Spider veins, also known as spider telangiectasias, are small superficial blood vessels that commonly occur on the legs and appear red or blue in the skin. The cause of spider veins is not completely known, but female hormones may play a role in their development. Puberty, birth control pills, pregnancy, or hormone replacement therapy may contribute to them, but genetics has been determined to also have a strong influence. The treatment of these veins with an injectable solution is called sclerotherapy. This procedure has been used for spider veins for over 70 years. One of several kinds of solutions called "sclerosing agents" is injected directly into the blood vessel with a very fine needle. The solution irritates the lining of the vessel causing it to swell and stick together. Over a period of weeks, the vessel is resorbed by the body and fades. A single blood vessel may have to be injected more than one time, usually 6 weeks apart, depending on its size. Any number of vessels can be injected in any one-treatment session. Several different injection solutions are available, and the choice of which to use depends on several factors including the size of the vessel. Contrary to popular belief, newer solutions offer painless and more efficacious results. Our dermatologists will determine if you are a candidate for treatment with sclerotherapy and will choose a solution that will be most beneficial for each particular case.