Standard Sclerotherapy: Possible side effect following treatment of spider / superficial veins

Even when a highly experienced physician is performing the treatment, there are a number of possible side effects that are listed below. If you have had previous episodes of deep clots (thrombosis) in your leg this may mean that you are unsuitable for treatment. Our doctors will discuss this with you. There is some suggestion that the taking of the oral contraceptive pill and hormone replacement therapy (for menopause symptoms) during treatment increases the risk of a Deep Vein Thrombosis however the evidence is weak and is probably not a reason to stop taking these medications during treatment. Similarly, people who smoke have a slight increase in risk.


This is the appearance of brown marks on the skin after treatment along the line of a treated vein. Some studies show an incidence as high as 16% at 6 months and 5% at 2 years. These pigmented areas are mainly composed of haemosiderin (a form of iron stored in the blood) and are the result of the blood being broken down in a vein after treatment. It is more likely to occur in patients who have larger veins treated or those patients who have a lot of bruising. In most cases, pigmentation disappears completely within a year. Persistent pigmentation may respond to laser treatment.


This is the development of networks of fine red blood vessels near the sites of injection of larger vessels, especially on the thighs. Most resolve spontaneously, some resolve with injection treatment, and a few persist. Matting is more common in patients with extensive surface veins, deep vein problems, patients who have a family history of surface veins, obese patients who have poor muscle tone and those patients who have not had reticular veins treated before spider veins.


Very occasionally there is the formation of small, painful ulcers at a treatment site within 2 weeks of injection. These may occur because the solution has escaped into the surrounding skin or sometimes because there is an abnormal connection between the small veins that are injected and the nearby arteries. Ulcers are more common in patients who smoke cigarettes. They heal slowly and may leave a small pale scar.


Although on rare occasions (1 per 5,000) such reactions may be serious. They can usually be very effectively treated by the immediate injection of adrenaline. Less serious reactions are treated with antihistamines. Minor rashes require no specific treatment but you should inform the doctor if they occur. Rarely, inflammation of the gums (gingivitis) appears as a reaction to a specific sclerosing solution. If this occurs, a different solution can be used for subsequent treatments.


This can occur but is uncommon if compression and regular daily walking are adhered to.


This is an extremely uncommon complication, which may result in muscle and skin damage.

There are no known long term side effects of sclerotherapy.


See more commonly asked questions in our FAQ's section about varicose and spider veins.