We all know water’s vital role in physical well-being—from giving your skin its glowing complexion to boosting your energy levels. And it’s no secret that staying hydrated is essential for optimal health and several bodily functions, like supporting digestion, regulating body temperature, and facilitating nutrient transport. 

But scrolling through social media, you might be flooded with health messaging suggesting other supposed miracles of drinking lots of water, such as flushing your system of “toxins.” But can drinking too much water actually be bad for you?

To answer this compelling question, we spoke with experts who reveal the side effects, symptoms, and risks of overhydrating, as well as share advice for treating and preventing them. Read on to learn more.

What is Water Intoxication?

Water intoxication, also known as water poisoning, is a condition that arises when you consume an excessive amount of water in a short period, exceeding your kidney’s ability to eliminate water, per StatPearls. Flooding your system with water beyond what your kidneys can excrete dilutes the electrolytes in your blood, particularly sodium. This imbalance disrupts the normal functioning of cells, leading to swelling and potential complications.

“Hyponatremia can cause your blood sodium level to drop too low,” cautions Semiya Aziz, BSc (Hons), MBBS, MRCGP, DFSRH, BSLM/IBLM, a general practitioner in North London, UK, and founder of Say GP. “Sodium is an important electrolyte that helps regulate the water balance and the function of the nerves and muscles in the body. Water intoxication is rare and usually happens when someone drinks more than one liter of water per hour for several hours without replacing lost electrolytes.”

Symptoms and Signs

According to MedlinePlus, drinking too much water or water intoxication, can lead to various symptoms as a result of electrolyte imbalance. Initial signs may include drowsiness, muscle weakness or cramping, increased blood pressure and double vision, but symptoms may become more severe as the condition progresses. Here’s a breakdown of potential symptoms:

• Fatigue
• Confusion
• Headaches
• Drowsiness
• Double vision
• Decreased urination
• Nausea and vomiting
• Increased blood pressure
• Muscle weakness or cramping
• Inability to identify sensory stimuli

Effects of Drinking Too Much Water

Trista Best, RD, a registered dietitian with Balance One Supplements, tells EatingWell, “Excess water consumption causes a dilution of sodium levels in the blood, leading to symptoms such as nausea, headache, confusion, seizures, and in extreme cases, coma or death. The swelling of cells, especially in the brain, due to low sodium concentration can result in increased intracranial pressure, which may manifest as symptoms ranging from mild discomfort to severe neurological issues.”

Dilution of Sodium Levels

Sodium is crucial in maintaining proper fluid balance within and around your cells. A 2016 review in the Journal of Clinical Neurology noted that diluting sodium levels in the blood can lead to symptoms ranging from mild nausea to seizures and can be life-threatening in severe cases.

Swelling of Cells

While cells can typically regulate their water content, overwhelming them with too much water can disrupt this balance. Cellular swelling may result in various issues, including impaired cellular function and increased pressure within tissues, which research, such as a 2019 review in Nutrients, points out can be fatal if it causes brain swelling beyond 5-8% of your skull’s capacity.

Impaired Kidney Function

Your kidneys play a crucial role in maintaining your body’s fluid balance. However, water intoxication can strain these vital organs. Drinking too much water in a short period can overwhelm your kidneys’ ability to excrete excess water and impact their ability to function properly, states the British Nutrition Foundation.

Risks and Complications

Although water intoxication is uncommon, it can pose serious health risks and complications. Besides the adverse effects described above, Best says, “Excessive water consumption can overload the circulatory system, leading to edema (fluid retention) and putting additional stress on the heart, potentially causing cardiovascular issues. Additionally, overhydration can disrupt the balance of other essential electrolytes besides sodium, such as potassium, magnesium and chloride, impacting various bodily functions.”

Treatment and Prevention

While the type of treatment may vary depending on risks and complications, there are some practical measures you can take to help prevent and treat water intoxication:

• Monitor water intake: Avoid drinking more than 0.8 to 1 liter of water per hour, and drink according to your thirst and physical activity level.
• Balance electrolytes: Carefully consume electrolyte-rich fluids or foods, especially if you sweat a lot or exercise for a long time. This practice can help prevent the dilution of sodium in your blood. Check with your health care provider if electrolyte drinks are a good option for you.  
• Seek medical attention if symptoms occur: If you experience any signs of water intoxication, such as nausea, headache, confusion, or seizures, seek immediate medical help. You may need intravenous fluids containing sodium, various medications, or other treatments to restore your sodium level and reduce the swelling of your cells. 

“Water intoxication is a rare but serious condition that can be fatal if not treated promptly,” says Aziz. “Therefore, it’s important to be aware of the risks and prevention tips and to act quickly if you suspect you or someone else has water intoxication.”

How Much Water Do You Need Every Day?

Like anything nutrition-related, there’s no one-size-fits-all approach to water consumption. According to the Institute of Medicine of the National Academies, the recommendation is 3.7 liters per day for men ages 19 to 30 and 2.7 liters per day for women in the same age range. However, individual requirements vary based on age, weight, diet, activity level and climate, so adjusting this based on individual needs is essential. If you’re physically active, live in a hot climate or are pregnant, you may need more water than the average person. Just be mindful of the risks of overhydration.

Frequently Asked Questions

How much water is needed for intoxication?

Water intoxication occurs when you drink an excessive amount of water, generally beyond what your kidneys can excrete. The exact quantity varies among individuals, but it’s often linked to consuming multiple liters of water in a short span without consuming electrolytes, leading to electrolyte imbalance.

How much water causes overhydration?

Overhydration, or water toxicity, can result from consuming an amount of water that surpasses your kidneys’ ability to eliminate it. This condition can occur when you excessively and rapidly drink more water than your body can safely process.

Is 4 liters of water a day too much?

The general guideline is around eight (8-ounce) glasses per day. That said, the amount of water is as important as the period of time in which one drinks it. Additionally, individual needs differ, so be sure to check with your health care provider the right amount of water for you based on factors like climate, diet, and physical activity to make sure you’re staying hydrated.

Can water intoxication be fatal?

In extreme cases, water intoxication can lead to hyponatremia. In this condition, low sodium levels in the blood can cause swelling of the brain, leading to seizures, coma, and potentially death.

The Bottom Line

While drinking water is undeniably essential for good overall health and supporting optimal bodily functions, it’s vital to strike a healthy balance in your water intake to prevent the potential risks of overhydration. Symptoms of water intoxication range from fatigue to confusion, swelling of cells and impaired kidney function. The recommended amount of daily water intake varies based on individual factors but should still be considered when staying hydrated. To help prevent the health risks associated with drinking too much water, practice moderation, maintain electrolyte balance, and seek medical attention when needed.