Hot weather and your heart

A family having a picnic Summer is definitely here, and while many of us have been longing for the hot weather, it's still important to look after yourself in the heat.

How does hot weather affect my heart?

When the weather is hot you sweat to cool down, but this means that you lose more fluid than usual from your body. This can drop your blood pressure and make your heart beat faster. This is not a problem for most people as long as they drink plenty of fluids, like water or other sugar-free drinks to keep from getting dehydrated.

However, if you have a heart problem, extreme heat may place an extra burden on your heart and circulation, so it’s particularly important to stay cool and look after yourself. 

What can I do to keep cool?

  • Keep hydrated by drinking plenty of water or other sugar-free drinks (Though if you've been told to restrict your fluid intake for medical reasons you should speak to your GP)  
  • Avoid drinking too many alcoholic or caffeinated drinks.  Caffeine-based drinks can cause you to lose more fluid from your body.
  • Eat cold foods, particularly salads and fruit with a high water content.
  • Make sure your home is cool when you're staying indoors.
  • Wear light, loose-fitting cotton clothes.
  • Stay out of the heat in the hottest part of the day between 11am and 3pm.
  • If you have to go out in the heat, walk in the shade, apply sunscreen and wear a hat 
  • Avoid extreme physical exertion. 

Hot weather and heart conditions

Angina

If you have coronary heart disease, you may find you start to experience angina or your angina worsens during hot weather, because hot weather increases the workload on your heart and the demand for oxygen, especially when you are more active. 

Heart failure

It’s particularly important to stay cool if you have heart failure - where your heart doesn't pump as well as it should. If you’ve been told to restrict your fluid intake, speak to your GP about other ways to keep cool during summer.  If you take water tablets and start to feel dizzy or light headed let your doctor know. Your dose can then be reduced or stopped for a little while, if needed, until you feel better.

Heat stroke

Losing too much body fluid can increase your internal body temperature, which could be life-threatening if left untreated. 

Symptoms of heat stroke include sweating, cold clammy skin, dizziness, fainting, muscle cramps, heat rash, oedema (swelling) in the ankles, shallow or fast breathing, nausea and vomiting. 

If you suspect that you or someone else has heat stroke, get medical attention immediately.

Who is most at risk?

Elderly people and very young children have more difficulty in regulating their temperature and so can be more at risk from extreme temperatures. In hot weather, check on your friends and relatives regularly to make sure they are cool and comfortable.

Read our information sheet on travel and your heart.