What is water intoxication definition?
Water intoxication or poisoning is a life-threatening condition caused by excessive water drinking that results in a drop of blood sodium levels (1). Drinking as little as 2 liters of water per hour for few successive hours can result in water intoxication.
Water intoxication does not likely occur by accident but by conscious exaggeration, such as by drinking several liters of water in few hours or more than 10 liters per day.
Symptoms and signs of water intoxication in adults can include headache, vomiting, swelling of the hands and feet, confusion, seizures, coma or even death.
The medical term for water intoxication is dilutional hyponatremia. Synonyms include water overdose and water poisoning.
Acute and Chronic Water Intoxication
By definition, in acute water intoxication, blood sodium level drops under 130 mmol/L within 48 hours, and in chronic intoxication in more than 48 hours (18,47,52).
Symptoms and Signs
First symptoms of water intoxication can appear when the blood sodium levels fall below ~130 mmol/L and can include:
- Nausea, vomiting or diarrhea
- Restlessness, irritability
- Lightheadedness, dizziness
- Difficulty concentrating
- Fatigue, muscle weakness, unstable gait
- References: (1,16,24,45)
NOTE: Clear urine by itself is not already a symptom of water intoxication; you can excrete clear urine when you are normally hydrated or overhydrated.
Late Symptoms (Severe Water Intoxication)
The following symptoms may develop from several hours to few days after the onset of the first symptoms, when the blood sodium levels fall below ~105 mmol/L:
- Muscle cramps, tremor, shaking
- Swelling of the hands and feet, or abdomen (ascites), especially in alcoholics
- Drowsiness, blurred vision
- Confusion, unusual behavior, agitation, hallucinations, delirium
- Coughing up blood (due to lung edema)
- Less urination than expected from the fluid intake (38)
- Seizures (convulsions): jerky limb movements, unusual grimacing
- Death, usually within 1-2 days after onset of symptoms
- References: (1,16,24,28,38)
The faster the drop of the sodium levels, the more severe the symptoms (1).
- Sudden increase of the body weight (up to several kilograms), but not always; for example, a person who is initially dehydrated and drinks a lot of water can still be dehydrated and thus has lower than normal body weight, but may already suffer from water intoxication (29).
- Dilated pupils on both sides
- Slow heart rate (bradycardia)
- Increased frequency of breathing (in pulmonary edema) or decreased frequency and volume of breathing (in respiratory arrest)
- Bluish discoloration of the lips and hands (cyanosis due to pulmonary edema)
- Decreased (hypotension) or increased blood pressure (hypertension)
- Rigid posture with arms bent inward toward the body and hands held on the chest, clenched fists, and legs held out straight (decorticate posture)
- References: (24,48,55,58)
Short-Term Effects on the Body Organs
- Brain swelling (cerebral edema)
- Lung swelling (pulmonary edema)
- Muscle breakdown (rhabdomyolysis)
An episode of a severe hyponatremia may leave a person with a permanent brain damage resulting in:
- Mental retardation
- Diabetes insipidus
- Persistent vegetative state
- Hearing loss
- Cerebral palsy
- Gait abnormality
- References: (17,29,54,55)
Causes and Risk Factors
The cause of water intoxication is drinking excessive amounts of water or other beverages that contain little or no sodium, such as tea, coffee, fruit juices, soft drinks, beer and even sport drinks in combination with low sodium intake from foods.
Factors that increase the risk of water intoxication:
- Female sex
- Low body weight (infants, children, small women)
- Low sodium intake (fasting, starvation)
- Poorly controlled diabetes mellitus with ketoacidosis (55)
- Certain drugs (see below)
Water retention due to (29):
- Syndrome of inappropriate (excessive) secretion of the antidiuretic hormone (SIADH) in which kidneys are not able to excrete excessive fluid; causes include severe pain, stress, prolonged hard exercise (marathon), surgery, cancer or certain brain or lung disorders or drugs.
- Heart failure, kidney failure, nephrotic syndrome (a kidney disorder with protein loss in urine), malnutrition with poor protein intake (kwashiorkor), and other causes of hypoproteinemia, liver cirrhosis, hypothyroidism, adrenal insufficiency (Addison’s disease).
- Nephrogenic syndrome of inappropriate antidiuresis (NSIAD) — a rare genetic disease in male infants (55)
- References: (13,43,48,55)
Overhydration along with low sodium intake results in a drop of blood sodium levels (hyponatremia), which in turn results in a drop of blood osmolality. According to the principles of osmosis, water then moves from the space with lower into the space with higher osmolality, that is from the blood into the body cells, including the brain cells, which swell. Brain swelling (cerebral edema) causes the brain to get compressed within the tight skull, which is the main cause of symptoms of water intoxication and, eventually, death.
