UNDERSTANDING OVERHYDRATION: WHEN TOO MUCH WATER CAN BE HARMFUL

Medically Reviewed by Dr. Sony Sherpa (MBBS) - July 17, 2024

Water is vital for every tissue in the body to function properly. It helps control body temperature, aids digestion, and carries nutrients to our cells. We have all heard the advice to drink eight glasses of water daily, but can drinking too much water be dangerous?

In this article, we will explore the concept of overhydration, its potential risks, and how to prevent it.

Understanding the Body's Water Balance

Our bodies comprise about 60% water^[1], and maintaining this balance is crucial for our health.

Water is vital in bodily functions like digestion, temperature regulation, and nutrient transport. It is also essential for optimal breathing and joint lubrication and to make waste elimination manageable for the liver and kidneys.

Our bodies regulate water balance through thirst cues, kidney filtration and hormonal output, fluid excretion, and distribution, maintaining a healthy equilibrium. The elimination of fluids and the concentration of electrolytes create an osmotic pressure gradient that directs water movement throughout the body. This process is known as osmoregulation.

The water we need to drink varies depending on age, activity level, and climate. For example, children need less water than adults, and people who are physically active, exercise regularly and live at higher altitudes or in hot climates may need to drink more water to stay hydrated.

From Hydration to Overhydration

While staying hydrated is essential for our health, it is possible to drink too much water.

Our body fluids can be categorized into two main compartments: intracellular fluid (inside cells) and extracellular fluid (outside cells). The intracellular fluid comprises the bulk of our body water, while the extracellular fluid makes up about one-third of the total body volume.

Our bodies tightly regulate water balance through a complex system involving the kidneys, antidiuretic hormone (ADH), and the osmoreceptor.^[2]

The kidneys play a substantial role in osmoregulation by filtering blood and controlling the amount of water reabsorbed from the glomerular filtrate (the fluid produced in the kidneys).

The hypothalamus, a brain region, is critical in regulating water balance. When it senses dehydration (high blood solute concentration), it triggers the release of ADH. ADH travels to the kidneys and signals them to reabsorb more water from the filtrate, reducing urine output. The hypothalamus also signals for thirst when we need water.

Conversely, when blood solutes are diluted due to excess water intake, ADH release is suppressed, and the kidneys excrete more water in the urine. The osmoreceptor in the throat is sensitive to blood volume and can also influence ADH release.

In severe cases, overhydration can result in a condition known as water intoxication or water poisoning. Water intoxication occurs when the body fails to excrete the excess water, causing cells to swell, including brain cells, which are sensitive to changes in body water balance. The kidneys can take the strain, and the blood can become overly diluted, leading to an electrolyte imbalance. Electrolytes are essential minerals that help balance body fluids and sustain nerve and muscle function.

Water intoxication can induce symptoms such as confusion, seizures, and even coma. In extreme cases, overhydration can be fatal.

When the sodium levels in the blood become critically low, overhydration can also cause hyponatremia. Hyponatremia interferes with the movement of fluids in and out of cells and can be life-threatening, as severe hyponatremia can exacerbate heart failure.

How Much Water Can the Kidney Handle?

Our kidneys can process about 800-1000 milliliters of water per hour. This means that if we drink more than this amount, our bodies may not be able to get rid of the excess water fast enough, leading to overhydration.^[3]

Risk Factors

While anyone can experience overhydration, certain factors can increase the risk. These include:

• Drinking excessive amounts of water in a short period
• Engaging in intense physical activity without replenishing electrolytes
• Having a medical condition that affects the body's ability to regulate water levels, such as kidney disease, heart failure, or a syndrome where the brain secretes too much ADH
• Psychogenic polydipsia, a psychiatric condition characteristic of compulsive water drinking^[4]
• Taking medications that contribute to water retention, such as nonsteroidal anti-inflammatory drugs (NSAIDs)
• Dehydration

Overhydration in Athletes

Athletes are at a higher risk of overhydration due to their intense training and the belief that they must drink large amounts of water to stay hydrated. However, this can be dangerous, especially during prolonged endurance events, where athletes may drink more water than their bodies can handle. This can lead to hyponatremia and even death.

Overhydration Symptoms: Mild to Severe

The symptoms of overhydration can range from mild to severe, depending on the level of water intake and the individual's overall health.

In the early stages, the body has time to adapt. Overhydration can lead to fatigue and a lowered ability to concentrate^[5]. Other symptoms include frequent urination and pale or transparent urine.^[6]

If overhydration occurs rapidly enough, symptoms may include:

• Nausea and vomiting
• Headaches
• Muscle cramps
• Difficulty maintaining balance
• Confusion
• Seizures
• Coma

While rare, overhydration can lead to death in severe cases.

