Based on the Naranjo Adverse Reaction Scale, the angioedema episodes from haloperidol and iloperidone scored 5 and 7 respectively, indicating probable associations between these medications and this reaction.11 Angioedema can be classified as hereditary, acquired, allergic, secondary, or idiopathic. The mechanism for angioedema in our patient is unclear, but likely allergic in nature since he quickly responded to corticosteroids and diphenhydramine. The patient does not have a family history of angioedema and complement factor was not measured. Similar to other cases of antipsychotic-induced angioedema, likely from an allergic reaction, also responded to medication discontinuation and antihistamine and steroid treatment.2, 6, 7, 9
This letter not only reports the first cases of angioedema with iloperidone and haloperidol but also highlights the risk of cross-sensitivity between these different chemical classes of antipsychotics.