Heatwaves were once thought of as a seasonal phenomenon that people could handle with a fan, water, and shade. That is no longer true. Temperatures during these heatwaves are reaching 40°C to 46°C. In April, AOI.in found that the world’s 50 hottest cities were all in India, with none from the Middle East making the list.

According to scientists, this kind of tremendous heat is occurring more frequently. A serious warning of the dangers of extended heat is provided by history. Millions of people worldwide, roughly 4 per cent of the world's population, died due to droughts, heatwaves, and the ensuing famines during the intense El Niño event of 1877–1878.

As the temperature rises in India, the warm nights provide no respite. The medical profession states that heat has become a long-term health hazard, affecting much more than just comfort. Be it increased stress on the heart and kidneys or problems related to infertility and hormonal imbalance, the effect of heat has manifested in many bodily systems.

“People often underestimate how dangerous prolonged heat exposure can be,” said Dr Vikramjeet Singh, Senior Consultant in Internal Medicine at Aakash Healthcare. “It can lead to heat exhaustion, heatstroke, and worsen pre-existing conditions such as cardiac and respiratory illnesses.”

One of the biggest changes doctors are noticing is that heat is no longer limited to the daytime. Nights, once considered recovery periods, are staying hotter for longer.

“When nights remain warm, the body does not get enough time to recover,” said Dr Charu Dutt Arora, Consultant Physician and Head of Palliative Care and Geriatrics at Asian Hospital’s AmeriHealth Home Health Care. “That leads to fatigue, poor sleep, weak immunity and a higher risk of illness.”

The result is a form of continuous physiological stress, with the body struggling to cool down around the clock.

Children and Elderly Face the Highest Risk

As per The Healthy Indian Project (THIP), children and older adults are more vulnerable to extreme heat because their bodies are less efficient at regulating temperature, making them more prone to dehydration, heat exhaustion and heatstroke.

“Young children and the elderly have weaker body temperature control,” said Dr Sameer Punia, Senior Consultant and Paediatrics Intensivist. “Children may not recognise dehydration, while older adults often have reduced cooling ability and underlying illnesses.”
Dr Saarthak Bakshi, Healthcare Entrepreneur and CEO of RISAA IVF, said older people may not sweat enough or feel thirsty in time, while children depend heavily on adults to ensure hydration and protection.
Hospitals are already seeing common heat-related complications in these groups, including dehydration, dizziness, fainting and heatstroke. In older adults, doctors are also reporting confusion, electrolyte imbalance and kidney complications.
Existing Illnesses Make Heat Far More Dangerous
For people living with chronic disease, heatwaves can quickly become life-threatening.
“High temperatures force the body to work harder to cool itself,” Dr Punia said. “That increases strain on the heart and can trigger serious events like heart attacks or strokes.”
Respiratory illnesses can also worsen, especially when high heat combines with poor air quality. Dehydration, meanwhile, reduces blood flow to the kidneys and raises the risk of stones, infections and kidney damage. Despite those risks, doctors say awareness remains low.
“A lot of patients are unaware of how heat affects their disease or medication,” Dr Punia said. “The information is often too generic.”
The Health Impact Goes Beyond Heatstroke
Medical professionals believe that this year’s heat is causing health issues beyond what is normally considered. Hormonal and reproductive problems have begun to surface in women as a result of heat exposure.
“Exposure to heat can cause imbalances in hormones, thereby causing irregular cycles, and making conditions such as PCOS worse,” explained Dr. Archana Dhawan Bajaj, Gynaecologist and IVF Expert at Nurture IVF Clinic.
According to Dr. Hrishikesh Pai, a Consultant Gynaecologist and IVF Specialist from Lilavati and Fortis Hospitals, increased temperatures also make it harder for women to conceive in certain cases.
Reproductive health for males is also under threat.
"Excessive heat can cause poor quality of sperm and result in male infertility," said Dr. Vineet Malhotra, Head of Urology and Director at VNA Hospital. Even dermatologists have seen an increase in skin disorders related to sweating and exposure to the sun.
"The hot summers along with excessive heat and sweat can cause heat rash, fungal infections, acne problems, and skin pigmentation," said Dr. Gagana B. Gopal, Dermatologist at Kaya Limited.
A New Public Health Reality
Doctors say the larger lesson is that heatwaves can no longer be treated as isolated weather events. “Hotter days are no longer just about weather. They are a health risk affecting several body systems,” Dr Vikramjeet Singh said.
While experts are advising individuals to stay away from peak temperatures in the afternoon, keep themselves well-hydrated, wear light clothes and seek immediate medical attention if any symptoms develop, they believe such measures alone would not suffice.
In view of the increasing duration, frequency and intensity of the heat waves being experienced around the world, especially in India, doctors are of the opinion that dealing with extreme temperatures is no longer a seasonal issue.