Heat stress symptoms: Watch out for fatigue, dehydration, heat stroke, more

Symptoms of heat stress: Early symptoms of heat stress include excessive sweating, fatigue, dizziness, increased thirst, muscle cramps, and a rapid heartbeat (Image: Canva)

Come summers and the struggle with rising temperatures begins, causing severe heatwaves. During the hotter months heatwaves become more frequent, which increases the risk of heat stress. It is during these months that the body struggles to cool itself in extreme heat, leading to exhaustion, dehydration, and in some cases serious conditions like heat stroke.

Heat stress happens when the body is unable to regulate its temperature due to prolonged exposure to high temperatures, inadequate hydration, or poor ventilation, says Dr Madhav R. Dharme, Consultant - General Medicine & Critical Care at Sahyadri Super Speciality Hospital, Hadapsar, Pune. “While sweating is the body’s natural way to cool down, excessive heat can lead to dehydration, fatigue, and, heat stroke,” he says.

Studies suggest that when exposed to high temperatures, the body reacts by increasing sweat production and redirecting blood flow toward the skin to release excess heat. “However, in extreme conditions, this cooling process may not be sufficient. In prolonged heat exposure, the heart works harder to pump blood, increasing both heart rate and blood pressure. This puts extra strain on the cardiovascular system, particularly in those with existing heart conditions,” says Dr Dharme.

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He adds, “If the body fails to cool down, it can lead to heat-related illnesses such as heat cramps, heat exhaustion, and heat stroke. In severe cases, excessive strain on the heart may result in fainting or even cardiac arrest. The risk is particularly high for older adults, outdoor workers, and athletes engaged in intense physical activity.”

Symptoms of heat stress:

Symptoms of heat stress may range from mild discomfort to life-threatening conditions. “The early signs include, excessive sweating, fatigue, dizziness, increased thirst, muscle cramps, and a rapid heartbeat,” says Dr Dharme. He says that as the condition worsens, the body may struggle to cool itself, leading to more severe signs. “The severe symptoms include, hot, dry skin, a dangerously high body temperature (above 103°F or 39.4°C), confusion, rapid breathing, fainting, or even seizures. Heat stroke is a medical emergency that requires immediate attention. If left untreated, it can cause permanent organ damage,” warns Dr Dharme.

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Risk factors:

While heat stress can affect anyone, certain groups are more vulnerable. “These include people working in poorly ventilated indoor environments without air conditioning, who are at high risk. Similarly, those unaccustomed to high temperatures, such as travellers from cooler climates or those with low physical fitness, may develop heat stress more quickly,” he says.

According to multiple studies, environmental factors also play a crucial role. Agrees Dr Dharme, “With rising global temperatures and more frequent heatwaves, even regions previously unaffected by extreme heat are now at risk. Climate change has intensified heat-related health risks, making it more important than ever to take preventive measures.”

He suggests a few simple and effective measures to prevent and manage heat stress:

• Stay hydrated: Drink plenty of water throughout the day. Avoid alcohol and caffeine, as they contribute to dehydration.

• Adjust activity levels: Schedule demanding physical tasks during cooler hours in the morning or evening.

• Wear light clothing: Loose, breathable fabrics help sweat evaporate more efficiently, keeping the body cool.

• Use cooling systems: Fans, air conditioning, and staying in shaded areas can significantly lower body temperature.

• Monitor early symptoms : Pay attention to early symptoms and take immediate action to cool down before heat stress escalates.