Heatwave Alert Issued In Many Indian States: Doctor Explains Safety Tips, Do's And Don'ts

India is once again grappling with intense heatwave conditions, with temperatures crossing 40 degrees Celsius in several states as early as April. The India Meteorological Department (IMD) has issued multiple alerts, warning of prolonged heat exposure risks and urging precaution, particularly for vulnerable groups. While heat may seem like a seasonal inconvenience, medical experts stress that extreme temperatures can have serious, even life-threatening consequences. Heatwaves place enormous strain on the human body, affecting the cardiovascular system, kidneys, brain, and metabolism.

"Extreme heat is not just discomfort. It's a multi-organ stressor affecting the heart, brain, kidneys, and metabolism," explains Dr Sanjay Verma, Senior Consultant, Internal Medicine, Fortis Escorts, Okhla, Delhi. What makes early-season heat particularly dangerous is the body's lack of acclimatisation. Combined with urban heat island effects, dehydration, and chronic illnesses, heatwaves can significantly increase the risk of heat exhaustion, heatstroke, and long-term health complications.

Understanding how heat affects the body, and how to respond, can be lifesaving.

Why Early Heatwaves Are More Dangerous

"Early-season heatwaves are more dangerous because the body hasn't acclimatised yet," says Dr Verma. In April, the body is still in a "winter-adjusted" state:

• Sweating starts later
• Salt loss is higher
• Blood circulation is less efficient

"By May-June, the body adapts by sweating earlier and more efficiently and maintaining better circulation," he explains. This means a 45 degrees Celsius day in April can put sudden stress on the cardiovascular system, increasing risks of dehydration, fainting, and heatstroke. Rapid temperature spikes are associated with increased mortality during heatwaves.

Why Your Body Works Harder In Extreme Heat

At temperatures above 40 degrees Celsius, the body expends more energy simply to stay cool. "Skin vasodilation forces the heart to pump harder, sweating requires energy, and the brain constantly regulates temperature," says Dr Verma.

Key physiological responses include:

• Increased heart workload (similar to mild continuous exercise)
• Kidney strain to conserve water
• Activation of heat-shock proteins to protect cells

This explains why people often feel fatigued even without physical activity. Prolonged heat exposure can significantly alter metabolic and cardiovascular function.

Also Read: Is There A Wrong Way To Hydrate? Doctors Explain Hydration Mistakes You Are Making During A Heatwave

Urban Heat Island Effect: A Hidden Risk

Cities like Delhi often experience temperatures 3-7 degrees Celsius higher than surrounding areas due to the Urban Heat Island (UHI) effect. "Concrete traps heat, lack of trees reduces cooling, and vehicles and AC units add to heat load," Dr Verma explains.

Nighttime heat is especially harmful:

• The body cannot cool down
• No physiological recovery occurs
• Heat stress accumulates over days

"Lack of nighttime cooling significantly worsens health outcomes," he adds.

Why Heat Causes Digestive Issues

Heatwaves often trigger digestive discomfort, and there's a clear scientific reason. "Blood is diverted to the skin for cooling, reducing blood flow to the gut, and this slows digestion," says Dr Verma.

Combined with dehydration and electrolyte imbalance, this can lead to:

• Bloating and acidity
• Appetite loss
• Abdominal cramps

Heat And Mental Health: Not Just Irritability

"Heat irritability has a strong neurological basis," Dr Verma notes.

High temperatures:

• Disrupt neurotransmitters like serotonin and dopamine
• Reduce brain perfusion due to dehydration
• Increase cortisol (stress hormone)

This can result in:

• Irritability and aggression
• Anxiety
• Poor sleep

Who Is Most At Risk?

Certain groups are more vulnerable to heat-related illness:

1. People With Diabetes: "Impaired sweating and higher dehydration risk make temperature regulation difficult," says Dr Verma.
2. Chronic Kidney Disease (CKD) Patients: "Heat can worsen dehydration and increase risk of acute kidney injury," he explains.
3. Outdoor Workers: Repeated exposure can lead to heat stress nephropathy, a growing concern in India.

The Indian Council of Medical Research (ICMR) has flagged rising kidney disease risks among heat-exposed workers.

Also Read: Can Wearables Protect You From Heatwaves? Doctors And Experts Explain

Why Fans May Not Work In Extreme Heat

Many rely on fans for relief, but they may fail at very high temperatures. "If air temperature exceeds body temperature, fans can blow hot air and worsen dehydration," warns Dr Verma.

• In dry heat, it leads to rapid sweat evaporation causing dehydration
• In humid heat, sweat doesn't evaporate, reducing cooling

At extreme temperatures, cooling methods like air conditioning, hydration, and shade are essential.

Heatstroke First Aid: What To Do Immediately

Heatstroke is a medical emergency that can cause brain damage within minutes. "If someone is confused or stops sweating, act immediately," Dr Verma advises.

Steps to follow:

1. Rapid cooling: move to shade, apply water, fan aggressively
2. Position: lay flat, elevate legs; recovery position if unconscious
3. Hydration: give water or ORS only if conscious
4. Avoid forcing fluids in an unconscious person.

Heatwaves are becoming more frequent and intense, posing serious health risks across India. Beyond discomfort, extreme heat affects multiple organs and can trigger life-threatening conditions like heatstroke and kidney failure. As Dr Verma underscores, "Extreme heat is a systemic stressor that requires proactive management, not passive endurance." From staying hydrated and avoiding peak sun hours to recognising early warning signs, simple measures can make a critical difference. With climate change intensifying heat extremes, awareness and preparedness are no longer optional, they are essential for survival.

Disclaimer: This content, including advice, provides generic information only. It is in no way a substitute for a qualified medical opinion. Always consult a specialist or your own doctor for more information. NDTV does not claim responsibility for this information.