If you’ve noticed bulging, blue-toned veins on your legs, you’re not alone. Varicose veins affect a large share of adults, and most people want to know one thing first: why did this happen to me?
The short answer comes down to blood flow. But several different factors can push your veins toward that outcome, and some matter more than others depending on your age, sex, and daily routine. Here’s what’s actually going on, and what raises your risk.
How Varicose Veins Actually Form
Your leg veins carry blood back up to your heart, working against gravity the entire way. To help with that, your veins contain one-way valves that open to let blood pass and close to stop it from flowing backward.
Varicose veins happen when those valves weaken or stop closing properly. Blood pools instead of moving upward, and the vein stretches to hold the extra volume. Over time, it bulges, twists, and becomes visible under the skin, according to Cleveland Clinic. Many people also feel aching, heaviness, or mild swelling in the legs before the vein ever looks abnormal.
This backward flow is called venous reflux, and it’s the mechanical cause behind nearly every case of varicose veins, per NIH’s National Center for Biotechnology Information.
Varicose veins are also more common than most people assume. Roughly 23% of US adults have visible varicose veins, and once smaller spider and reticular veins are counted too, that figure climbs to 80% of men and 85% of women, according to a review in the American Heart Association’s journal Circulation.
The Main Causes and Risk Factors
Valve failure rarely happens on its own. It’s usually driven by one or more of the following, and most people who develop varicose veins have more than one at play.
Genetics and Family History
If a parent or sibling has varicose veins, your own odds go up. NIH researchers have documented a clear hereditary and racial pattern in who develops them. In one study of surgeons with varicose veins, 17% pointed to family history as a contributing factor, per a cross-sectional study in PMC.
Age
Vein walls and valves naturally lose elasticity over time. The longer your veins have worked against gravity, the more wear they accumulate. That cumulative strain is a major reason varicose veins become steadily more common as people move through their 30s, 40s, and beyond.
Hormones and Pregnancy
Estrogen relaxes vein walls, which is one reason women develop varicose veins more often than men. Pregnancy adds extra strain from higher blood volume and a growing uterus pressing on pelvic veins, both of which push valves toward failure, per Circulation.
Prolonged Standing or Sitting
Staying in one position for hours makes it harder for calf muscles to help pump blood upward. This is a well-documented occupational risk: a 2025 meta-analysis on PMC found the global prevalence of varicose veins among healthcare workers, most of whom spend long shifts on their feet, is 25%, rising to 28% in the Middle East and North Africa.
Sex Differences
Women are affected more than men at every age. Long-term Framingham Heart Study data, cited by NIH, found that over 16 years of follow-up, 30% of women developed varicose veins compared to 23% of men, with the highest rate of new cases among women in their 40s.
Obesity
Extra body weight adds pressure on leg veins. In the surgeon study cited above, 55.6% of participants with obesity had varicose veins, compared to just 7.8% of those at an average weight. That’s one of the widest gaps found for any single risk factor in that research, and it stacks with age and standing time rather than replacing them.
Other Contributing Factors
A few additional factors can stack on top of the ones above. Previous leg injuries or blood clots can damage valves directly. Low physical activity reduces how often calf muscles help push blood upward. And tight clothing around the waist or thighs can restrict blood flow back toward the heart. None of these single-handedly cause varicose veins, but combined with age, genetics, or a standing job, they add measurable strain.
Can Varicose Veins Be Prevented?
You can’t change your genetics, age, or sex. But you can reduce the everyday pressure your veins carry, and small habits add up over years of standing, sitting, and walking.
- Move regularly. Walking activates the calf muscles that help push blood upward.
- Elevate your legs when resting, especially after long stretches of standing.
- Maintain a healthy weight to ease pressure on leg veins.
- Wear compression stockings if your job keeps you on your feet, a step Mayo Clinic recommends for people at higher risk.
- Avoid sitting with your legs crossed for long periods.
If you’re looking for extra support on top of these habits, Real Science Nutrition’s Vari Veins Miracle is formulated to support healthy circulation and vascular function in the legs. It’s not a substitute for medical care, but it can work alongside daily movement and weight management for people dealing with standing jobs, family history, or other risk factors covered above.
When to See a Doctor
Varicose veins are often just a cosmetic concern, but not always. Talk to a healthcare provider if you notice:
- Pain, throbbing, or heaviness that doesn’t ease with rest
- Swelling that doesn’t go down overnight
- Skin discoloration or hardening near the ankle
- A sore or wound that isn’t healing
A provider can also check whether deeper veins are involved, since surface-level varicose veins sometimes point to a larger circulation issue that’s easier to manage the earlier it’s caught. Cleveland Clinic notes that talking with a provider about varicose veins early, even before they become bothersome, can help lower the risk of complications down the road.
To Sum Up
Varicose veins come down to valves that can no longer keep blood moving in one direction. Genetics, age, hormones, prolonged standing, and body weight all shape how much pressure your veins face over a lifetime. You can’t eliminate every risk factor, but staying active, managing your weight, and paying attention to early symptoms can meaningfully lower your odds, and catching changes early keeps more treatment options on the table.