• Tissue irritation caused by local anaesthetics is generally related to the acidity of the infiltrated solution and there are ways to minimise this discomfort, which will be discussed later.

• Ecchymoses or haematomas are a result of the perforation of cutaneous or subcutaneous blood vessels. This may be more severe in patients with a bleeding disorder (inherent or acquired as a result of medications: aspirin, clopidogrel or other anticoagulants). If bruising occurs, the patient can simply be reassured. A significant haematoma may require drainage and a pressure dressing, but this is an extremely rare complication.

• EMLA and other topical anaesthetics can cause itching, burning, pain, pallor, erythema, oedema, and purpura. Irritant dermatitis, allergic contact dermatitis, and contact urticaria can also occur.

• Nerve injury may occur during the infiltration of a local anaesthetic. This may occur from nerve laceration by the needle or nerve contusion by intraneural injection. This complication occurs more commonly during the performance of regional blocks than local infiltration. Clinical indications of potential nerve injury include paraesthesias, ‘electric shock’ sensations and excessive pain during needle insertion, advancement or injection. Withdraw the needle and reposition it should this happen. The majority of neurapraxias resolve over a period of a few days or weeks.

• Nerve injury might also result from an excessively high concentration of local anaesthetic. For this reason, lower concentrations are preferred (bupivacaine 0.5% or lower, ropivacaine 0.5% or lower, lidocaine 2% or lower).

• Acute myotoxicity may be associated with local anaesthetics, but has only been reported following continuous peripheral nerve blocks.

• Infection is a potential complication of any injection. It occurs most commonly as a complication of haematoma formation. Maintain sterile conditions as much as possible, and ensure appropriate treatment of haematomas. Many studies have shown that these procedures are not truly sterile, but need to be as clean as possible. Extra care must be taken with patients who are immunocompromised.