As temperatures soar during a heat wave, the effects go far beyond sweaty clothes and sunburn. Extreme heat can be dangerous, especially for people with pre-existing health conditions, the elderly, and young children. It’s not just about staying cool — it’s about understanding how the body reacts to high temperatures and how heat can intensify certain health issues. Here are five health conditions that can worsen in a heat wave, including how dangerously high temperatures can lead to life-threatening emergencies like heart attacks and strokes.
1. Heart Disease and Heart Attacks
When the body is exposed to high heat, it works harder to cool itself. This causes the heart to pump faster and harder, especially when dehydration sets in. For people with heart conditions — such as coronary artery disease or congestive heart failure — this extra strain can be dangerous.
How heat triggers heart attacks:
During extreme heat, the body redirects blood flow toward the skin to help cool you down, placing more stress on the heart. Dehydration thickens the blood, increasing the risk of blood clots and potentially triggering a heart attack. Even otherwise healthy individuals are at risk if they overexert themselves in the heat, such as during outdoor exercise or physical labor without hydration breaks.
2. Stroke
Just like heart attacks, strokes can be brought on or worsened during a heat wave. When the body becomes dehydrated, blood pressure can drop or fluctuate unpredictably. If someone already has underlying vascular issues, heat stress can push their system over the edge.
How heat increases stroke risk:
Heat waves can impair the body’s ability to regulate temperature, particularly in the elderly. When core body temperature rises rapidly (a condition called heat stroke), it can damage brain cells and disrupt blood flow to the brain. Additionally, the thickened blood due to dehydration increases the risk of clots forming — which can lead to an ischemic stroke, the most common type.
3. Respiratory Diseases (Asthma and COPD)
Air quality tends to worsen during heat waves, especially in urban areas where pollution levels can spike. This is bad news for people with asthma, chronic obstructive pulmonary disease (COPD), or other respiratory conditions.
Why heat makes breathing harder:
Hot air can increase ozone levels and trap pollutants close to the ground. This polluted air can irritate the lungs, trigger asthma attacks, and worsen symptoms of COPD. People may experience wheezing, shortness of breath, or increased need for medication during heat waves. Indoors, improper ventilation or overheating can also make breathing more difficult.
4. Kidney Disease and Dehydration
People with kidney problems are highly vulnerable during heat waves because dehydration can rapidly worsen kidney function. The kidneys need water to help filter waste from the blood and keep electrolyte levels balanced. Even healthy kidneys can be stressed by dehydration, but for those with chronic kidney disease (CKD), the effects can be much more severe.
The danger:
When you sweat excessively and don’t rehydrate properly, your kidneys receive less blood flow, which impairs their ability to work. In extreme cases, this can lead to acute kidney injury or accelerate the progression of chronic kidney disease. People on dialysis or certain medications (like diuretics) are at even greater risk.
5. Diabetes
Managing blood sugar levels becomes more difficult during extreme heat. People with type 1 or type 2 diabetes need to be especially cautious in a heat wave, not only because of their body’s reduced ability to cool itself but also because heat can interfere with medications and insulin.
How heat affects diabetes:
Dehydration can cause blood sugar levels to rise. Moreover, high temperatures can alter how insulin is absorbed and how effective certain diabetes medications are. If insulin is not stored properly (it can become unstable in heat), its potency may be compromised, leading to poor glucose control. In some cases, heat can lead to diabetic emergencies, like ketoacidosis or hypoglycemia, especially if food and fluid intake are affected.
Final Thoughts
Heat waves are more than uncomfortable — they’re potentially deadly, especially for people with underlying health conditions. Heart attacks and strokes are among the most severe risks, but respiratory issues, kidney disease, and diabetes complications are also major concerns.
To stay safe during extreme heat:
- Drink plenty of water.
- Stay indoors or in shaded, cool areas.
- Avoid strenuous activity during the hottest parts of the day.
- Check in on elderly family members or neighbors.
- Keep medications stored properly and monitor any chronic conditions closely.
The key is awareness and preparation. Recognize the warning signs of heat-related illness, listen to your body, and don’t underestimate how dangerous high temperatures can be — because when it comes to your health, every degree matters.
