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What happens if I drink too much water?

Water is essential for life, but drinking too much can cause dangerous side effects. This article examines what happens if you drink excessive amounts of water.

Can you drink too much water?

Yes, it is possible to drink too much water. Consuming excessive amounts of water is also known as water intoxication or overhydration.

While guidelines vary, most experts recommend drinking about 15.5 cups (3.7 liters) of water per day for men and about 11.5 cups (2.7 liters) per day for women. Drinking significantly more than this over a short period of time can cause water intoxication.

What causes water intoxication?

Your kidneys are responsible for maintaining fluid balance in your body. They can typically excrete 800 to 1,000 ml of water per hour. If you drink more than this, the excess water cannot be excreted and dilutes the sodium levels in your blood.

This causes an imbalance of water and electrolytes in your body, which can lead to swelling in the brain and other serious symptoms. Conditions that may increase your risk of water intoxication include:

  • Endurance sports – Drinking too much water before, during, or after prolonged exercise can cause hyponatremia (low blood sodium). This is especially common in marathon runners.
  • Kidney problems – Damaged kidneys may not be able to excrete excess water effectively.
  • Psychiatric conditions – Those with conditions like schizophrenia may compulsively drink too much water.
  • MDMA use – Taking “ecstasy” or MDMA may cause you to consume dangerous amounts of water.

Early symptoms

The early symptoms of drinking too much water typically come on within 30 minutes to a few hours after overhydration. They include:

  • Headache
  • Dizziness
  • Nausea
  • Vomiting
  • Confusion
  • Muscle cramps
  • Fatigue

These symptoms are caused by fluid overload and the resulting electrolyte imbalance. They tend to be more common after rapidly drinking a large amount of water on an empty stomach.

Severe symptoms

As excess water continues to build up in the body’s tissues and dilute sodium levels further, more dangerous symptoms can develop. These include:

  • Irritability
  • Disorientation
  • Slurred speech
  • Seizures
  • Coma
  • Brain swelling (cerebral edema)
  • Lung swelling
  • Death in severe cases

Severe water intoxication leads to electrolyte imbalances that can disrupt normal brain and lung function. Immediate emergency medical treatment is critical at this stage.

How much water is too much?

There is no single amount of water that is guaranteed to cause water intoxication, since it depends on your body mass, kidney health, and rate of intake. However, some general guidelines for when water intake may be excessive include:

  • Drinking over 1 liter per hour for several hours
  • Consuming over 3-4 liters in a 24-hour period
  • In athletes, drinking well beyond sweat losses during exercise

Drinking these amounts over a short time span allows little chance for the kidneys to excrete the excess water. Certain conditions like kidney disease or medications may also lower the amount needed to cause intoxication.

Who is at risk?

Those most at risk of hyperhydration tend to include:

  • Endurance athletes
  • Hikers or laborers in hot climates
  • People with psychiatric conditions
  • MDMA/ecstasy users
  • People with kidney disease or using diuretics
  • Infants and young children

However, even healthy adults can develop water intoxication if they consume too much water too quickly.


To avoid drinking too much water:

  • Drink when thirsty rather than on a schedule
  • Avoid drinking over 1 liter per hour
  • Limit fluid intake during exercise to match sweat losses
  • Eat salty foods to replace lost sodium
  • Avoid using MDMA or other illicit drugs
  • Treat underlying psychiatric disorders

Monitoring your urine color can also help. A light lemonade color is ideal, while clear urine may indicate overhydration.


Treatment for water intoxication focuses on managing symptoms and restoring normal electrolyte levels, especially sodium. This may involve:

  • Stopping any further water intake
  • Intravenous fluids and electrolytes
  • Medications to reduce brain swelling
  • Seizure medications
  • Kidney dialysis in severe cases

With prompt treatment, most cases of water intoxication can recover fully. However, delaying treatment can lead to life-threatening brain swelling, seizures, coma, and death in rare cases. Seek emergency medical care if you suspect water intoxication.

Preventing excess water intake is always better than treating water intoxication after the fact. Be sure to drink water in moderation, avoid overhydrating during exercise, and monitor your urine concentration.


Drinking too much water, known as water intoxication or hyperhydration, can cause dangerously low sodium levels and fluid overload. Early symptoms like headache, nausea, and fatigue typically come on within 30 minutes to a few hours of overhydrating.

As excess water continues to build up, it can lead to severe and potentially fatal symptoms like seizures, brain swelling, coma, and lung swelling. Those most at risk include endurance athletes, people with psychiatric disorders, and those with kidney problems.

While recommendations vary based on your health and activity level, drinking over 1 liter per hour or 3-4 liters per day is generally considered excessive. Preventing water intoxication through moderation and smart hydration practices is key. Seek emergency medical treatment immediately if severe symptoms of overhydration occur.