What causes varicose veins? Understanding the underlying factors

Most people recognise varicose veins by their bulging, rope-like appearance. What many people do not know is why they form in the first place. In simple terms, varicose veins develop when blood flow in the legs becomes less efficient and pressure builds up inside the veins. In reality, the reasons behind that pressure are often more complex and usually develop gradually over time.

In this article, we explain how varicose veins develop, what increases your risk, and what you can do to reduce the likelihood of them getting worse.

How do varicose veins form?

Veins in the legs contain small one way valves that help blood flow upward toward the heart. These valves open to allow blood to move in the right direction and close to prevent it from flowing backwards. When the valves weaken or become damaged, blood can leak back down into the vein.

As blood begins to pool, pressure inside the vein increases. Over time, the vein walls stretch, lose elasticity, and become enlarged or twisted. This is when varicose veins start to become visible and symptoms may begin.

This process is known as chronic venous insufficiency and it is the underlying condition behind most cases of varicose veins.

You can learn more about this mechanism in our article on venous insufficiency: symptoms, causes, and treatments.

Why do varicose veins appear in the legs?

The veins in your legs have a harder job than veins elsewhere in the body. They must carry blood upward against gravity, often over a long distance. When you sit or stand for long periods, blood flow slows and pressure in the leg veins increases.

The veins in the lower legs are also longer and more exposed to pressure changes than veins in other parts of the body. Even mild valve weakness is more likely to cause symptoms here first.

You can read more about these early changes in our article on early-stage varicose veins symptoms.

Key causes and risk factors

Varicose veins rarely develop for just one reason. In most people, several factors work together over time to increase the risk.

• Genetics
  If one or both of your parents had varicose veins, your own risk is significantly higher.
• Hormonal changes
  Pregnancy, menopause, and hormonal medications can weaken vein walls and valves.
• Age
  As you get older, vein walls become less elastic and valves may no longer close as effectively.
• Gender
  Women are more likely to develop varicose veins, partly due to hormonal influences and pregnancy-related changes.
• Occupation
  Jobs that involve long periods of standing or sitting, such as healthcare, teaching, retail, or office work, increase pressure in the leg veins.
• Weight
  Extra weight places additional strain on the venous system and can make symptoms more noticeable.
• Lack of movement
  Prolonged sitting or standing slows circulation and makes it harder for the veins to push blood upward.

For practical steps that may help reduce strain on your veins, see our guide on how to avoid varicose veins.

Are all varicose veins visible?

Not all varicose veins are visible on the surface of the skin. Some affected veins lie deeper and may not be immediately noticeable. These are sometimes referred to as hidden or internal varicose veins.

Even without visible veins, symptoms can still occur. These may include aching or heavy legs, night cramps, swelling around the ankles, or itching and burning sensations.

If these symptoms sound familiar, our article on hidden varicose veins symptoms explains what to look for and when to act.

When should you seek medical advice?

If you experience persistent leg discomfort, swelling, visible veins, or changes in the skin around your ankles or lower legs, it is sensible to have your veins assessed.

A simple ultrasound scan can show whether blood is flowing in the correct direction and whether the vein valves are working properly. This helps determine whether treatment would be beneficial.

You can learn more about what happens during an assessment in our guide to a consultation at UK Vein Care.

Wondering about treatment prices?

Treatment costs depend on how many veins are affected and which treatment method is recommended. Our page on UK varicose veins treatment cost explains what influences pricing and what is included in your care.

‍