Summer health advice usually sounds predictable: stay hydrated, avoid the sun, don’t skip sunscreen. But there’s another stress your body is dealing with that barely gets talked about, constantly switching
between scorching outdoor heat and freezing indoor AC.
It feels harmless, even comforting in the moment. But that back-and-forth? It’s quietly putting your body under more strain than you might think.
Dr Suman Mitra, Internal Medicine Specialist, CK Birla Hospitals, CMRI, says this constant temperature whiplash is one of the most overlooked health risks of the season, especially in cities like Kolkata, where heat and humidity are already pushing the body to its limits.
The physiology is straightforward. When the body moves abruptly from intense heat into a cold indoor environment, blood vessels constrict rapidly, blood pressure fluctuates, and the cardiovascular system has to recalibrate within a very short window. For most healthy adults, this produces nothing more than momentary dizziness or fatigue.
For people already managing chronic conditions such as diabetes, heart disease, or hypertension, that same transition can tip the balance toward something more serious. Blood pressure that is already unstable does not respond well to repeated vascular stress. Medications like diuretics, which are commonly prescribed in these populations, accelerate fluid loss and further reduce the body’s tolerance for thermal disruption.
Dehydration adds another layer that most people do not account for. Fluid loss does not stop indoors. Air conditioning removes humidity from the environment, drawing moisture from the body in ways that are less perceptible than sweating in direct heat. People moving between these two environments tend to underestimate how much fluid they are losing over the course of a day, and by the time obvious symptoms appear, the deficit is already significant.
Dr Mitra flags a particular concern around how repeated AC transitions can obscure the early warning signs of heat exhaustion. Symptoms like mild fatigue, a slight headache, or reduced concentration are often attributed to air conditioning rather than to heat stress. By the time the picture becomes clearer, when you see altered sensorium, severe fatigue, or, in extreme cases, seizures, the situation has often progressed beyond what rest and hydration can easily address and requires medical attention.
The practical advice is not complicated. Keep the temperature gap between indoor and outdoor environments as narrow as is comfortable. Give the body a few minutes to adjust when moving between the two, rather than stepping directly from peak outdoor heat into a heavily cooled room. Drink water consistently throughout the day, regardless of whether you feel thirsty. These are not dramatic interventions, but during a sustained heatwave, they can make a measurable difference.