Examples of Water Intoxication (Media and Medical Case Reports)
1. Water Intoxication in Infants
Water intoxication due to diluting baby formula or treating diarrhea in sick infants with plain water is described here.
2. Child Abuse
Forced water drinking is a form of punishment of children (7).
- In 2002 in Utah/USA, a 4-year old girl died after her parents forced her to drink about a gallon (3.8 liters) of water within few hours (32).
- In 2002, in Florida/USA, a babysitter forced a 3-year old girl to drink 3 quarts (2.8 liters) of water in 4 hours. The girl died the next day (33).
3. Water Drinking Contests and Games
- People have died after drinking water in amounts such as 7.5 liters in few hours in water contests (11) and fraternity hazes in colleges (10).
- In 2012 in Sweden, a 12-year old girl died after drinking 6 liters of water within few hours of playing poker (every player had to drink a glass of water for every lost game). She died few days later (51).
4. “Water Diet” for Weight Loss
An attempt to lose weight quickly with a combination of very restricted diet and hence low sodium intake and drinking large amounts of water to suppress the appetite can result in fatal hyponatremia.
- In 2008, in England, a 40-year old woman was on a calorie-restriction diet during which she was consuming very little salt but drinking a lot of water. One day, after about 1 week of her diet, she drank about 4 liters of water in less than 2 hours and then developed severe headache, collapsed and lost consciousness. She died in the hospital the next day (26).
5. Exercise-Associated Hyponatremia (EAH) and Encephalopathy (EAHE) in Marathon or Triathlon Runners
Runners can develop hyponatremia if they drink excessive amounts–typically more than 1.5 liter per hour–of water or other beverages, including most commercial sport drinks that contain insufficient amount of sodium (14,29).
Other causes and risk factors for exercise-associated hyponatremia (29):
- Hard exercise lasting more than 4 hours
- Hot weather, which means more sweating and hence more drinking
- Athletes, especially women, with low body weight, high sweating rates and high salt losses in sweat
- Taking non-steroidal anti-inflammatory drugs (NSAIDs), such as indomethacin or ibuprofen, which stimulate water retention and sodium loss with the urine (19). Acetaminophen is considered safe in this regard (46).
Cases of death due exercise-associated hyponatremia:
- In the 2002 Boston marathon, a 28-year old woman died due to excessive drinking of a commercial sport drink (34).
- In 2005, in Washington DC/USA, a 25-year old man died a day after drinking 3 gallons (11.4 liters) of water during and after a 12-mile bike ride (35).
6. Overhydration in Heat-Related Illness
- In 1996-97, several US soldiers suffered from hyponatremia with confusion, nausea, vomiting or seizures after drinking 2 or more liters of water in an attempt to avoid heat stress (31).
7. Attempt to Hide Drug Abuse
In attempt to dilute urine samples for drug testing, some individuals drink large amounts of water on the day before testing (4,41). Such urine has low specific gravity, which can be easily identified during testing, so cheating is not likely effective.
- In 2003, a 43-year old man drank 5 gallons (19 liters) of water along with 20 capsules of a diuretic Uva ursi or bearberry (which probably stimulates sodium excretion) over few hours before drug testing (he was recently smoking marijuana) (42). He was lethargic but had no seizures. He was treated successfully with an intravenous infusion of 3% saline.
8. Psychogenic Polydipsia or Compulsive Water Drinking
Some individuals with schizophrenia or other mental disorder can drink up to 15 liters of water per day. This is called compulsive water drinking or psychogenic polydipsia.
- In 1980, 20 individuals with schizophrenia and psychogenic polydipsia lasting up to 28 months were evaluated for hyponatremia due to drinking 7-43 liters (!) of water per day (36). Their blood sodium levels ranged from 98 to 124 mmol/L (normal levels are 135-145 mmol/L).
Beer contains very little sodium, so excessive beer drinking with poor food and hence sodium intake can result in hyponatremia (37,38). Chronic alcoholics also often have protein malnutrition. Low blood sodium levels result in low osmotic pressure and low protein levels in low oncotic pressure of the blood, which results in the movement of water from the blood into the brain cells (brain edema) and in the body cavities (distended abdomen or ascites).
- In one case from 2012, a man in his thirties, was drinking at least 10 liters (more than thirty 12-oz cans) of beer per day and eating nothing for few days. He became confused but remained conscious; during examination, his hands were shaking and his abdomen was distended. His blood sodium level was 105 mmol/L (normal = 135-145) and blood serum osmolality was 225 mOsm/kg (normal = 280-300). Urine osmolality was less than 1.005 (normal = 1.010-1.025).
10. Suicide Attempt
Some people have tried to kill themselves by drinking large amounts of water.
