes if only normal water is available for rehydration.
Sports drinks are popular among athletes because they provide the necessary electrolytes to support extended exercise. They help keep the body balanced and carry the right amount of fluids. However, not all drinks advertised as sports drinks are suitable for this purpose, and professional advice should be sought for potentially risky situations.
Note that a person's innate sense of thirst is more sensitive to overall dehydration than to changes in electrolytes. Thus, it is possible to develop water intoxication while trying to satisfy thirst if one drinks a great deal of water over a short period. A dangerous drop in electrolytes, such as the hyponatremia that leads to water intoxication, will not have any effect on thirst if one is sufficiently dehydrated.
For people suffering from dehydration due to the heavy perspiration associated with heavy exertion or heat stress, drinking water to rehydrate is much more important than avoiding water intoxication, since the former is extremely common and the latter is rare. One should never avoid drinking water under such conditions; instead, other steps should be taken to ensure that electrolytes are replaced as well.