Why Do I Have Varicose Veins? Causes and Risk Factors Explained

People tend to blame themselves for varicose veins. They assume it was their job that kept them standing or sitting for hours at a time, the weight they meant to lose, or the years they skipped the gym. Patients often lead with an apology before describing leg symptoms, even to their closest friends or trusted vein physician.

But the real answer is less personal, and more systemic: varicose veins are a mechanical failure inside the vein, and the strongest predictor of who gets them is family history. Most of what raises your risk was decided before you had any say.

And they are also extremely common. The American Heart Association reports that among adults aged 40 to 80, an estimated 33 million Americans have varicose veins, and roughly two out of every three are women. About 2 million of that group go on to develop chronic venous insufficiency, which is the stage where symptoms such as skin damage and leg ulcers can appear.

What Causes Varicose Veins Is a Valve, not a Habit

Blood gets down to your feet the easy way. Gravity does the work. Coming back up is the hard part, because by the time blood reaches your ankles, most of the push from your heart is spent. Your legs must handle the return trip themselves. Your calf muscles squeeze with every step, pushing blood upward. Behind each push, small one-way valves snap shut so nothing slides back down.

When a valve fails to close properly, blood flows backward and pools below it. Johns Hopkins Medicine describes the result as increased blood pressure in the veins nearest the skin surface. That pressure stretches the vein wall, pulling the next valve down the line out of alignment, so it starts leaking too.

This is why varicose veins tend to appear gradually and then seem to arrive all at once. The process builds quietly for years before anything shows through the skin.

It also explains why the answer to what causes varicose veins is never a single event. Usually, no single moment causes a vein to go wrong. Instead, the plumbing gradually declines, and the result becomes visible only when it crosses a threshold.

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Risk Factors for Varicose Veins You Cannot Change

The Mayo Clinic identifies family history and obesity as the two main risk factors for varicose veins, and adds aging, being female, pregnancy, and long stretches of standing or sitting. Most of that list is outside anyone’s control.

• Family history. If your parents had varicose veins, your odds go up. This is the factor that explains why two people with identical jobs and habits end up in different places.
• Age. Vein valves wear out with use, the same way other tissue does. Decades of standing upright is a lot of work for a one-way valve the size of a grain of rice.
• Being female. Hormone shifts before a period and during pregnancy or menopause can relax vein walls. Hormone treatments, including birth control pills, may raise risk as well.
• Pregnancy. Blood volume increases to support the pregnancy, and the growing uterus adds pressure on the veins in the pelvis. Veins that surface during pregnancy sometimes fade afterward and sometimes stay.
• A previous leg injury or blood clot. NYU Langone Health lists a past blood clot in the leg and prior leg injury, even one as minor as hitting your leg on a table, among varicose vein risk factors.

Risk Factors You Can Control

A shorter list: none of these controllable risk factors prevent varicose veins outright, and none of them undo a valve that has already failed. They influence how much pressure your veins work against day to day, which affects how you feel and possibly how fast things change.

• Long periods of standing or sitting. Blood pools when you hold one position; moving every hour helps more than any single change.
• Inactivity. Walking engages the calf muscles that pump blood up your legs.
• Body weight. Extra weight increases the pressure inside leg veins.
• Smoking. Tobacco use adds to the pressure your leg veins already work against and damages blood vessels everywhere in the body.

What Does Not Cause Varicose Veins

Crossing your legs gets blamed most often. So do high heels, sitting on hard surfaces, and cold feet. None of these show up on the risk factor lists that vein specialists actually use.

A pattern emerges in what does and does not matter, and it is worth knowing. Real risk factors are the ones that keep pressure on your veins for years at a time: your genetics, your age, pregnancy, a job that keeps you upright for eight hours. Momentary positions do not make the list. Crossing your legs for twenty minutes does not damage a valve.

TIP: Vein advice spreads fast on social media, and the posts that travel furthest tend to name a single simple habit. When one of these “too easy to be true” hits your feed, ask yourself this: does the claim describe something happening over years, or something happening over minutes? Years means it's worth considering. Minutes means scroll on.

Why the Cause Matters More Than the Cosmetics

Understanding what causes varicose veins also explains why treating the visible vein alone falls short. The leak causing the problem often sits deeper in the leg than what you can see. CVR vein experts use duplex ultrasound to trace blood flow and identify which valves are failing, then treat the source with minimally invasive, office-based procedures. If your leg symptoms come from something other than your veins, you'll be referred to the right specialist.

Remember, waiting has a cost. Varicose veins tend to get worse over time. Complications of untreated varicose veins include worsening leg pain, swelling, skin discoloration, and venous leg ulcers.

Frequently Asked Questions

Q: Are varicose veins hereditary?
A: Family history is among the strongest risk factors. The Mayo Clinic names it one of the two main risk factors, alongside obesity. Having a parent with varicose veins does not guarantee you will get them, but it raises the odds considerably.

Q: Does standing all day cause varicose veins?
A: Standing for long stretches is a recognized risk factor, but it is not a cause on its own. Two people with the same job can end up with very different legs, and family history usually explains the difference. Moving regularly matters more than the total hours on your feet.

Q: Can pregnancy cause varicose veins permanently?
A: Pregnancy raises blood volume and adds pressure on the veins in the pelvis, which can bring varicose veins out. Some fade in the months after delivery. Others stay, and veins that persist beyond a few months after birth are worth having evaluated.

Q: Do men get varicose veins?
A: Yes. Being female raises risk, but men develop varicose veins too, and they are often diagnosed later because the symptoms get attributed to age or activity instead. Aching, heaviness, and swelling deserve the same attention regardless of who is describing them.

Q: Can I prevent varicose veins if they run in my family?
A: You cannot change the underlying tendency. Staying active, avoiding long stretches in one position, and wearing compression stockings if your doctor recommends them all reduce the pressure your veins work against. Think of it as slowing things down rather than preventing them.