11. Intravenous Infusion of Hypotonic Fluids (Containing No or Little-Sodium)
An intravenous infusion of a hypotonic fluids, which contain less sodium than the blood, such as 5% dextrose in water (DW5 or D5W), can lead to hyponatremia (53). After surgery, the release of the antidiuretic hormone (ADH) is often increased, which results in water retention but normal sodium excretion; this means that an individual who receives intravenous infusion after a surgery can develop hyponatremia (19).
12. Gastric Lavage
Gastric lavage with large amounts of plain water may result in water absorption and hyponatremia (5,39).
- As reported by Forensic Science International journal in May 1995, an 21-year old woman died after gastric lavage with 7.8 liters of water within 2 hours (40).
- Enema using tap water can cause dilutional hyponatremia, especially in infants, children and elderly (49).
- Cleansing of the colon with water before barium enema can also cause water intoxication (50).
- A 3-year old boy developed hyponatremia after colon irrigation with plain water (56).
14. Transurethral Resection of Prostate (TURP) Syndrome
Water absorbed from irrigation during endoscopic prostate resection or, rarely, during other endoscopic procedures (cystoscopy, percutaneous nephrolithotomy, arthroscopy) can result in, sometimes fatal, hyponatremia within 15 minutes to 24 hours after the procedure (12).
In certain disorders, the antidiuretic hormone (ADH), which prevents water loss from the body by inhibiting urination, is secreted in excessive amounts despite normal hydration, which results in water retention and hyponatremia. This is called syndrome of inappropriate ADH secretion or SIADH. Common causes of SIADH include certain brain and lung disorders, cancers and medications (chemotherapeutics, an antiepileptic drug carbamazepine) (8,25).
16. Cystic Fibrosis
Individuals with a rare genetic diseases cystic fibrosis lose excessive amounts of sodium in sweat so they are more prone to develop hyponatremia after drinking water.
Medications that stimulate water retention and/or sodium excretion, which can both result in hyponatremia, when taken with excessive amount of water (6,43):
- Anticonvulsants (antiepileptics), such as sodium valproate, carbamazepine, phenytoin
- Antidepressants (SSRIs, TCAs, monoamine oxidase inhibitors).
- A 82-year man who was taking a tricyclic antidepressant (mirtazapine) and ACE inhibitor (ramipril), got confused several hours after drinking 3 liters of water over 4 hours in preparation for an urine-flow study (43). In the hospital, hyponatremia was diagnosed and successfully treated.
- Antidiabetics: chlorpropamide
- Antipsychotics, such as haloperidol
- Chemotherapeutics, such as vincristine
- Cholesterol-lowering drugs, such as clofibrate (44)
- Desmopressin spray (an analog of the hormone ADH), a drug used to treat bed wetting (enuresis) in children (6).
- Diuretics, such as thiazides, indapamide, furosemide
- Opioids, such as morphine
- Other: ACE-inhibitors (lisinopril, losartan), amlodipine, proton-pump inhibitors (omeprazole), amiodarone, and the antibiotics, such as trimethoprim-sulfamethoxazole and ciprofloxacin
18. Ecstasy (MDMA) or Amphetamine Use
People who take stimulant drugs, such as ecstasy or amphetamine, can dance for several hours without rest, so they can lose a lot of water and sodium with sweat. These drugs can stimulate thirst and secretion of the antidiuretic hormone and hence water retention, which can, in combination with excessive drinking, result in hyponatremia (19).
- Several young people have died after taking ecstasy, dancing and drinking various amount of water (up to 7 liters within 1.5 hours) afterwards (15,30).
