Sclerotherapy is inherently a safe treatment. However, as with all forms of invasive treatment, adverse reactions can occur: •Local oSkin pigmentation - Skin hyperpigmentation overlying the treated varicose veins and spider veins is a common occurrence and probably effects one in five clients treated with foam sclerotherapy. - Spontaneous resolution occurs with 6-12 months of treatment in >75% of cases. However, a very small proportion of clients will be left with an element of permanent skin hyperpigmentation that although not clinically significant, may be cosmetically apparent. oTelangiectasia - Although foam sclerotherapy is often employed to treat telangiectasia, new telangiectasia may form following foam sclerotherapy. - Clients may notice fine purple veins forming at the site of treatment. - These can be successfully treated with further sclerotherapy or with other techniques in the majority of cases. oSuperficial thrombophlebitis - A common side effect of sclerotherapy due to its underlying mechanism of action is the painful build up retained clot in the varicose vein itself. - This is not a DVT and is rarely dangerous. - Clients may notice a hard, painful, lumpy area at the site of treatment of the larger veins or ongoing discomfort at the site of spider/reticualr vein treatment. - This will often respond to topical NSAIDs e.g. ibuprofen cream. In addition your surgeon may elect to aspirate the clot through a small needle providing pain relief when larger veins are invovled. oRecurrence or residual veins - One in three or four clients will require a further treatment session to treat residual veins following the first treatment - One in three clients will develop a recurrence of or new varicose veins within three years of the initial treatment. oUlceration - Very occasionally the sclerosant can seep out of the treated vein into the surrounding tissue or adjacent micro-arteries (arterioles) causing inflammation, necrosis and skin ulceration. The majority will spontaneously heal albeit with a small scar, but on occasion the ulcer will require further treatment to attain healing. •Systemic oCardiorespiratory - Occasionally during the treatment itself clients may experience chest tightness, a bout of coughing or light headiness. - We do not perform foam sclerotherapy in clients with asthma or a known patent foramen ovale oNeurological: - Transient post-procedural migraine or visual disturbances are reported in ≈1% of clients; the majority occurring within one hour of the procedure. These spontaneously resolve and appear to cause no permanent sequelae. - Mini Stroke: There have been reports in the medical literature of transient ischaemic attack occurring following foam sclerotherapy. This would appear to very rare and spontaneously fully resolve within 30 mins of occurrence. oDeep Vein thrombosis (DVT) - DVT may occur after foam sclerotherapy but is also very rare and appears to be no different in risk to other minimally invasive techniques for treating varicose veins e.g. radiofrequency ablation. oUlceration - Very occasionally the sclerosant can seep out of the treated vein into the surrounding tissue or adjacent micro-arteries (arterioles) causing inflammation, necrosis and skin ulceration. The majority will spontaneously heal albeit with a small scar, but on occasion the ulcer will require further treatment to attain healing. oAnaphylaxis/severe allergy - Just as with exposure to any medical drug for the first time, it is possible to have a very severe allergic reaction to the foam sclerosant. This is thought to affect 1 in 10,000 people. The vast majority of patients undergoing sclerotherapy do not suffer any significant complications and are satisfied with their clinical outcome.