What is Heat Edema?

Heat edema is a swelling of the extremities associated with exposure to high temperatures. It most commonly occurs during a heat wave, when the temperature is unusually high, or when someone accustomed to a cool or temperate climate visits a hot one. This condition itself is not dangerous, but it can be a sign that a person could be at risk for a more serious heat-related illness, such as heatstroke. There are a number of measures people can use to prevent and address heat edema.

This condition occurs when the body starts to retain water and have trouble excreting salt. It is believed to be linked to an increase in the hormone aldosterone. Heat edema can set in after a day or more in an unusually warm climate, or it can onset more quickly in people who are working outdoors or engaging in heavy physical activity.

People usually notice that rings and other jewelry feel tight. Heat edema is often accompanied with flushing of the face. Garments may feel restrictive, the patient usually sweats, and there is generally a sensation of being hot and uncomfortable.

Immediate treatment for heat edema involves getting the patient into a cool place, providing cold fluids to drink, and elevating the extremities to reduce swelling. The edema can resolve very quickly in a location like an air conditioned building, helping the patient to feel more comfortable. This will also prevent heatstroke and more serious heat-related illnesses.

Allowing people to acclimate slowly to the effects of heat can reduce the risk that heat edema will develop. If the weather is hot, people should try to spend time in cool places and should work or engage in physical activity in bursts, and not during the hottest part of the day, to give their bodies a chance to adjust. People who are traveling to a hot climate should bring layers of clothing so they can dress down for the heat, and should make sure that they have access to a cool place to rest if they start to feel too hot.

If the weather is hot and someone reports feeling dizzy or confused, is slurring words or stumbling, or is behaving abnormally in other ways, that person should be brought to a hospital for treatment for heatstroke. Heatstroke can onset very suddenly and people have varying degrees of sensitivity to heat. Thus, some people may be fine in certain temperatures, while others may be at risk of heatstroke.