Then 34-year-old software team lead Ramesh Varma collapsed along the Chittur road in Kochi on a sweltering Thursday evening, emergency responders initially suspected heatstroke. Not too far away, Palakkad was boiling under 40°C heat, and ambient humidity hung heavy in the air. At the hospital, however, blood tests revealed a paradoxical diagnosis: Ramesh was suffering from acute dilutional hyponatremia, commonly known as water intoxication.
Driven by extreme weather advisories and ubiquitous online wellness trends urging massive fluid intake during summer, Ramesh had been forcing himself to drink over six litres of plain water every day. In doing so, he had flushed his bloodstream of essential sodium, causing rapid cellular swelling that triggered severe headaches, muscle cramps, and sudden disorientation. His case is a classic example of overcorrection. In tropical climates, people often assume that if water is good, more water must be infinitely better. But excessive consumption of pure water without electrolyte replenishment can be just as dangerous as acute dehydration.
Ramesh’s hospitalisation highlights a growing clinical concern across the region: as summer temperatures rise and humidity spikes, basic public health messaging around hydration is frequently misunderstood.
The human body relies on a delicate balance between water and key electrolytes, primarily sodium, potassium, and chloride. When the sweat rate increases, the body loses both water and essential minerals. Drinking vast quantities of plain, unmineralised water in a short period dilutes extracellular fluid. The kidneys, capable of excreting roughly 800 to 1,000 millilitres of fluid per hour under normal conditions, become overwhelmed, shifting excess water into tissues.
“From a medical point of view, too little water consumption as well as too much water consumption may result in negative consequences,” notes Dr Brunda M S, senior consultant in internal medicine at Aster CMI Hospital, Bengaluru. “Insufficient consumption of water may provoke dehydration, headaches, dizziness, constipation, low blood pressure, formation of kidney stones, and even kidney damage in severe cases. In turn, excessive consumption of water, especially at once, results in lowering the amount of sodium in the blood, leading to hyponatremia.”
This dual concern was also echoed by Dr Vinod Xavier, consultant in internal medicine at Aster Medcity, Kochi. “Inadequate water intake leads to chronic dehydration, UTIs, constipation, and reduced kidney functions. On the other hand, overhydration, while less frequent, drops blood sodium to dangerous levels,” he explains.
Hydration is fundamentally about chemical equilibrium rather than volumetric throughput. When an individual sweats heavily, pouring pure water into a depleted system without sodium creates a severe osmotic imbalance. Traditional regional remedies like spiced buttermilk with a pinch of salt or fresh tender coconut water are naturally isotonic, restoring serum sodium alongside fluid volume far better than distilled or reverse-osmosis purified water alone.
Clinicians point out that public perception of fluid requirements remains deeply rooted in outdated guidelines and fitness trends that lack medical backing. Chief among these is the “8x8 rule,” which advises drinking eight 8-ounce glasses of water daily.
“The widely quoted 8x8 rule is a nice little guideline, but it really isn’t backed by strong science and shouldn’t be treated like a universal must-do,” says Aditi Prasad Apte, senior clinical nutritionist at Aster RV Hospital, Bengaluru. “Hydration requirements change depending on age, body size, activity level, climate, diet, and general health status. Also, it’s not true that plain water has to be the only source. Milk, soups, herbal teas, and water-rich foods like fruits and vegetables all help toward daily fluid intake in a very real way.”
Dr Xavier agrees that blanket metrics ignore basic individual biology, stressing that the rule ignores individual variation such as differences in climate, physical activity, and metabolic rate, while overlooking how solid foods contribute toward daily hydration.
The rule serves as a general guide rather than a medical necessity, says Dr Brunda, adding that the body naturally alerts us when more fluids are required through thirst, and for most healthy individuals, drinking when thirsty and having slightly yellow-coloured urine works fine.
When sodium concentration in the blood drops below normal limits — typically 135 milliequivalents per litre — the osmotic shift forces water out of the vascular space and directly into surrounding tissue cells. In most parts of the body, minor tissue swelling causes localised edema. However, within the rigid container of the human skull, cerebral edema rapidly becomes life-threatening.
As brain cells absorb excess fluid and expand, intracranial pressure rises. The early warning signs —dizziness, lethargy, lightheadedness, and mild nausea — are routinely mistaken for dehydration itself. Patients often react by drinking even more plain water, accelerating the neurological decline toward confusion, seizures, or loss of consciousness.
Apte warns that chugging too much water in a short span can dilute sodium in the bloodstream, bringing about hyponatremia with symptoms like nausea, confusion, muscle cramps, seizures, and in unusual situations, coma. She notes that individuals with heart, kidney, or liver disease require medical oversight and a tighter routine. Dr Brunda concurs, emphasising that people with heart, liver, or kidney conditions are especially sensitive to excess fluid, proving that drinking more water is not always better.
Ultimately, navigating tropical summers safely requires shifting away from rigid volumetric rules and trusting the body’s calibrated physiological signals. By replacing forced water quotas with mindful attention to natural thirst, monitoring urine colour, and utilising electrolyte-rich traditional drinks during heavy exertion, individuals can maintain proper fluid balance without risking the hidden dangers of overhydration.
Relook at traditional practices
Long before commercial sports drinks flooded the market, regional food cultures in tropical zones developed effective, low-cost hydration practices tailored to high heat and humidity. Traditional beverages were explicitly formulated around mineral balance rather than plain water volume. Spiced buttermilk combines water with dairy proteins, lactic acid, trace minerals, minced ginger, green chilies, curry leaves, and a generous pinch of sea salt. The salt supplies sodium to maintain osmotic pressure, while trace fat and protein slow gastric emptying, allowing for sustained fluid absorption over several hours. Similarly, cumin-infused jeera water, and fresh tender coconut water offer complex mineral profiles. Tender coconut water naturally provides potassium, magnesium, and sodium in proportions close to human blood plasma, making it an ideal rehydration solution for mild heat stress.
Clinical & practical boundaries
Individual variability: Age, lean body mass, local humidity, and metabolic rate dictate fluid needs, making one-size-fits-all targets inaccurate
Renal filtration limits: Healthy kidneys can excrete less than a litre of fluid per hour, making sudden excessive consumption dangerous
Pre-hydration myth: Drinking massive amounts of water before stepping out into extreme heat speeds up excretion rather than storing usable fluid
Electrolytes & fluid sources
The electrolyte rule: Heavy sweating strips the body of both water and sodium — replenishing with plain, mineral-free water alone dilutes blood chemistry
Dietary hydration: Up to 30% of daily fluid intake comes naturally from solid foods like fruits, vegetables, and traditional broths
Traditional solutions: Spiced buttermilk with salt, and fresh tender coconut water offer naturally balanced isotonic rehydration
