Have you noticed large, twisted, and swollen veins appearing on your legs or other parts of your body? Varicose veins can be painful as well as unsightly, and may throb as well as itch. You don’t have to live with pain and discomfort when you seek treatment for varicose veins in Houston. If you are suffering from venous insufficiency and varicose veins, there are a number of potential causes that could be behind your condition. Age is one of the primary risk factors for varicose veins, as the valves of your veins can weaken or become damaged over time. People who are overweight or obese are also at greater risk for varicose veins, and losing weight may relieve some symptoms of varicose veins. Take a look at this infographic to learn more about the causes of varicose veins, including why pregnant women should be on the lookout for them. Please share with your friends and family.
Quick Answer: Varicose veins are caused by weak or damaged valves inside the leg veins. Healthy valves let blood flow only upward toward the heart. When they stop closing properly, blood leaks back down and pools, stretching the vein until it bulges and twists. Age, family history, female hormones and pregnancy, excess weight, long hours standing or sitting and a previous blood clot all make valve failure more likely. The visible vein is usually the end result of a leak higher up, which is why a duplex ultrasound is the key test.
Meet your vein specialist
Dr. Syed Raza, MD
Vascular & Interventional Radiology · Founder, Premier Vein & Vascular Center
Fellowship-trained interventional radiologist certified by the American Board of Radiology and the Royal College of Radiologists (UK). Former Chief of Interventional Radiology at UTMB Galveston and Memorial Hermann Memorial City, with 15+ years treating varicose veins, venous reflux and peripheral arterial disease.
What Causes Varicose Veins? The Valve Problem Explained
Your leg veins have a hard job. They carry blood from your feet back up to your heart, against gravity, for most of the day. To make that possible, they contain small one-way valves, thin flaps that open as blood moves upward and snap shut to stop it falling back.
Varicose veins begin when those valves stop sealing properly. Each time you stand, some blood slips backward through the faulty valve. Doctors call this backward flow reflux. The extra blood raises the pressure in the vein below the leak, and over months and years the vein wall stretches. As it widens, the valves below are pulled apart too, so the problem tends to travel down the leg and spread into side branches. The result is the bulging, rope-like vein you can see under the skin.
Varicose veins are one visible sign of a broader condition called chronic venous insufficiency, in which the veins can no longer move blood efficiently out of the legs.
The Calf Muscle Pump and Why Movement Matters
Valves are only half of the system. The other half is your calf muscle. When you walk, the calf muscles squeeze the deep veins and push blood upward, a bit like a hand squeezing a tube. Doctors often call the calf the second heart of the leg.
When the calf pump is not used much, for example during long periods of sitting at a desk or standing still at a counter, blood pools in the lower leg and vein pressure stays high for hours. Stiff ankles, arthritis, injuries and inactivity all weaken the pump. Over time that sustained pressure strains the valves and the vein walls, which is why jobs that keep people on their feet without walking are so strongly linked with varicose veins.
The Main Causes and Risk Factors
No single cause explains every case. Most patients we see have several factors working together.
Genetics and family history
Family history is one of the strongest predictors. Some people inherit vein walls that are more stretchy or valves that are weaker from the start. If one or both parents had varicose veins, your chance of developing them is noticeably higher, sometimes starting in your 20s or 30s.
Hormones
Estrogen and progesterone relax the smooth muscle in vein walls. This helps explain why women develop varicose veins more often, and why symptoms can change with periods, pregnancy, hormone therapy or menopause.
Pregnancy
Pregnancy combines several pressures at once: blood volume rises significantly, hormones relax the veins and the growing uterus presses on the large veins in the pelvis. Varicose veins may appear in the legs and sometimes in the vulva. Many improve after delivery, but each pregnancy can leave the valves a little weaker.
Previous deep vein thrombosis
A blood clot in a deep vein can scar the vein and destroy its valves even after the clot clears. This can lead to post-thrombotic syndrome, with swelling, heaviness and secondary varicose veins in the same leg. A previous deep vein thrombosis is important information for your vein specialist.
