Serious medical complications from sclerotherapy are extremely rare when a qualified practitioner performs the procedure. However risks include: blood clots, skin discoloration (which can take months to one year to fade), severe inflammation, telangiectatic matting (fine reddish blood vessels around the treated area), allergic reactions to the sclerosing solution and scars.

If there is an underlying problem with the venous system, the veins will recur.

Sclerotherapy appears to work well for most patients. It is estimated that as many as 50-70% of injected veins may be eliminated with each injection session. Less than 10% patients who undergo sclerotherapy for varicose veins do not respond to the injections at all. In such cases, patients may be eligible for laser therapy or surgery.

The veins to be treated are marked while the patient is standing. The skin over the spider veins is cleaned with an antiseptic solution. Bright, indirect light and magnification help ensure that the process is completed with maximum precision. Larger veins are usually treated first.

In most cases, a 23% sodium chloride sterile solution mixed with lidocaine (a local anesthetic) and heparin (an anticoagulant) is injected into the blood vessel using a micro-needle. A solution without lidocaine is available for people who are allergic to lidocaine. The solution causes the vein to turn white (blanch), and then gradually disappear. A typical treatment lasts from 30 minutes to one hour.

Approximately one injection is administered for every inch of spider vein - anywhere from 5-40 injections per treatment session. A cotton ball and compression tape is applied to each area of the leg as it is finished.

Patients may feel a small prick when the needle is injected or a mild burning sensation. However, pain is generally minimal.

The number of veins injected in one session is varies depending on the size and location of the veins, as well as the patient's overall medical condition.

Complete correction is not expected on the first treatment. Only about 50-70% of the treated vessels will be permanently gone. Three to four treatments are generally required for optimal results.

In general, spider veins respond to treatment in 3-6 weeks, and larger veins respond in 3-4 months. If the veins respond to the treatment, they will not reappear. However, new veins may appear over time.

Patients may be asked initially to wear compression hosiery to help keep treated veins closed and to reduce bruising.

Following treatment, patients can immediately resume work and all normal activities. However, patients are advised to refrain from vigorous activities for the first 24 hours.