Beyond Dehydration: How Heatwaves Can Affect Your Heart, Lungs, Brain And More

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Heatwaves are among the deadliest natural hazards, yet they often receive less attention than floods, cyclones, or wildfires because their impacts are less visible. According to the World Health Organization (WHO), approximately 4,89,000 heat-related deaths occurred annually worldwide between 2000 and 2019. As climate change drives rising temperatures, heatwaves are becoming more frequent, prolonged, and intense, increasing the risk of illness and death.

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Extreme heat can affect multiple systems of the body, including the brain, heart, lungs, muscles, skin, and circulatory system. Understanding these health risks and recognising early warning signs is essential to preventing serious heat-related illness and reducing mortality.

Effects of Dehydration & Electrolyte Imbalance

Nausea

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It is often one of the earliest signs of heat-related illness. Excessive sweating during a heatwave causes the body to lose water and essential electrolytes, disrupting normal bodily functions. This can lead to sickness, loss of appetite, dizziness, and sometimes vomiting. While it may seem minor, nausea can indicate that the body is under significant heat stress and may be progressing towards heat exhaustion.​

Low Blood Pressure

At the same time, dehydration can contribute to low blood pressure. During hot weather, blood vessels widen to help release excess heat from the body. Combined with reduced blood pressure and reduced blood flow to the brain. As a result, individuals may experience lightheadedness, weakness, blurred vision, or even fainting.​

Heat Cramps

According to the Center for Disease Control and Prevention (CDC) electrolyte depletion can lead to heat cramps, which are painful muscle spasms that commonly occur in the legs, arms, abdomen, or back. These cramps often develop after intense sweating and physical activity in hot conditions, serving as another indication that the body's fluid and mineral reserves need replenishment.

​Cardiovascular & Respiratory Effects of Heatwave

Worsening of Heart Disease

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Extreme heat places additional strain on the cardiovascular system as the heart works harder to circulate blood and regulate body temperature. This increased workload can worsen existing heart conditions and raise the risk of complications, particularly among older adults and individuals with cardiovascular disease. Symptoms may include chest discomfort, shortness of breath, palpitations, and unusual fatigue.

Respiratory Issue

Heatwaves can also affect respiratory health, especially when accompanied by poor air quality. High temperatures can increase the formation of pollutants such as ground-level ozone, which irritate the airways and make breathing more difficult. People with asthma, Chronic Obstructive Pulmonary Disease (COPD), and other respiratory conditions may experience worsening symptoms, including coughing, wheezing, chest tightness, and shortness of breath.

Severe Heat Illness

Seizures

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Seizures can occur in severe cases of heat-related illness, particularly heatstroke, when the body's temperature rises to dangerously high levels. Extreme heat can disrupt normal brain function, leading to confusion, loss of consciousness, and convulsions. Although uncommon, seizures are a medical emergency and indicate that immediate treatment is required.

Rhabdomyolysis

Rhabdomyolysis is a serious condition that can develop when extreme heat and physical exertion cause muscle tissue to break down. As damaged muscle fibres enter the bloodstream, they can place significant stress on the kidneys and potentially lead to kidney injury. Symptoms may include severe muscle pain, weakness, swelling, and dark-coloured urine. Prompt medical attention is essential to prevent serious complications, according to the CDC.

Skin Conditions

Heat rash/Sunburn

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Prolonged exposure to heat and sunlight can lead to a range of skin-related conditions. Heat rash occurs when sweat becomes trapped beneath the skin due to blocked sweat ducts, causing small red bumps, itching, and irritation. Sunburn, on the other hand, results from excessive exposure to ultraviolet (UV) radiation and is characterised by redness, pain, tenderness, and, in severe cases, blistering of the skin. Although often considered minor conditions, both can cause significant discomfort and may indicate prolonged exposure to extreme heat and sunlight.

These heat-related illnesses are largely preventable. Awareness, early recognition of symptoms, and prompt action can save lives during heatwaves.

Disclaimer: The information provided in this article is for general informational and educational purposes only and is not intended as a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or a qualified healthcare provider with any questions you may have regarding a medical condition.