What Causes Spider Veins?

What Causes Spider Veins?

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Spider veins or thread veins are the superficial leg veins that are visible just beneath the skin’s surface on areas such as the thighs, ankles, calves, chest, hands, or face. They appear in various colors, such as blue, red, and purple. These clusters of thin vessels branch out into a spider web-like shape and are associated with weakened, damaged veins. This is an extremely common issue, and the veins aren’t typically harmful to a person’s health. However, patients often do choose to have them treated because they are self-conscious about the discolorations. Sclerotherapy, which our Chesterfield-based West County Dermatology team offers, is one of the most frequently used methods for treating spider veins. Our team considers this to be the most beneficial treatment for a number of reasons.

How Spider Veins Form

But first things first: What are the actual underlying causes of this problem? The exact reason why some patients get these twisty, visible veins while others do not isn’t clear. Your veins are designed to carry blood around the body, including back to the heart from various extremities. Spider veins typically occur when valves in the veins aren’t functioning properly and the blood flows backward, accumulating inside the dilated, “dead end” veins. The walls of the veins weaken, so they become enlarged—and thereby more visible through the skin.

In some cases, spider veins form when tiny blood vessels burst due to excess pressure or sun damage. They are much more common among women than men, though anyone can get them. Many people who develop spider veins have a genetic factor. Some of the other risk factors include having a job that causes you to have to sit or stand for long periods of time, aging, pregnancy, being overweight or obese, natural hormonal changes, and using hormonal birth control or other types of hormone therapy.


Sclerotherapy is the go-to treatment for spider veins. During a session, we inject a concentrated irritating solution directly into the unwanted vessels. The walls of the blood vessels essentially collapse. Then the veins break down and fade away within a few weeks.

Interested in learning more about sclerotherapy and other treatments? Get in touch with our team at West County Dermatology by calling us at 636.532.2422, or submit a contact form to request a consultation.