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How heat can increase stroke risk

A woman sits on a yoga mat in her living room, drinking from a water bottle.

May 23, 2024—We're heading into summertime, when the living should be easy. But the weather is warming, and experts predict that much of the U.S. will see above-average temperatures this summer. That can lead to heat illness and other serious health effects—including an increased risk of stroke.

How heat affects your body

Your heart has a good mechanism for cooling your body: It pumps more blood, directing it to just under your skin. This, along with sweating, helps your body release heat.

When it's hot, your heart has to work harder to regulate your body temperature. According to the American Stroke Association (ASA), that extra effort can lead to sudden, serious and even fatal health problems like acute ischemic stroke, which is the most common kind of stroke.

People with heart disease or other health conditions may face an additional risk. Some prescription and over-the-counter medications used to treat cardiovascular disease (CVD), pain and allergies can interfere with your body's ability to cool itself.

Extreme heat also can trigger heart attacks, heart failure, arrhythmia (irregular heartbeat) and other types of CVD, says the Centers for Disease Control and Prevention (CDC). Air pollution, such as smoke from wildfires, can lead to or worsen CVD too.

Keeping cool

Heat can affect anyone. But, according to CDC and the ASA, the risk may be higher for people who:

  • Are 60 or older—especially if they don't have air conditioning.
  • Have heart disease.
  • Have high blood pressure.
  • Have a history of stroke.
  • Are obese.

If you're at risk for a heat-related stroke or heart problem, your doctor can offer advice to help you stay safe and healthy during summer's hottest days.

That might include these hot-weather tips:

Stay hydrated throughout the day. Water is best; your heart needs plenty of water to pump blood effectively. Avoid caffeine and alcohol.

Use air conditioning, fans or both. If you don't have air conditioning, go somewhere that does, like a library, a cooling shelter or a friend's house.

Dress appropriately. Loose-fitting, light-colored and lightweight clothes can help keep you from overheating. If you're outside, include a hat and sunglasses.

Wear sunscreen. Pick one with an SPF of at least 30 and that protects your skin from both UVA and UVB rays.

Don't overdo it. Save exercise, yard work and other activities for the coolest parts of the day.

Know the signs of heat-related illness. Learn the difference between heat exhaustion and heatstroke and how to prevent them.

Think you already know the facts? Take our heat illness quiz to find out.

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