Local anesthetics (LAs) have been used to provide anesthesia since the discovery of cocaine in 1884 . They may be administered by topical, infiltrative, nerve block, epidural, or spinal routes . Adverse reactions to LAs are not uncommon and most are nonallergic in etiology. However, allergic reactions to LAs can occur, and the evaluation and management of patients with these reactions will be reviewed here. A related topic, anaphylaxis in the setting of anesthesia or surgery, is found separately. (See "Perioperative anaphylaxis: Clinical manifestations, etiology, and diagnosis" and "Perioperative anaphylaxis: Evaluation and prevention of recurrent reactions".)
The use of LAs for infiltrative anesthesia and for topical anesthesia and a general approach to the management of pain and sedation in children are discussed elsewhere. (See "Infiltration of local anesthetics" and "Topical anesthetics in children" and "Procedural sedation in children outside of the operating room".)
TYPES OF ALLERGIC REACTIONS TO LOCAL ANESTHETICS
Two distinct types of allergic reactions to local anesthetics (LAs) have been described:
- Allergic contact dermatitis and delayed swelling at the site of administration: these types of reactions are well established.
- Urticaria and anaphylaxis: these types of reaction are rare and the data implicating LAs are limited to case reports.
Suspected allergic reactions to local anesthetics (LAs) should be referred for evaluation when possible, because most patients can tolerate other LA agents. Simply advising a patient to avoid all LAs is unnecessarily restrictive, and subjects that patient either to the pain of procedures performed without local anesthesia, or to the increased risks of general anesthesia. Patients with delayed cutaneous reactions may be referred to either dermatology or allergy specialists who perform patch testing, and patients with suspected anaphylaxis should be referred to allergy specialists.