Swollen Legs & Feet During a Heat Wave

For many people, summer days bring memories of barbecues, pools, beaches and lazy afternoons. But during prolonged periods of abnormally hot weather, unfortunate health problems can occur. During heat waves, many people experience excessive water retention, or heat-related edema. Because of the effect of gravity, the swelling becomes more pronounced and obvious in the feet, ankles and legs. Although usually temporary, swollen legs can be an uncomfortable side effect of summer heat. While attention and care may prevent this summer hazard, medical attention may be needed in some situations.

Swollen Legs & Feet During a Heat Wave (Image: pashapixel/iStock/Getty Images)

Why It Occurs

Heat can cause temporary dilation blood vessels, but the overheated body can also have trouble bringing all the blood from the extremities back to the heart. As a result, fluid can pool in the legs and feet. This extra fluid can make your skin tight and shiny and also cause swelling in the hands and fingers. A sure sign you have edema is when an indentation remains after you press your finger into your swollen skin for several seconds. According to the Centers for Disease Control and Prevention (CDC), heat edema tends to occur when the body is not already acclimated to the hot environment.

Risk Factors

Heat-related edema of the extremities is typically not serious, but it can be a first sign of a more severe form of heat-related illness, such as heat exhaustion. Certain medical conditions make people susceptible to fluid retention, including severe lung, kidney, liver and heart disease. Older adults, pregnant women and people who are overweight are more prone to water retention, particularly if they sit or stand for long intervals. But even young, healthy athletes, military personnel or other people who are involved in strenuous outdoor activities are at risk for heat-related illness if exposed to prolonged hot and humid environments. Anyone at risk may want to take extra precautions to prevent this occurring during hot weather.


Swelling in the legs can typically be relieved by home care. Elevating the legs helps counter the effects of gravity on the feet, ankles and legs, allowing normal blood and fluid return from the extremities to the heart. Exercise improves blood flow and also helps return the blood from your legs and feet back to your heart. Brief walking and simple leg movements can ease the swelling. Support stockings may also reduce swelling. If your swelling is triggered by a medical condition, communicate with your doctor about other ways to relieve your edema.


To prevent heat-related swelling, avoid the extreme heat as much as possible. Keeping the body cool can minimize the dilation of blood vessels and prevent the accumulation of fluids in the legs. Drink plenty of fluids to prevent dehydration. If you have to work outdoors in a hot environment or during a heat wave, take frequent breaks to cool down and gradually acclimate yourself to the weather. Equally important, avoid prolonged sitting or standing. Immobility causes fluids to pool in the feet, ankles and legs. If a situation such as a long car, train or plane ride requires prolonged sitting, it is important to take brief exercise breaks. If walking is not possible, doing leg or calf raises can help.

When to Seek Medical Treatment

Even though heat-related swelling can be temporary and seemingly minor, it may also be an early sign of heat-related illness which, if allowed to progress, can lead to heat exhaustion or a fatal heat stroke. Leg edema can also signal that a medical condition requires more aggressive treatment. Swelling related to certain medical problems, such as severe kidney or liver disease, responds well to restricting sodium and fluids, for example, so be sure to discuss necessary restrictions and your symptoms with your doctor. If you suffer any injury to the skin that covers the swollen leg or foot, or if any fluid is oozing out, see your doctor. Also contact your doctor if you have a sudden increase in swelling, or if you have edema for no apparent reason. Seek immediate medical care if you have fever, redness, warmth or pain in the leg, or if you have chest pain, difficulty breathing or confusion.

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