Local Anesthetics - Toxicity

Allergic reactions

Allergic reactions

1. True allergic reactions to local anesthetics are rare. Vasovagal episodes and responses to intravascular injection of local anesthetic/epinephrine are more common.
2. Ester-type local anesthetics may cause allergic reactions from the metabolite PABA. Patients allergic to PABA should avoid methylparaben owing to the structural similarity.
3. Amide-type local anesthetics are nearly devoid of allergic potential.
4. Epinephrine containing solutions with sulfa-antioxidants may cause allergic reactions in patients with sulfa allergies.
5. Local hypersensitivity reactions may produce local erythema, urticaria, edema, or dermatitis.
6. Systemic hypersensitivity reactions are rare and can present with generalized erythema, urticaria, edema, bronchoconstriction, hypotension, and cardiovascular collapse.
7. Treatment is supportive.