Hot Weather and Varicose Veins: Why Summer Can Increase Blood Clot Risks and 4 Ways to Stay Safe

Summer heat can be enjoyable, but for people living with varicose veins, rising temperatures may also bring added health concerns. While varicose veins are often viewed as a cosmetic issue, medical experts warn that hot weather, dehydration, and prolonged inactivity can increase the risk of blood clots in some individuals.

In this article, we explain how heat affects varicose veins, why blood clot risks may increase during hot weather, the warning signs you should never ignore, and four practical steps to help reduce your risk.

What Are Varicose Veins?

Varicose veins are enlarged, swollen, and twisted veins that typically appear on the legs and feet. They develop when tiny valves inside the veins become weak or damaged, allowing blood to flow backward and pool instead of moving efficiently toward the heart.

The condition is extremely common. According to the UK Vein Clinic, up to 20 million people in the United Kingdom experience varicose veins at some point in their lives.

For many people, symptoms are mild and include:

• Aching or heavy legs
• Swollen ankles
• Visible blue or purple veins
• Itching around the affected veins
• Muscle cramps, especially at night

However, in more severe cases, untreated varicose veins may contribute to skin changes, leg ulcers, and an increased risk of blood clots.

Why Hot Weather Can Make Varicose Veins Worse

Warm temperatures naturally cause blood vessels to expand. This helps the body release excess heat but also places additional strain on already weakened veins.

According to Professor Mark Whiteley, a venous surgeon and founder of The Whiteley Clinic, hot weather causes veins to dilate, making them more visible and allowing blood to pool more easily in damaged veins.

When blood circulation slows, the possibility of clot formation may increase, particularly when combined with dehydration and reduced movement.

How Heat, Dehydration, and Inactivity Increase Blood Clot Risk

Several summer factors can work together to raise clotting risks.

1. Dehydration Thickens the Blood

During hot weather, the body loses more water through sweating. Without enough fluid intake, blood becomes more concentrated, making it easier for clots to develop.

Alcohol and excessive caffeine may also contribute to dehydration if they replace adequate water intake.

2. Reduced Movement Slows Circulation

Many people spend long periods sitting indoors during heatwaves or while traveling.

Remaining in one position for extended periods slows blood flow in the legs, creating conditions that may encourage clot formation.

3. Varicose Veins Already Affect Blood Flow

Because varicose veins interfere with normal circulation, combining them with dehydration and inactivity may further increase the likelihood of complications.

Although most people with varicose veins never develop dangerous blood clots, experts advise taking extra precautions during periods of extreme heat.

Four Ways to Reduce Your Risk During Hot Weather

Stay Well Hydrated

Proper hydration is one of the simplest ways to support healthy circulation.

Aim to drink water consistently throughout the day instead of waiting until you feel thirsty. Water remains the best choice, although diluted fruit juice, herbal tea, and low sugar drinks can also contribute to daily fluid intake.

Many health experts recommend approximately six to eight glasses of fluids daily, though individual needs vary depending on activity levels and weather conditions.

Keep Moving

Even gentle movement helps blood circulate through the legs.

If you work at a desk, travel frequently, or spend long periods watching television, make it a habit to:

• Walk every hour
• Stretch regularly
• Flex your ankles and calves while sitting
• Take short standing breaks throughout the day

These simple movements encourage blood flow and reduce prolonged pooling in the veins.

Avoid Overheating

Keeping your body cool can reduce stress on your circulatory system.

Helpful strategies include:

• Staying in shaded areas during peak afternoon heat
• Using fans or air conditioning whenever possible
• Wearing loose, lightweight clothing
• Taking cool or lukewarm showers
• Applying cool cloths to help lower body temperature

Whenever possible, schedule outdoor exercise during the early morning or evening instead of the hottest part of the day.

Limit Alcohol During Heatwaves

Alcohol can contribute to dehydration, especially during periods of extreme heat.

If you choose to drink alcohol, balance it with plenty of water throughout the day to help maintain hydration.

Warning Signs of a Blood Clot

Although blood clots are relatively uncommon, recognizing symptoms early can be lifesaving.

Symptoms of deep vein thrombosis (DVT) may include:

• Throbbing pain in one leg
• Swelling in one leg
• Warm skin around the affected area
• Red, blue, or darkened skin
• Enlarged or swollen veins

These symptoms usually occur in the calf or thigh but can also affect the arm.

If you notice these symptoms, seek prompt medical assessment.

Emergency Symptoms That Require Immediate Medical Attention

A blood clot can become life threatening if it travels to the lungs, causing a pulmonary embolism.

Seek emergency medical care immediately if you experience:

• Sudden shortness of breath
• Chest pain
• Difficulty breathing
• Coughing up blood
• Rapid heartbeat
• Fainting or severe dizziness

These symptoms require urgent medical evaluation.

Who May Be at Higher Risk?

Some people have additional risk factors that increase the likelihood of developing blood clots.

These include:

• Previous DVT or pulmonary embolism
• Pregnancy or recent childbirth
• Existing varicose veins
• Recent surgery or major injury
• Cancer or cancer treatment
• Hormone replacement therapy
• Certain birth control medications
• Age over 60
• Extended periods of immobility
• Family history of blood clots

Having one or more of these factors does not mean a clot will occur, but it does make preventive measures more important.

When Should You See a Doctor?

Speak with a healthcare professional if your varicose veins become increasingly painful, swollen, or begin causing skin discoloration or ulcers.

You should also seek medical advice if you notice new swelling in one leg or symptoms that suggest a possible blood clot.

Early evaluation can help prevent serious complications and determine whether additional treatment is needed.

Final Thoughts

Varicose veins are common and are often harmless, but hot summer weather can place additional strain on the circulatory system. Heat causes veins to expand, dehydration thickens the blood, and prolonged sitting slows circulation. Together, these factors may increase the risk of blood clot formation in susceptible individuals.

Fortunately, simple habits such as staying hydrated, moving regularly, avoiding overheating, and limiting alcohol intake can help support healthy circulation during warm weather.

If you experience symptoms of deep vein thrombosis or signs of a pulmonary embolism, seek immediate medical attention. Early diagnosis and treatment can be lifesaving.

Sources

• NHS. Deep Vein Thrombosis (DVT): https://www.nhs.uk/conditions/deep-vein-thrombosis-dvt/
• NHS. Pulmonary Embolism: https://www.nhs.uk/conditions/pulmonary-embolism/
• The Sun (July 28, 2026).

Disclaimer

This article is for informational and educational purposes only and should not be considered medical advice. It is not intended to diagnose, treat, cure, or prevent any medical condition. Always consult a qualified healthcare professional regarding any medical concerns or symptoms. If you experience symptoms of a blood clot, including sudden chest pain, shortness of breath, or swelling and pain in one leg, seek emergency medical attention immediately.