The horrible ways drinking too much water affects your brain and body

• Drinking too much water too quickly can lead to a dangerous condition called water intoxication.
• Water intoxication causes neurological symptoms including confusion and seizures.
• There's no specific amount of water that is too much, it depends on factors like age and overall health.
• Visit Insider's Health Reference library for more stories.

Drinking water is essential to keeping the body healthy and functioning properly. However, there's such a thing as drinking too much water too fast, aka water intoxication.

Water intoxication occurs when you drink so much water that the kidneys can't eliminate it fast enough, so it begins to dilute electrolytes — primarily sodium — in the blood. 

Although it's rare, water intoxication can lead to death if not treated immediately.

Here are the symptoms of water intoxication and how it is generally treated.

How much is too much water?

Water intoxication is a dangerous and severe condition because blood sodium levels drop rapidly, causing neurologic changes like hallucinations and confusion.

Adults need to drink about 2.7 to 3.7 liters of fluids a day, which will come from water, food, and other beverages.

Water intoxication may occur from drinking more than three to four liters of water over a short period, like one or two hours, says Lewis Nelson, MD, chair of emergency medicine at the Rutgers New Jersey Medical School.

No specific amount of fluid is considered unsafe, however, and the risk of water intoxication will vary depending on the frequency of intake, age, sex, and overall health.

Symptoms of water intoxication

Water intoxication is primarily a neurological syndrome, says Nelson. Too much water may make the brain swell and disrupt normal functioning.

The early symptoms of water intoxication may include the following:

• Headaches
• Confusion
• Nausea
• Vomiting
• Forgetfulness

If not treated immediately, it may lead to other symptoms, such as:

• Slurred speech
• Weakness
• Hallucinations
• Muscle cramps
• Impaired brain functioning
• Seizures
• Coma

Water intoxication tends to occur among adults who run marathons, do military training, and have mental health conditions like psychogenic polydipsia (aka compulsive water drinking) or schizophrenia. However, it can also develop in babies.

Infants younger than six months are not allowed to have water because they have small bellies and their kidneys are not yet developed. If they are given water or their baby formula is over-diluted, they may experience water intoxication. Symptoms include vomiting, irritability, weakness, and seizures.

How to treat water intoxication

Water intoxication can be lethal, and it must be treated immediately.

"Patients with water intoxication have a medical emergency and should be brought to the hospital for emergent medical care. We would typically need to stop their seizures, infuse concentrated sodium-containing solution, and support their breathing," says Nelson.

You will need intravenous electrolyte solutions and other medications to restore normal blood sodium concentration. The mortality rate for patients with water intoxication is about 7.1%.

Insider's takeaway

Water intoxication occurs when you drink too much water to the point that you dilute the sodium concentration in your blood. It can cause neurological symptoms such as weakness, seizures, or impaired brain functioning.

To treat water intoxication, you would need intravenous fluids to increase sodium levels in the blood.

"If you suspect someone has severe water intoxication with features such as obtundation [or a reduced level of alertness], seizures, coma, or others, call 911 for emergency assistance," says Dennis Moledina, MD, Yale Medicine nephrologist and assistant professor at the Yale School of Medicine.