What Causes Spider Veins?
Medically verified
Last updated on 1/29/2026

By Dr. Michael Nguyen
Vein Doctor at Vein Treatment Clinic
Harvard Medical School
Board Certified by the American Board of Venous and Lymphatic Medicine
Spider veins develop when small surface veins widen and become visible through the skin. Many patients notice them gradually and wonder why they formed in the first place.
In most cases, spider veins are not caused by a single factor. They usually develop due to a combination of genetics, hormonal influences, and pressure within the vein system.

Understanding what causes spider veins helps patients recognize risk factors, set realistic expectations, and decide when evaluation or treatment may be helpful.
If you’re unsure which factors may be contributing to your spider veins, a vein evaluation can help clarify the cause.
Genetics and family history
Genetics play a major role in spider vein development. People with family members who have spider veins are more likely to develop them.
Inherited differences in vein structure and valve strength increase susceptibility over time.

Spider Vein before and after treatment pictures.
Results may vary according to each case.

Spider Vein before and after treatment pictures.
Results may vary according to each case.
Hormonal changes
Hormonal fluctuations can weaken vein walls and contribute to spider vein formation.
This is why spider veins are more common during pregnancy, with birth control use, or during menopause.
Pregnancy-related vein pressure
Pregnancy increases blood volume and pressure in the leg veins while hormones relax vein walls.
Spider veins may improve after pregnancy, but underlying vein changes can persist.
Symptom Checker
Prolonged standing or sitting
Long periods of standing or sitting reduce the muscle action that helps move blood out of the legs.
Over time, increased vein pressure can cause small surface veins to dilate and become visible.
Sun exposure
Sun exposure can damage small blood vessels near the skin, particularly on the face.
This damage makes spider veins more likely to appear in sun-exposed areas.
Aging and vein elasticity
As people age, veins naturally lose elasticity and strength.
Weaker vein walls are more likely to stretch and show through the skin.
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Underlying vein pressure or reflux
In some cases, spider veins are linked to increased pressure from deeper vein reflux.
When underlying reflux is present, spider veins may recur unless the deeper issue is addressed.
Get the Facts on Chronic Venous Insufficiency. Read the Complete Guide
Do lifestyle factors cause spider veins?
Lifestyle factors such as inactivity, prolonged immobility, and excess weight can increase vein pressure.
While these factors may contribute, they are usually part of a broader set of causes rather than the sole reason spider veins form.
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About the Medical Team at Vein Treatment Clinic
Vein Treatment Clinic is powered by VIP Medical Group and built around a single guiding principle: deliver the highest standard of vein care using an academic, evidence-based approach combined with the most advanced, minimally invasive technology available today.
Clinical leadership at Vein Treatment Clinic is guided by board-certified vein specialists, including Dr. Michael Nguyen, whose training and experience help shape the clinic’s rigorous standards of care.
All physicians at Vein Treatment Clinic follow a structured, highly standardized clinical model. This includes ongoing training in the latest non-surgical vein treatments, continuous review of emerging research, and strict adherence to proven safety and quality protocols.
Patients benefit from a team-based model of care where expertise is shared, best practices are consistently applied, and treatment recommendations are driven by data, experience, and long-term results.

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At Vein Treatment Clinic, education is considered a core part of treatment. Patients are encouraged to understand their condition, their options, and the reasoning behind each recommendation, so they can move forward with clarity and confidence.
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