HT Health Talk: With north India’s plains sweltering under a relentless June heatwave and temperatures consistently breaching 40°C, the line between summer discomfort and a medical emergency has thinned. The gap between morning and evening cooling is shrinking, leaving people vulnerable to severe heat illnesses. Also read | HT Health Talk: You asked, our experts answered how to manage migraine in summer
Many people use ‘heat exhaustion’ and ‘heatstroke‘ interchangeably, but medically, they are entirely different beasts. Understanding the threshold where one crosses into the other can save a life. Moreover, if you suspect someone near you has suffered heatstroke, your immediate actions before emergency medical services arrive are vital.
In this week’s HT Health Talk, we bring you exclusive insights from Dr Santosh Pandey, consultant, emergency medicine and trauma Care at Medanta, Noida. Ahead, Dr Pandey answers pressing questions from Hindustan Times readers, busting common summer myths and providing a medical roadmap to surviving extreme heat stress. Also read | 24-year-old Bengal student dies of heatstroke, marking first heat-related death at Delhi’s RML
1. We often hear ‘heat exhaustion’ and ‘heatstroke’ used interchangeably, but medically, they are quite different. What are the key differentiating signs that tell a family member or bystander that someone has progressed from exhaustion to a life-threatening sunstroke?
Heat exhaustion and heatstroke exist on the same spectrum, but heatstroke is a medical emergency. A person with heat exhaustion may experience heavy sweating, weakness, dizziness, headache, nausea, muscle cramps, and a rapid pulse while remaining alert and responsive. Heatstroke occurs when the body’s core temperature rises dangerously, typically above 40°C, and the brain begins to malfunction. Warning signs include confusion, disorientation, slurred speech, seizures, loss of consciousness, or unusual behavior. If a person becomes mentally altered or unresponsive after heat exposure, it should be treated as heatstroke and emergency medical help should be sought immediately.
2. It is a common belief that a heatstroke victim will always be sweating heavily. Is it true that a lack of sweat (dry, hot skin) is actually a sign of advanced heatstroke, and why does the body stop sweating?
A common misconception is that all heatstroke patients stop sweating. In reality, some individuals, particularly those with exertional heatstroke, may continue to sweat. However, hot, dry skin can be a sign of advanced heatstroke. Normally, sweating helps cool the body through evaporation. During severe heat stress, the body’s cooling mechanisms can become overwhelmed, leading to dehydration and failure of sweat production in some cases. As a result, body temperature rises rapidly, increasing the risk of organ damage. The absence of sweating should never be used alone to diagnose heatstroke; changes in mental status remain the most critical warning sign.
3. If someone is suspected of having a sunstroke, what are the immediate ‘dos’ and ‘don’ts’ while waiting for an ambulance? Should we submerge them in ice, or can that cause a shock to their system?
If heatstroke is suspected, call emergency medical services immediately and move the person to a cool, shaded, or air-conditioned area. Remove excess clothing and begin active cooling using cool water, wet towels, fans, or ice packs placed on the neck, armpits, and groin. If the person is conscious and able to swallow, small sips of cool fluids may be offered. Do not force fluids if they are confused or unconscious. Full-body cold-water immersion is highly effective for severe heatstroke when done appropriately, but unsupervised ice immersion may not be practical in all settings. The priority is rapid cooling while awaiting professional medical care.
4. Many fitness enthusiasts track the temperature, but how does high humidity alter how our body cools itself down during an outdoor run or workout? At what temperature/humidity combination should someone strictly move their workout indoors?
Humidity significantly affects the body’s ability to cool itself. Sweat cools the body only when it evaporates from the skin. In high humidity, sweat does not evaporate efficiently, causing heat to build up even when temperatures are not extremely high. This increases the risk of heat exhaustion and heatstroke during outdoor workouts. Individuals should pay attention to the heat index, which combines temperature and humidity. When temperatures exceed approximately 32–35°C with high humidity, strenuous outdoor exercise should be reduced or shifted indoors. The exact threshold may vary depending on age, fitness level, acclimatisation, and underlying health conditions.
5. With temperatures crossing 40°C across the plains this June, the morning and evening gaps are narrowing. What is the safest window for outdoor exercise, and how should a person modify the intensity of their workout during a heatwave?
During a heatwave, the safest time for outdoor exercise is generally around sunrise, when temperatures and solar radiation are at their lowest. Evening workouts may still be risky because roads, buildings, and concrete surfaces continue to radiate stored heat after sunset. Exercise intensity should be reduced during periods of extreme heat, with longer rest intervals and increased hydration. Activities that normally feel manageable can become significantly more demanding during a heatwave. Individuals should listen to their bodies and stop exercising if they experience dizziness, excessive fatigue, headache, nausea, or unusual shortness of breath.