CHART 1: Health conditions with similar symptoms as water intoxication (23)
|Water Intoxication||Headache, vomiting, increased urination, confusion, unsteady gait, agitation, seizures, coma||Swelling of the hands and feet, dry or sweaty skin, normal skin turgor, normal or increased body weight, clear urine|
|Severe dehydration||Thirst, nausea, headache, fatigue, confusion, coma||Dry skin, prolonged skin turgor, decreased body weight (>5%), decreased urination, dark urine|
|Heat exhaustion||Thirst, headache, fatigue||Pale, cool and sweaty skin, increased, increased breathing and heart rate, body T (37-40 °C)|
|Alcohol intoxication||Unsteady gait, disorientation, vomiting, fatigue, coma||Alcohol odor|
|Gastroenteritis||Diarrhea, vomiting, abdominal cramps||Signs of dehydration|
|Adrenal insufficiency or crisis||Fatigue, weight loss, skin pigmentation, abdominal pain, salt craving|
|Nephrotic syndrome||Fatigue||Foamy urine, general body swelling (edema)|
|Kidney failure (acute or chronic)||Anorexia, nausea, vomiting, fatigue, changes in urine volume||Body swelling (edema)|
|Syndrome of inappropriate ADH secretion (SIADH) 59||Nausea, headache, weakness||Normal blood pressure, no edema|
|Cerebral salt-wasting syndrome||Headache, lethargy, agitation|
|Left heart failure with lung edema||Fatigue, chest pain, weakness, difficulty breathing (dyspnea)||Increased breathing rate, decreased breathing sounds during auscultation|
|Hypothyroidism (myxedema coma)||Fatigue, feeling cold||Cool, dry skin, swelling, especially in lower legs, increased body weight, decreased body temperature|
|Liver cirrhosis||Nausea, fatigue||Abdominal swelling (ascites)|
Diagnosis, Lab Tests
- Low sodium levels (<135 mmol/L)
- Other electrolytes are usually within normal ranges
- Low osmolality (<275 mOsm/kg)
- Reference: 38
- Low sodium; in SIADH: high sodium (>20 mmol/L)
- Low osmolality (<100 mOsm/kg); in SIADH high osmolality (>1,200 mOsm/kg)
- Low specific gravity (<1.010); in SIADH high osmolality (>1.032)
- References: 8,20,38
Magnetic Resonance (MRI):
- MRI can reveal brain swelling (55)
In an individual with severe headache, vomiting or seizures, it is important to differ between dehydration and overhydration: A severely dehydrated person will always have significantly reduced body weight (>5% loss of b. w.) and, usually, prolonged skin turgor. An overhydrated person can have normal or increased body weight or, after prolonged exercise, even slightly reduced weight, and, occasionally, swollen hands and feet. What to do to an overhydrated person:
- If agitated, try to calm him or her down.
- Do not give him or her anything to drink or eat.
- Call an ambulance (in the U.S.: 911).
Treatment of water intoxication with severe symptoms, such as seizures, may include water and salt restriction (in hypervolemia), salt tablets (in hypovolemia) (27), high-protein diet, intravenous fluid infusion (usually hypertonic 3% saline), diuretics (furosemide), arginine-vasopressin (AVP, ADH) antagonists (demeclocycline, conivaptan, tolvaptan) and anticonvulsants (antiepileptic drugs) (18,21,22,27,57).
Chronic hyponatremia should be treated slowly — blood sodium levels should rise slower than 0.5 mmol/L/hour, otherwise serious neurological complications, such as central pontine myelinolysis, can develop (47).
Water intoxication can be usually treated successfully without consequences.
Bad prognostic factors:
- Blood sodium levels below 105 mmol/L (mortality up to 50%) (18)
- Pulmonary edema (29)
- Pneumococcal meningitis (55)
- Hypoxia (61)
- Women in childbearing period (61)
- During marathon, triathlon or other endurance event, drink only to thirst, have salty snacks, avoid NSAIDs from 24 hours before to 6 hours after the race (28).
- During few days before marathon and on the day after marathon, eat regular salty foods to build up sodium stores in your body. Do not try to overhydrate yourself before marathon (28).
- Salt tablets during the race are not recommended because they affect blood sodium levels too quickly and may cause stomach cramps.
Frequently Asked Questions
What is the safe amount of water you can drink in a day?
A healthy adult on an average diet with usual salt consumption can drink up to about 11 liters of water in a day, if needed (9).
A healthy adult who eats nothing or very little (fasting, starving) and hence consumes no or very little salt can safely drink up to about 5 liters of water per day.
How much water is safe to drink in one hour?
The adult kidneys can excrete 0.7-1 liter of water per hour, so this is the amount that can be assumed as safe to drink in one hour. According to Current U.S. Military Fluid Replacement Guidelines, a person should not drink more than 1.4 liters of water per hour (9).
Are there any benefits of drinking excessive amounts of water?
There are no known benefits of drinking water in excess of the body needs. It is not clear if drinking large amounts of water helps prevent kidney stones in individuals with a personal or family history of kidney stones.
Is water intoxication painful?
People who consider to make a suicide usually ask this question. Severe water intoxication is usually accompanied with severe headache, nausea, vomiting, exhaustion and seizures. Severe hyponatremia caused by water overdose, or even treatment of hyponatremia can lead to permanent neurological disability.
What is the difference between hyperhydration and overhydration?
The term hyperhydration is usually used for excessive amount of water in the body and is just the opposite of dehydration. A hyperhydrated person usually has some form of body swelling (generalized edema, edema in the legs, edema in the abdominal cavity or ascites).Hyperhydration may be present with or without hyponatremia.
The term overhydration is usually used for drinking of excessive amount of water in a short time resulting in water intoxication and hyponatremia. Someone who overhydrates him/herself can become hyperhydrated, normally hydrated or remain dehydrated (if dehydrated at the start of drinking). For example, a dehydrated marathoner who quickly drinks excessive amounts of plain water after the race may still be dehydrated but already having hyponatremia due to overhydration.
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