Dehydration vs. Overhydration: Why Drinking More Water Isn't Always Good For You

Drinking too much water can cause water intoxication or water poisoning. This can lead to seizures and even death.

Dehydration and overhydration are two sides of the same coin.

(Image: Namita Chauhan/Quint Fit)

With heatwaves searing through India, scorching the earth and turning people into kebabs, it's hard to overstate the importance of staying hydrated.

Water is essential, mostly because the human body is 70 percent water. Dehydration can come on very quickly in the heat, and with the temperature currently set to the fifth circle of hell, you need to drink all the juices, water, electrolyte drinks, and beverages you can get your hands on.

But while dehydration lies on one end of this spectrum, overhydration lies on the other end.

Overhydration is a condition that happens when you either consume unreasonably large amounts of water in a short period, or if your kidneys can't process the water you're drinking as quickly as you're drinking it.

Overhydration can lead to confusion, dizziness, nausea, and a condition called water intoxication or water poisoning.

So, while dehydration is bad for you, overhydration can be just as bad, if not worse. Today we'll try and help you understand more about overhydration and the dangers of drinking too much water.

What Is Overhydration?

Overhydration happens when you drink much more water than your body needs or much more water than your kidneys can safely excrete.

This results in an extreme imbalance of sodium and other essential electrolytes in your body, and conditions like hyponatremia and water poisoning.

Hyponatremia is the dilution of sodium in your blood to abnormally low levels because of an excess of water. Sodium regulates the amount of water in and around your cells. When it falls, you can suffer a range of complications including:

• Headaches

• Confusion

• Nausea

• Muscle cramps

• Restlessness

• Fatigue

If left untreated this can quickly escalate to more serious complications like seizures and even a coma.

What Causes Overhydration and Water Poisoning?

Water poisoning and hyponatremia don't often happen naturally because of drinking water. In many instances, water poisoning is caused by drinking large quantities of water in water-drinking competitions or military training.

"You don't often see cases of water poisoning. It's far less common than instances of dehydration," says Shayamal Vallabhjee, Sports Scientist and Performance Coach.

Water poisoning is also seen often in soldiers in military training.

A study from the US army found that three trainees had died from water poisoning, while 17 more soldiers were hospitalized over the period of a year for water intoxication.

Overhydration can happen for a few other reasons as well:

Overhydration during intense exercise

Like water poisoning during military training, overhydration during intense heat or exercise can lead to a fall in sodium reserves in your body.

The combination of heavy sweating combined with drinking just water, rather than a drink that replenishes lost electrolytes, can lead to water intoxication.

Heat-related Overhydration

When temperatures rise, we sweat to cool our bodies off. You also lose more fluids when you sweat, which increases thirst.

Thirst leads to drinking water. But with the heat crossing 40 degrees celsius, the urge to constantly drink water is overwhelming. But after a certain point, you've lost so many electrolytes and fluids through the sweating that drinking more water is actually diluting your electrolytes even further.

This can lead to headaches, irritability, confusion, and in some cases, water poisoning.

Kidney Disease

If you suffer from chronic kidney disease or other kidney problems it can lead to fluid build-up in your body. Your kidneys can expel approximately half a litre of fluid every hour, says Dr. Amit Varma, ER Specialist.

When you drink excess water, your kidneys can't expel the excess fast enough, and this leads to the dilution of sodium reserves. This is made worse if you suffer from kidney disease. This results in cramps, nausea, dizziness, and eventually water poisoning if untreated.

Use of Amphetamines like MDMA

The use of amphetamines like MDMA(commonly called E, ecstasy, candy) can lead to exertion, heavy sweating and extreme thirst. This leads to overhydration in many cases.

Combined with the increased physical activity and MDMA decreasing the amount of water you lose through urination, it can quickly lead to electrolyte dilution, water poisoning and even death.

Psychogenic Polydipsia

Psychogenic polydipsia is a mental disorder that leads to excessive consumption of water. It's also commonly called self-induced water intoxication. In this condition, a patient starts by drinking excessive amounts of water. This continues until the patient in question suffers water intoxication. If left untreated, this disorder can quickly turn fatal or leave the patient in an extremely dangerous state.

Forcefully drinking water to an excess leads to all the problems we've mentioned above - nausea, cramps, confusion, and even seizures.

Intravenous Fluid Delivery

If you're hospitalised and hooked up to an IV drip to give you your fluids, the formulation you'll be given will be a carefully balanced combination of electrolytes, fluids, and other essential vitamins. In the absence of the correct combination of fluids and electrolytes, you can quickly suffer from fluid intoxication. Additionally so because you can't consciously regulate how much you're drinking.

How To Avoid Overhydration and Water Intoxication

Simply said, don't drink an excess of water. But that's not too helpful. So, if you're spending a lot of time in the heat, or if you're exerting yourself heavily, ensure you drink water, but ALSO ensure you drink electrolyte drinks like coconut water, buttermilk, oral rehydration solution, lemon juice with salt and sugar, and pay attention to how you feel.

If you feel a headache coming on, and you're drinking a lot of water, switch to drinking electrolyte drinks and get yourself into a cool, comfortable place.

Alternatively, stop drinking water and have salt water or just salt instead.

All of these are simply temporary measures, however, and you need to get yourself to a doctor if you suspect you may have water intoxication or water poisoning.

The problem is, both dehydration and overhydration can display similar symptoms in people - so if you think you're dehydrated and actually overhydrated, drinking more water is very dangerous.

Needless to repeat, visit a medical expert if you think you're suffering from water intoxication. Also check out our video on water intoxication and overhydration here.

(This story was first published in April 2022. It has been republished from FIT's archives after a new study, published in the Clinical Kidney Journal, claimed that martial artist and actor Bruce Lee's death, back in 1973, was caused by hyponatraemia.)