Yes, high temperatures can put a serious strain on your heart. Hot weather causes your blood pressure to drop, forces your heart to work harder to pump blood around your body, and increases the risk of dehydration and heart rhythm disturbances. This article explains why heat can be dangerous for your heart and how you can protect yourself on warm days.

What does heat do to your heart?

The warm summers we’re experiencing more frequently these days aren’t easy on our bodies. To release all that extra heat through the skin, our blood vessels widen. This is a natural response from the body, but it does have consequences for your heart. For example, your blood pressure can drop, making you more prone to dizziness. Your heart also has to work harder to pump blood throughout the body. Your heart can work up to two to even four times harder on a hot day compared to a day with moderate temperatures.

In warm weather, you also tend to sweat more. This can make your blood thicker, which in turn increases the risk of clotting. If you already have early-stage narrowing in your blood vessels, this can unfortunately lead to sudden blockages and, in the worst case, even a heart attack.

Can hot weather cause cardiac arrest?

Your heart functions through electrical signals. In hot weather, your heart tends to beat faster, making it more susceptible to disruptions in this electrical system. Sometimes this is harmless—like the heart skipping a few beats—but it can also lead to more serious arrhythmias and, in rare cases, cardiac arrest. Dehydration can also contribute to an irregular heartbeat and, in severe cases, trigger arrhythmias and cardiac arrest.

What does research say about cardiac arrest caused by heat?

More people die from cardiovascular diseases in winter than in summer. This is supported by scientific studies. For example, research published in Science of the Total Environment found that 1.5% of the cardiac arrest deaths examined could be linked to hot weather, while extremely cold weather contributed to over 12% of these cases. Still, high temperatures are far from risk-free. The study also notes that warm nights can be particularly hazardous.

Moreover, a large-scale study published in The Lancet Regional Health – Western Pacific shows that high temperatures and heatwaves significantly contribute to the occurrence of sudden cardiac arrest outside of hospital settings.

How do you recognize a heart problem in hot weather?

Always stay alert when experiencing symptoms, especially if you have a history of heart issues and the weather is very warm. Watch out for signs such as:

• Chest pain or pressure (possibly radiating to the left shoulder or arm)
• Heart palpitations
• Dizziness or lightheadedness
• Shortness of breath or difficulty breathing
• Fainting
• Nausea and vomiting
• Pale or grayish skin tone
• Extreme fatigue

If you have a heart condition and experience dizziness, palpitations, or shortness of breath on a hot day, don’t hesitate to call a doctor. If you experience sudden chest pain, call emergency services immediately (999).

Quick action can be crucial in such situations, highlighting the importance of preparedness and public knowledge about resuscitation and AEDs.

What else should you watch out for during a heatwave?

Some signs of heart problems resemble symptoms of heat exhaustion or the more serious heat stroke. With heat exhaustion, you may experience cramps, a rapid heartbeat, heavy sweating, and pale skin. You may also faint. In this case, it’s important to cool your body down, for example, by taking a cold shower and to drink small sips of water.

A heat stroke is even more serious. Your body temperature rises above 39 degrees Celsius, your heart rate is high, you feel nauseous, your skin turns red, and you may experience seizures or even lose consciousness. In this case, always call emergency services (999)!

What can you do to prevent heart problems caused by heat?

Hydration is essential

Make sure to drink plenty of water to avoid dehydration from excessive sweating. This is one of the most important things you can do yourself. It is recommended to drink at least 2.5 liters of water per day when the temperature exceeds 25 degrees Celsius. Drinks that are considered very suitable in hot weather include: 

• Water 
• Unsweetened tea 
• Heavily diluted lemonade syrup
• Dairy products, such as unsweetened yogurt and buttermilk

Eat foods that are rich in electrolytes, emphasizes the Oklahoma Heart Hospital in an article. These include bananas, leafy greens, and yogurt.

Seek cool environments and adjust your activities

• Find shade—especially during the hottest part of the day, between 12:00 and 16:00.Use a fan when possible and close your windows and curtains when it’s warmer outside than inside. 
• Wear airy clothing. 
• It’s good to stay active, but preferably do so in the morning or evening when it’s cooler outside. 

Pay close attention to any symptoms and drink plenty of water.

Extra risk for heart patients during heat: what to watch out for

Heart patients are recommended the following:

• Some people with heart problems retain too much fluid because the heart pumps blood less effectively. Sometimes, doctors advise these individuals to drink less. If that applies to you, it’s important to first consult your doctor during hot weather to see whether you may drink more.
• If you take diuretics for high blood pressure or to get rid of excess fluid, this may be too much during heat. If in doubt, consult your doctor.
• Make sure your medications don’t get too warm. Most medications should be stored in a dry cabinet that doesn’t exceed 25 degrees Celsius. 
• Is someone near you especially vulnerable? Make sure someone regularly checks how that person is doing.

Hot weather requires extra attention for your heart, especially if you have a heart condition. Hopefully, after reading this blog post, you have a clearer picture of the risks and what you can do yourself to prevent symptoms. Make sure you drink enough, seek out cool places, and take regular breaks. Stay alert to signals from your body, and always contact a doctor if you’re unsure. Because prevention is, and always will be, better than cure.

Would you like to know more about recognizing cardiac arrest and how to act in such a situation? Then read our article about the different types of cardiac arrest.