Occupation and lifestyle
Nurses, teachers, hairdressers, retail staff, chefs, factory workers and office workers who sit for long hours all put sustained pressure on their leg veins. Smoking, inactivity and a low fiber diet that leads to straining can add to the load.
Pelvic vein problems
In some women, varicose veins on the upper inner thigh, buttock or vulva are fed by leaking veins in the pelvis rather than in the leg. This is linked with pelvic congestion syndrome and needs a different treatment plan.
Primary vs. Secondary Varicose Veins
Vein specialists divide varicose veins into two broad groups, because the cause changes the treatment.
| Feature | Primary varicose veins | Secondary varicose veins |
|---|---|---|
| Main cause | Weak valves or vein walls in the superficial veins | Damage from another problem, most often a previous DVT |
| Typical patient | Family history, pregnancies, standing jobs | History of leg clot, leg injury or surgery |
| Deep veins | Usually normal | Often scarred, narrowed or leaking |
| Common symptoms | Bulging veins, aching, heaviness | More swelling, skin changes and sometimes ulcers |
| Usual approach | Close the leaking superficial vein, then treat branches | Careful assessment of deep veins first; compression is central |
Most varicose veins are primary. Secondary varicose veins are less common but tend to cause more symptoms, which is why a detailed ultrasound matters.
What Happens When the Cause Is Left Untreated?
Varicose veins are not dangerous for everyone, and some people live with small ones for decades with few problems. For many others, though, the underlying reflux slowly progresses, because the higher pressure keeps stretching the next valve down the line. Vein specialists describe this as a gradual sequence:
- Spider and reticular veins appear, often with mild aching or tired legs by evening.
- Bulging varicose veins develop and may throb, itch or feel heavy after long periods on your feet.
- Ankle swelling starts to show up as sock marks at the end of the day.
- Skin changes follow, including brown staining, itchy eczema-like patches and hard, tight skin above the ankle.
- Leg ulcers, slow-healing wounds near the inner ankle, can form in the most advanced stage.
Not everyone moves through every step, and the pace varies widely from person to person. The value of knowing the cause is that treatment can be timed before the skin is damaged, when procedures are simpler and recovery is quicker. If you already have swelling or skin changes, that is a sign the pressure problem has been present for some time and deserves a proper assessment.
Common Myths About What Causes Varicose Veins
Patients often ask us whether something they did caused their veins. These are the questions we hear most:
- Crossing your legs: there is no good evidence that crossing your legs causes varicose veins. Sitting still for long periods is the bigger issue.
- Running or exercise: regular exercise strengthens the calf pump and is good for veins. Exercise does not cause varicose veins, though people with existing veins may notice them more after a workout.
- High heels: heels reduce ankle movement and weaken the calf pump a little, but they are not a main cause.
- Tight clothing: very tight waistbands may be uncomfortable, but they are not a proven cause.
- Spider veins turning into varicose veins: spider veins do not grow into varicose veins, though both can share the same underlying reflux.
Can You Prevent Varicose Veins?
You cannot change your genes or your age, but you can reduce the pressure your veins work against and slow the progression of existing veins.
- Walk daily and take short movement breaks every 30 to 60 minutes if you sit or stand for work
- Do ankle pumps and calf raises during long flights, drives or desk days
- Keep a healthy weight to reduce pressure in the abdomen and legs
- Raise your legs above heart level for 15 to 20 minutes at the end of the day
- Wear graduated compression stockings if you stand for long shifts or are pregnant
- Avoid smoking and stay well hydrated
These habits help symptoms and may slow new veins, but they cannot repair a valve that has already failed. Once reflux is established, treating the leaking vein is the only way to remove the source of the pressure.
How We Evaluate the Cause of Your Varicose Veins
At Premier Vein and Vascular Center, the aim is to find where the leak starts, not just to treat the vein you can see.
- Focused history. We ask about symptoms, how long the veins have been present, pregnancies, family history, your job, prior clots and earlier vein treatments.
- Standing examination. We examine your legs upright to see the full pattern of bulging veins, swelling and any skin changes around the ankles.