When to Seek Medical Attention

If you experience any symptoms of overhydration, it is essential to seek medical attention immediately. This is especially important if you have been drinking large amounts of water or engaging in intense physical activity without replenishing electrolytes.

How Much Water Should One Drink?

The water we need to drink varies depending on age, body weight, climate, altitude, and physical activity levels. However, drinking more than 800-1000 milliliters of water per hour can put you at risk of overhydration.

Here are some general guidelines^[7]:

• Children aged 4-8 should drink about 1.2 liters of water per day, while children aged 9-13 should drink about 1.8 liters daily.
• A rough estimate is 3.7 liters (13 cups) for men and 2.7 liters (9 cups) for women. This includes fluids from beverages and food.
• Pregnant women may need up to 10 cups, while breastfeeding women may need up to 13 daily.
• People who exercise or live in hot climates may need more water. Drink roughly 1.5-2.5 cups of extra water if exercising.
• Those who live at an altitude higher than 8200 feet above sea level may also require more water per day to compensate for heat and radiation.

How Much Water Is Too Much for Athletes?

Athletes should aim to drink 500-600ml of water 2-3 hours before exercise and 200-300ml of water every 10-20 minutes during intense physical activity. Water consumption should still not exceed 800-1000ml per hour to avoid overhydration. According to studies, these precautions can help prevent dehydration and overhydration during training by providing a steady supply of fluids.^[8]

It is also essential to replenish electrolytes after every training session to avoid overhydration.

If drinking too much water during long endurance events due to overheating, find other ways to remain cool, such as wearing ice packs or a wet shirt.

Diagnosis

If you suspect you may be experiencing overhydration, your doctor will perform a physical checkup and may send for blood and urine tests to check your sodium and electrolyte levels. They may also ask about your medical history and any medications you are taking.

How to Fix Overhydration Immediately

If you are experiencing symptoms of overhydration, it is essential to seek medical attention immediately.

In the meantime, you can try the following steps to help alleviate symptoms:

• Stop drinking water and other fluids
• Rest and avoid physical activity
• Eat salty foods or drink sports drinks to replenish electrolytes
• Seek a medical consultation if symptoms persist or worsen

How to Treat Overhydration

The treatment for overhydration depends on the severity of the condition.

Reducing your fluid intake may be enough to restore the body's electrolyte balance in mild cases.

Additionally, treatment may require:

• Diuretics to help eliminate excess water
• Addressing underlying conditions related to overhydration
• Discontinuing medications that could lead to water retention
• Replenishing sodium and electrolytes in severe situations

In more extreme instances, the patient may require hypertonic saline solution administered intravenously with or without additional electrolytes.^[9]

Patients who are overhydrated for medical reasons, such as kidney failure, may need hospitalization and intensive care until they have fully stabilized.

How Long Does It Take to Recover from Overhydration?

The recovery time for overhydration depends on the condition’s severity and how quickly it is treated. In mild cases, symptoms can resolve within a few hours. In more severe cases, it may take several days to recover fully.

Keeping Yourself Hydrated the Right Way

The best way to prevent overhydration is to keep yourself hydrated correctly. Here are some tips to help you stay hydrated without overdoing it:

• Drink water regularly throughout the day rather than chugging large amounts at once.
• Pay attention to your body's thirst signals, and drink when thirsty.
• Replenish electrolytes during and after exercise, especially when engaging in intense physical activity.
• Avoid drinking excessive amounts of water, especially in a short time.

If you battle to keep track and find yourself overhydrating, you can download several hydration tracker apps that enable you to follow your hydration habits and moderate them if necessary^[10].

Advancements and Emerging Research

As our understanding of hydration and overhydration continues to evolve, researchers are exploring new ways to detect, prevent, and treat overhydration.

One advancement includes the development of wearable biosensor devices that can keep track of body electrolytes and sweat loss. These devices can estimate total body water loss and accurately alert users when to drink more water to maintain a steady fluid supply.

Preliminary trials suggest that they can keep track of changes in body water balance as precisely as conventional methods that measure changes in body weight before and after exercise and profuse sweating.^[11]

More testing is needed before such devices can become widely available.

Conclusion

While staying hydrated is essential for our health, it is possible to drink too much water. Overhydration can lead to serious health complications, including electrolyte imbalances and water intoxication. Seeking medical assistance right away is crucial if you exhibit any overhydration symptoms. By understanding the body's water balance and following proper hydration methods you can avoid overhydration.

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