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Heat edema: Why do my legs swell up in the summer?

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DefinitionWhy it happensIs it dangerous?TreatmentsPreventionSummary
For some people, heat and humidity cause legs to swell. The condition is called edema. Depending on the underlying cause, medical treatments and home remedies may help ease heat edema.
Medically reviewed by Debra Sullivan, Ph.D., MSN, R.N., CNE, COI
Written by Amy McLean
Updated on September 27, 2023

If you experience symptoms of heat edema, it is best to contact a doctor for advice. They can determine whether an underlying condition is causing your symptoms and advise on suitable medications and other treatments.

What is heat edema?

A person is sitting on a bed and holding their knee.
Photography by AsiaVision/Getty Images

Heat edema is a hyperthermic condition that occurs in response to an increase or change in heat and humidity. It typically affects the distal extremities — parts of the body furthest away from the center, like the legs and feet.

As blood vessels widen and fluid collects in the distal extremities, it can cause symptoms such as swelling.

Edema can be a diagnosis on its own, but it is usually a symptom of another condition.

Why do I swell more in the heat?

You may find that you swell more in the heat, as hotter weather can cause blood vessels to dilate. There is an increase in the blood supply to the skin, and fluid moves into the tissues, causing swelling.

Swelling can also happen in hotter climates as your body attempts to regulate its core temperature to reduce the risk of organ damage. The heart directs the blood away from organs such as the kidneys and intestines, causing it to pool in extremities such as the legs instead.

Is heat edema dangerous?

In some cases, heat edema may resolve on its own as your body adjusts to the increase in temperature.

However, edema may also be due to an underlying medical condition that may need treatment. Your doctor can help you identify any factors contributing to or worsening heat edema.

Conditions that can cause edema include:

  • cellulitis
  • cirrhosis
  • congestive heart failure
  • deep vein thrombosis (DVT)
  • kidney disease
  • liver failure
  • lymphedema
  • severe, long-term protein deficiency
  • thyroid issues
  • venous insufficiency (damaged vein valves)

Pulmonary edema is the only type of edema that requires immediate treatment. This is because it can be life threatening. It causes fluid to build up in the lungs and can cause symptoms such as:

  • swelling in the ankles or feet
  • breathing difficulties
  • skin that looks pale or bluish
  • sweating or clammy skin
  • coughing up sputum
  • feeling of suffocation
  • confusion

However, some conditions, such as DVT, can lead to life threatening complications without early diagnosis and treatment. It is best to contact a doctor as soon as possible to determine the cause of heat edema and begin any necessary treatments.

How to treat edema

If your edema is due to an underlying medical issue, treating the condition may help reduce it.

A doctor may also recommend medical treatments and home remedies.

Prescription medications to treat edema

A doctor may prescribe medication to directly treat heat edema.

They may recommend loop diuretics in cases of liver disease, kidney disease, and congestive heart failure.

If you have cirrhosis with secondary hyperaldosteronism, a condition where the adrenal glands release too much aldosterone, your doctor may recommend spironolactone (Aldactone, Carospir) and furosemide (Lasix, Furoscix).

If you have DVT, your doctor may prescribe anticoagulants. Anticoagulants help to prevent blood clots. Types include:

Your doctor can advise which prescription medication they recommend and what it involves.

Your doctor may also prescribe compression stockings for conditions such as lymphedema. However, it is important to make sure that stockings don’t cause you to overheat when you’re spending time in a warm environment.

Over-the-counter (OTC) medications are not available for treating edema. OTC diuretics may not be beneficial for treating edema.

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Nonmedical ways to treat edema

There are various steps you can take to reduce heat edema. These include:

  • drinking plenty of water and keeping cool to reduce edema that occurs due to warmer temperatures
  • keeping your legs elevated to help the blood flow back to your body’s core
  • taking part in gentle exercise or physical activity to encourage blood flow
  • wearing comfortable shoes and loose clothing
  • avoiding foods high in salt

How to prevent edema

Depending on the underlying cause, it may not be possible to completely prevent edema.

Heat edema may resolve on its own as your body adjusts to the warmer environment. However, various steps can help you reduce the risk of edema occurring or recurring. These are similar to home remedies for edema and include:

  • avoiding consuming a diet high in salt
  • getting enough physical activity or gentle exercise to encourage blood flow
  • maintaining a moderate weight
  • taking any medication your doctor prescribes for edema or conditions that can cause it

Your doctor can also advise on ways to reduce the risk of edema.

Summary

Heat edema typically occurs when heat and humidity cause swelling in the distal extremities, such as the legs and feet. In some cases, edema may resolve as the body gets used to the change in climate. However, it may be necessary to treat an underlying condition.

Conditions that can cause edema include cellulitis, congestive heart failure, kidney disease, and liver failure. Contacting a doctor as soon as you have concerns about edema can allow them to diagnose the cause and recommend a treatment plan as early as possible.

Your doctor may recommend prescription diuretics for heat edema. Home remedies can also help reduce edema. These include keeping cool, gently exercising to encourage circulation, and keeping your legs elevated.

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