- Venous duplex ultrasound. A painless venous ultrasound in our accredited vascular lab maps the superficial and deep veins, measures how long blood flows backward and rules out clots.
- A clear plan. We explain which vein is the source, whether the deep veins are healthy, and the treatment options that fit your findings and goals.
Treatment Options That Address the Cause
Because varicose veins are caused by leaking valves, effective treatment closes or removes the faulty vein so blood reroutes through healthy veins. All of the following are done in the office under local anesthesia and most patients walk out the same day.
- Endovenous ablation: a thin catheter seals the leaking main vein from the inside using heat (radiofrequency ablation or laser) or a non-thermal method
- Foam sclerotherapy: a medicated foam closes smaller branch veins under ultrasound guidance
- Ambulatory phlebectomy: large surface veins are removed through tiny nicks in the skin
- Compression stockings: helpful for symptoms and often part of the plan, but they do not fix the valve
For a fuller overview of procedures, visit our varicose vein treatment page.
Seek urgent medical care if you notice:
- Sudden swelling, pain and warmth in one leg, which may be a deep vein thrombosis
- Chest pain, shortness of breath or coughing up blood
- Bleeding from a varicose vein that does not stop with firm pressure and leg elevation
- A hot, red, very tender lump along a varicose vein with fever
When to See a Vein Doctor in Houston
It is worth having your veins checked if they ache, throb or feel heavy, if your ankles swell by evening, if the skin around your ankles is darkening or itching, or if the veins are getting larger. Houston heat and long commutes can make these symptoms more noticeable for many of our patients. A visit to a vein doctor in Houston with an accredited vascular lab lets us identify the true cause in one appointment. Dr. Syed Raza, a fellowship-trained interventional radiologist, has spent more than 15 years diagnosing and treating venous reflux. Most insurance plans, including Medicare, are accepted, and same-week appointments are usually available.
Talk With a Specialist at Premier Vein
Have questions about your symptoms or treatment options? Dr. Syed Raza and the team at Premier Vein & Vascular Center can evaluate your concerns and explain your options clearly. Same-week appointments are usually available, and most insurance plans are accepted.
Frequently Asked Questions
What is the main cause of varicose veins?
The main cause is valve failure in the leg veins. When the one-way valves stop closing properly, blood flows backward and pools, which raises pressure and stretches the vein until it bulges. Genetics, hormones, pregnancy, weight and long periods of standing all make this more likely.
Are varicose veins hereditary?
Yes, family history is one of the strongest risk factors. People with a parent who has varicose veins are more likely to develop them, often at a younger age, because vein wall and valve strength are partly inherited.
Can sitting all day cause varicose veins?
Sitting for long periods does not directly damage valves, but it keeps the calf muscle pump inactive so blood pools in the lower legs. Over time, that sustained pressure can contribute to varicose veins and make existing ones worse.
Do varicose veins come back after treatment?
A vein that has been properly closed or removed does not reopen in most cases. However, new varicose veins can develop over the years because the underlying tendency remains, so follow-up and healthy habits matter.
Can men get varicose veins?
Yes. Women are affected more often, partly due to hormones and pregnancy, but many men develop varicose veins, especially with a family history, standing jobs or a previous leg clot. Men sometimes delay care until symptoms are advanced.
Are varicose veins a sign of a blood clot?
Varicose veins themselves are not a clot, but they raise the risk of superficial clots and are linked with deep vein thrombosis. Sudden pain, swelling and warmth in one leg should be checked urgently with an ultrasound.
Does hot weather make varicose veins worse?
Heat makes veins widen, so many people notice more swelling, heaviness and visible veins in hot weather. Heat does not cause the valve damage itself, but cool showers, leg elevation and compression can ease summer symptoms.
Trusted Health Resources
- Chronic Venous Insufficiency, Society for Vascular Surgery
- Venous Insufficiency, MedlinePlus Medical Encyclopedia (NIH)
- Varicose Veins and Spider Veins, MedlinePlus (NIH)