6. Are there certain demographic groups — like teenagers or older adults who love their daily outdoor walks — whose bodies regulate heat differently, making them hit heat exhaustion much faster than others?
Certain groups are more vulnerable because their bodies regulate heat less efficiently. Older adults often have a reduced ability to sweat, diminished thirst perception, and may take medications that affect hydration or temperature regulation. Children and teenagers can also be at higher risk during intense physical activity because they generate significant metabolic heat. Individuals with obesity, cardiovascular disease, diabetes, kidney disorders, or those taking certain medications are particularly susceptible. Outdoor workers and athletes are also at risk because of prolonged exposure and exertion. Understanding personal risk factors is important for preventing heat-related illnesses during extreme weather conditions.
7. People are told to ‘drink plenty of water’ during a heatwave. However, can drinking too much plain water without replacing electrolytes cause a dangerous drop in blood sodium levels? How do we strike the right balance?
While staying hydrated is essential, excessive consumption of plain water without adequate electrolyte replacement can sometimes lead to hyponatremia, a condition where blood sodium levels become dangerously low. Symptoms may include headache, nausea, confusion, muscle cramps, and in severe cases, seizures. This is more common during prolonged physical activity accompanied by heavy sweating. The goal is balanced hydration rather than simply drinking large quantities of water. Most people can maintain this balance through a combination of water, electrolyte-containing beverages, and regular meals. Those engaging in prolonged exercise during extreme heat may benefit from drinks that replace both fluids and electrolytes.
8. Is there any medical truth to the warning that drinking ice-cold water immediately after coming inside from the scorching sun can cause a ‘shock’ to the body or blood vessels, or is it perfectly safe?
There is little scientific evidence that drinking ice-cold water after coming indoors from a hot environment causes a dangerous ‘shock’ to the body. For most healthy individuals, cold water is safe and may even help reduce body temperature and improve comfort. Some people may experience temporary discomfort, stomach cramps, or sensitivity if they drink very cold fluids rapidly, but this is generally not harmful. The key is gradual rehydration rather than consuming large amounts at once. Individuals with specific medical conditions affecting swallowing or digestion may require personalised advice from their healthcare provider.
9. How do traditional Indian summer drinks like aam panna, buttermilk/chaas, and nimbu paani compare to modern commercial sports drinks or standard ORS (Oral Rehydration Salts) when it comes to combating extreme heatwave conditions?
Traditional Indian beverages such as aam panna, chaas, and nimbu paani can be excellent options for maintaining hydration, particularly when prepared hygienically and with appropriate amounts of salt and sugar. These drinks provide fluids and varying levels of electrolytes, while also being culturally familiar and affordable. Commercial sports drinks may be useful during prolonged or intense exercise because they contain measured amounts of carbohydrates and electrolytes. Standard ORS remains the preferred option when dehydration is significant due to excessive sweating, illness, or heat-related conditions. The best choice depends on the level of physical activity, duration of exposure, and degree of fluid loss.
10. Why do so many people experience severe loss of appetite, bloating, or sluggish digestion during a heatwave? How does the body shifting its blood flow away from the gut to the skin to cool down affect our digestive health?
Many people notice reduced appetite, bloating, or digestive discomfort during periods of extreme heat. One reason is that the body prioritises cooling itself by increasing blood flow to the skin. This can reduce blood supply to the digestive tract, slowing digestion and contributing to feelings of heaviness or loss of appetite. Heat can also affect hydration levels and alter normal gastrointestinal function. As a result, lighter meals, fruits, vegetables, and adequate fluid intake are often better tolerated during hot weather. Eating large, heavy, or excessively fatty meals may increase discomfort and place additional strain on the body.
11. Many budget or local fitness centres in India operate without air conditioning, relying entirely on exhaust fans and wall fans while packed with crowded evening batches. From a sports medicine perspective, what are the hidden health risks of working out in an enclosed, highly humid environment where scores of people are radiating body heat simultaneously? At what point does ‘pushing your limits’ in such an atmosphere become a straight road to heat exhaustion or rhabdomyolysis (severe muscle breakdown)?
Crowded gyms without adequate ventilation can become high-risk environments during hot weather. As multiple individuals exercise simultaneously, body heat and moisture accumulate, raising both temperature and humidity levels. Fans may improve comfort but do not effectively lower ambient heat or humidity. Under such conditions, sweat evaporates less efficiently, increasing the risk of dehydration, heat exhaustion, heatstroke, and reduced exercise performance. In severe cases, prolonged intense exertion in a hot, humid environment can contribute to exertional rhabdomyolysis, a serious condition involving muscle breakdown that may damage the kidneys. Symptoms such as dizziness, confusion, severe cramps, excessive fatigue, or dark urine should never be ignored.
