Sclerotherapy involves injection of a medication – the sclerosant, into unwanted veins causing them to collapse, scar up and disappear. The commonest medication used is polidocanol (Aethoxysclerol). Sclerotherapy is highly effective for treating spider veins, and may also be used for larger veins such as varicose veins. When treating large varicose veins however, long term results are less reliable and may result in brown staining of the skin over the site of veins persisting for a prolonged period.


A very fine needle is used to inject the sclerosant into the vein to be treated and a cotton ball and paper tape are applied to each treatment area. After injecting all the relevant veins, the leg is wrapped in a compression bandage for 24 hours. Sometimes a compression stocking is also worn for 2-3 weeks if larger veins are being treated. Driving is permitted after treatment and you should remain active and ambulant. Long haul flights ( longer than 5 hours) usually should be avoided for a period after injections but this should be discussed with Dr Chu.


Minor transient pain may occur at time of injection but significant persistent pain is unusual and should be reported to Dr Chu. When large varicose veins are injected, you will get painful, tender lumpy areas of clotted surface veins that may persist for several weeks.

Swelling may occur to some degree in the treated limb for up to 6 weeks due to inflammation triggered by the injections, particularly when big varicose veins are injected. This is controlled by leg elevation and use of compression stockings. Excessive swelling and pain should be reported if you are concerned. Transient cough or chest tightness is uncommon. Fainting or lightheadedness may occur due to reversible drop in blood pressure and heart rate.

Migraines may be triggered in patients prone to them, and rarely visual disturbances and neurological symptoms have been reported.

Allergic reactions usually involve urticarial skin rashes such as hives. Life threatening anaphylactic reactions are extremely rare.

Deep vein thrombosis is extremely unlikely in treatment of spider veins due to the low concentration and dose of the sclerosant used, but sometimes complicate treatment of bigger varicose veins. Injection site skin ulcers are uncommon, usually small and heal with a small scar. Larger ones may need excision or skin grafting.


Following sclerotherapy, some bruising at injection sites, swelling around the ankles and lumpy clotted veins may persist for a few weeks. Overall improvement in appearance will be noticeable after 4-6 weeks especially for spider veins. Recovery is longer after treatment of large varicose veins, and brown pigmentation of skin may persist for a couple of years.


Pregnancy and Breastfeeding

Polidocanol has not been adequately tested during pregnancy and lactation in humans, and should be avoided in these circumstances. If required, the less effective but safe option of hypertonic saline can be used. You should discuss your preference with Dr Chu.

Known Allergy

If you previously have had an allergic reaction from sclerotherapy, you should notify Dr Chu. Deep Vein Thrombosis If you have a current or past history, or strong family history of deep vein thrombosis, sclerotherapy may be contraindicated. This should also be discussed with Dr Chu.