Serious complications after foam injections have been reported in some patients. Complications of foam sclerotherapy include inflammation of veins, deep vein thrombosis and pulmonary embolism (blocakage of lung artery) and changes in the skin's colouring. About 2% of patients have short-term side effects, including chest tightness, dry cough, headache, 'pins and needles' or problems with their vision.
One study reported on 3 patients who had strokes after the procedure. All had a kind of heart defect called a patent foramen ovale. All 3 patients recovered completely and had no further symptoms of stroke. In a study of 1025 patients treated with foam injections,1 patient had a type of ‘mini-stroke’ called a transient ischaemic attack. This patient recovered in half an hour.
In a report on about 6400 foam sclerotherapy sessions, there were 37 adverse events (less than 1%). These included brief problems with vision (eight cases), while some people with vision problems also had headache, nausea or fainting (eight cases). In all 16 cases the problems disappeared on their own, with no after effects. Six patients fainted, three had thrombosis and one had deep vein thrombosis. One patient had a stroke shortly after having foam sclerotherapy. The risks with foam sclerotherapy and liquid sclerotherapy are about the same.
Darkening of the skin can occur after foam sclerotherapy in about 1 in 4 patients. It may take up to 2 or more years to resolve but can occasionally be permanent.