Anaphylaxis caused by benzalkonium in a nebulizer solution

Benzalkonium chloride (BAC) is commonly used as a bactericidal preservative in nebulizer solutions, and can cause paradoxical onchoconstriction following nebulizing therapy in some asthmatics. We describe a case of anaphylactic shock in a 23-yr-old asthmatic woman following an intradermal skin test with a salbutamol solution containing BAC. Since she complained of cough and dyspnea after inhalation therapy with a nebulizer solution, we conducted an intradermal skin test using the same solution, which contained BAC. About 10 min later, the patient reported dizziness, palpitations, and dyspnea. On examination, tachycardia, tachypnea, and hypotension were found. She was resuscitated with a subcutaneous injection of epinephrine and an infusion of saline. One month later, we conducted a bronchial provocation test with BAC, and she showed a positive response.