Spider veins may be unsightly, but pose no medical threat

Q: I have developed many small, thin veins on my legs. I would like to get rid of them. What is the most effective treatment?

A: Superficial leg veins, sometimes called "spider veins," occur when tiny veins appear just below the surface of the skin, causing red, blue or purple discolorations.

Spider veins get their name from the shape of the discolorations. Some cases of spider veins can be quite small; others are more noticeable.

They may make you feel self-conscious, but they are harmless. (I've put an illustration of spider veins on my website, AskDoctorK.com.)

Spider veins are a sign that there are abnormalities in the deeper veins of the legs. Those deep veins have little valves in them. Blood in the veins of the legs is returning from the legs to the heart. When we are sitting or standing, gravity is pulling the blood downward, away from the heart. The valves prevent gravity from doing that.

As we get older, the valves become less effective. The extra blood that gravity pulls down into the leg veins causes the pressure in the veins to rise.

Ultimately, that increased pressure swells the tiny veins beneath the skin - leading to spider veins.

Spider veins are most common on the thighs, ankles and calves. They are more common in women than men, and they can run in families.

Some cases are related to pregnancy, use of birth control pills or weight gain. Spider veins may be permanent, or they may disappear on their own, especially if they are caused by pregnancy or certain medications.

Spider veins do not require treatment for any medical reason. Treatment is usually done for cosmetic reasons only.

In some people, support stockings may decrease the size of existing spider veins and help to prevent new ones. If that doesn't do the trick, the two most common cosmetic treatments for spider veins are sclerotherapy and laser treatment:

• Sclerotherapy involves having a salt solution injected directly into the affected area. This liquid causes irritation and inflammation of the vein, leading to its collapse. The area may be tender for a few days. Any bruising should fade over a few weeks. Sclerotherapy may require multiple treatments. The injections can be slightly painful.

• Laser treatment directs pulses from a laser light to the spider veins, causing tiny blood clots to form. The blood vessels that form the legs of the "spider" become blocked off and are reabsorbed by the body.

Each treatment has its pros and cons.

Sclerotherapy is better for larger veins, but it involves needles and injections.

Laser therapy can be as effective for smaller veins, but it may result in loss of skin pigment.

In studies comparing the treatments, sclerotherapy is more likely to be successful.

Maintaining a healthy weight and staying physically fit tend to reduce the pressure inside leg veins. Wearing support hose can further protect against the development of more spider veins.

To get rid of the ones you have, talk to your doctor about the alternatives I've described.

• Dr. Komaroff is a physician and professor at Harvard Medical School. For questions, go to AskDoctorK.com.