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.

(see prescribing information for more details)