Diagnosis and treatment of complications associated with local anaesthesia.

The safety record of local anaesthetic agents is high but complications do occur. These may be systemic reactions to the local anaesthetic itself or to the vasoconstrictor. The former may be allergic or toxic in nature. Psychomotor reactions, often attributed erroneously to the vasoconstrictor, are more common. Regional complications, usually due to faulty technique, may be immediate or delayed. Among the former are pain, haematoma formation, tissue blanching, facial paralysis, amaurosis, diplopia and needle breakage. The delayed regional complications include pain, prolonged anaesthesia or paraesthesia, trismus, infection, sloughing and ulceration. The management of these complications is described.