For many individuals, the appearance of varicose veins raises questions about what has caused them and whether they might become worse over time. Understanding why they develop is the first step towards managing symptoms and knowing when to seek professional advice.
How healthy veins work
Healthy veins have an important job. They carry blood back to the heart after it has delivered oxygen to the body. In the legs, this job is more demanding because the blood must travel upwards against gravity.
To make this possible, the body relies on several key mechanisms:
- One-way valves inside the veins keep blood moving in the correct direction and prevent it from flowing backwards.
- Calf muscles act as a natural pump. When you walk or move your legs, the muscles squeeze the veins and push blood upwards.
- Elastic vein walls help maintain steady blood flow by allowing veins to expand and contract as needed.
When these systems work together efficiently, blood circulates smoothly, and pressure inside the veins stays balanced.
What happens in varicose veins
Varicose veins develop when the normal flow of blood in the legs becomes disrupted. This usually begins with a weakness in the vein walls or a problem with the one-way valves that help direct blood upwards.
Several changes then occur inside the affected vein:
- The valves stop closing properly, which allows blood to fall back down the leg rather than continuing towards the heart.
- Blood begins to pool in the vein, creating a build-up of pressure.
- The vein stretches and widens, which causes it to twist, bulge, and become more visible under the skin.
These changes can lead to symptoms such as aching, heaviness, or swelling in the legs, particularly after long periods of standing or sitting.
Main causes and risk factors
Genetics and Family History
A family history of varicose veins is one of the strongest predictors of developing them. Some people inherit weaker vein walls or valves, which makes it easier for blood to flow backwards and increases the likelihood of varicose veins appearing over time.
Ageing
As we get older, the structures within our veins naturally become less resilient. The valves may not close as tightly, and the vein walls can lose some of their elasticity. These age-related changes make it harder for blood to travel upwards, which raises the risk of varicose veins.
Hormones and Sex
Women experience varicose veins more often than men due to hormonal influences. Hormones such as oestrogen and progesterone can relax vein walls, especially during pregnancy, while using contraceptive pills or hormone replacement therapy may also contribute to increased vein pressure.
Pregnancy
During pregnancy, the amount of blood circulating in the body increases and hormone levels change significantly. These adjustments place additional strain on the veins. The growing uterus can also press on the veins in the pelvis and legs. Some pregnancy-related varicose veins improve after birth, but others may persist.
Weight and Lifestyle
Carrying excess weight puts more pressure on the leg veins and can make valve function less effective. Long periods of sitting or standing at work can also reduce the natural pumping action of the calf muscles. Low activity levels further increase the risk by slowing overall circulation in the legs.
Previous Leg Injury or Blood Clots
A significant leg injury or a past deep vein thrombosis can damage the valves inside the veins. Once these valves are weakened, the vein cannot regulate blood flow as effectively. This can lead to long-term reflux of blood and the development of varicose veins.
Other Contributing Factors
Activities or conditions that repeatedly increase pressure inside the abdomen can influence how well blood returns from the legs. Chronic constipation and heavy lifting are two common examples. Over time, these pressures can place additional strain on the veins and impair their function.
Common myths about varicose veins
“Crossing your legs causes varicose veins.”
This is a widespread belief, but it is not accurate. Crossing your legs does not damage the valves inside your veins and is not a cause of varicose veins.
“Varicose veins mean you have poor circulation.”
Varicose veins are caused by valve weakness rather than a general circulation problem. Most people with varicose veins have normal arterial circulation.
“Only older people get varicose veins.”
Ageing increases the risk, but younger adults can also develop varicose veins, especially if they have a family history or other contributing factors.
When varicose veins become a concern
Varicose veins are often harmless, but there are situations where they may indicate a more significant problem.
You should consider seeking medical advice if you notice any of the following:
- Persistent aching or heaviness in the legs, especially towards the end of the day
- Swelling around the ankles or lower legs that worsens after standing
- Changes in the skin, such as dryness, itching, darkening, or hardening
- Tender or hardened veins that feel sore to touch
- Bleeding from a vein, even if it stops quickly
- Ulcers or wounds near the ankle that are slow to heal
These signs may indicate that the veins are under increased pressure and not functioning as they should. Early assessment can help prevent symptoms from progressing.
Concerned about veins in your legs?
At Southwest Veins, we offer a free, no-obligation consultation where you can discuss your concerns with an experienced specialist. You will receive clear advice, a personalised assessment, and guidance on the best next steps. Arrange a video consultation using our confidential online form.
Jamie Barwell is a Consultant Vascular Surgeon who has treated over 1000 patients with varicose vein problems, using open surgical techniques and, since 2007, foam sclerotherapy. He is a graduate of Guy’s Hospital Medical School and a fellow of Royal College of Surgeons of England.