Adverse Reactions

Provided that Fibrovein is injected correctly at the appropriate concentration then the only likely adverse reactions are pigmentation and thrombophlebitis. For more information, see Summary of Product Characteristics.

Pigmentation is caused by haemosiderin staining of the dermis and looks like bruising over or around the treated blood vessel. The incidence is low and usually resolves over 12-18 months.

Mild thrombophlebitis is not uncommon after sclerotherapy and is due to trapped blood in the vein. It is usually localised and self limiting and easily aspirated at the follow up.

Occasionally people may be allergic to the product and reactions are usually mild but may result in anaphylactic shock.

Necrosis and ulceration should be very rare and are caused by injecting outside the vein or from using too high a concentration.

Information about adverse event reporting in the UK can be found at Adverse events should also be reported to the Pharmacovigilance Department at STD Pharmaceutical Products Ltd.


A complication of sclerotherapy regardless of the sclerosant used is pigmentation over or around the treated blood vessel. Pigmentation is caused by haemosiderin staining of the dermis. The haemosiderin probably comes from red blood cells that extravasate into the dermis as a result of the inflammatory response or ruptured vessels.

The level of pigmentation seems to be dependent on the level of inflammation. Lower concentrations of Fibrovein are effective at sclerosing small veins but cause less inflammation and consequently less pigmentation. It has been shown that use of lower concentrations of STS reduces the level of pigmentation (Tretbar 1989).

Other factors that can influence the level of pigmentation include gravitational pressure. Lower levels of pigmentation are seen if the treatment proceeds in a proximal to distal manner. Injecting the thread veins first can result in more pigmentation due to pressure from the feeder vein causing RBC’s and haemosiderin to extravasate. Applying compression will also help.

Thread veins can be associated with a larger incompetent reticular or varicose vein and will sometimes resolve once the reticular vein has been treated.

Injection pressure is also important since the small vessels have very thin walls, excessive pressure may cause vessel rupture. Some patients are prone to pigmentation others, are not. The reported incidence of hyper-pigmentation varies from 10-30%, it is usually not permanent but may last for up to 18 months. Persistent pigmentation, lasting over 12 months, should be seen in no more than 1-2% of patients (Goldman & Bergen 2001).

Pigmentation can be reduced by following a meticulous technique, avoid excessive injection pressures; ensure that the correct strength of sclerosant is used. Treat areas of reflux in a proximal to distal manner. Apply immediate compression to prevent re-entry of blood into the injected area and maintain for 1-3 weeks. 


It is important to note that the hard sclerothrombus formed at the injection site is part of the process, however ‘soft’ thrombi may result after sclerotherapy due to trapped blood in the remainder of the vein.

Once sclerosed the flow through the vein stops and any trapped blood will form a soft thrombus. Thrombi can be minimised by using the empty vein technique followed by immediate compression, however it is difficult to adequately compress some veins and some blood is frequently trapped.

Treatment is uncomplicated and it is best to drain the blood when the thrombus has liquefied (approx 2 weeks). The clot can be drained at the follow up (2-4 weeks) via a small incision or easily aspirated using a needle and syringe.

Sensitivity and allergies

Allergic reactions are rare, presenting as local or generalised rash, urticaria, nausea or vomiting, asthma, vascular collapse. Anaphylactic shock, which may potentially be fatal, is extremely rare but remains a possibility.

A history of allergy should be taken from all patients prior to treatment. In particular, allergic reactions to previous injections of sodium tetradecyl sulphate should be noted.

A higher incidence of allergic reaction is thought to result from repeated treatment involving sodium tetradecyl sulphate injection and may involve intervals of several years between courses of injections. A patient who was perfectly alright at the last session may display an allergic reaction.

Necrosis and ulceration

Provided that Fibrovein is injected correctly at the appropriate concentration then ulceration should never happen.

Ulceration or necrosis occur when some of the product is injected outside the vein. The tissue cells die leading to a small area of necrosis which may erupt to the surface as a small ulcer.

Necrosis used to be more of a problem many years ago when too high a concentration was being used to treat thread veins. Some people were using 1% and 3% STS which will cause tissue necrosis.

0.1-0.2% Fibrovein is recommended for thread veins and at this concentration it is unlikely to cause necrosis even if injected outside the vein.

Old wives tales

One of the ‘old wives’ tales is that polidocanol is less painful, causes less necrosis and less pigmentation than STS.

This stems from the early days when Fibrovein and other STS based products were only available as 3% solutions. 3% STS is quite powerful and in small veins could cause pain, necrosis and pigmentation.

When people first tried polidocanol they compared 3% POL with 3% STS and concluded POL was a milder sclerosant and caused less side effects.

However since then people have realised that STS is more surface active and you should compare like for like for example 3% POL should be compared to 1-1.5% STS.

Modern studies show that where the two sclerosants are compared on a like for like basis i.e. the POL concentration is 2-3 times that of STS then the there is no difference between them in terms of pain, efficacy and side effects.

(ref. Rao J, Wildmore J & Goldman M. Double-Blind Prospective Comparative Trial between Foamed and Liquid Polidocanol and Sodium Tetradecyl Sulfate in the Treatment of Varicose and Telangiectatic Leg Veins. 2005. Dermatol Surg 31:6: pp 631-35.)

Thus provided the appropriate concentration of STS is used then injection is no more painful than with POL.