How to differentiate ACE inhibitor-induced angioedema from "allergic reactions": no urticaria or itching with ACEi

Angiotensin-converting enzyme inhibitors (ACE-Is) are associated with angioedema, a potentially life-threatening adverse reaction.

A 5-year medical record review included all patients seen with angioedema at a community hospital ED.

ACE-I-induced angioedema (AIIA) was more likely to be associated with:

- age of 65 years or older
- unilateral symptoms
- absence of urticaria or itching

Community hospital admission rates for AIIA were 14%- significantly lower than those from a tertiary care study (41%). Lack of urticaria or itching may help differentiate AIIA from allergic reactions.

Angioedema (AE) can be allergic or non-allergic.

There are 5 types of non-allergic angioedema (AE):

- acquired AE
- hereditary AE (HAE)
- ACE-inhibitor induced AE
- idiopathic AE, can occur with chronic urticaria
- pseudoallergic AE, e.g. reaction to NSAIDs

There are 3 types of HAE that are differentiated by C4 and C1-INH levels

- type I HAE - low C4, low C1-INH function, low C1-INH antigen level
- type II HAE - low C4, low C1-INH function, normal C1-INH antigen level
- type III HAE - all normal

References:

Angiotensin-converting enzyme inhibitor-induced angioedema in a community hospital emergency department. Bluestein, Hazel M.; Hoover, Todd A.; Banerji, Aleena S.; Camargo, Carlos A.; Reshef, Avner; Herscu, Paul. Annals of Allergy, Asthma and Immunology, Volume 103, Number 6, December 2009 , pp. 502-507(6).
Angioedema Due to Angiotensin Converting Enzyme Inhibitors
Abdominal angioedema secondary to acquired C1 esterase functional deficiency
Hereditary Angioedema (HAE) in a Teenager: Diagnosis and Treatment

The first ACE inhibitor (captopril) was developed from viper venom by a Brazilian post-doc. The FASEB Journal, 2003;17:788-789.
Angioedema due to the renin inhibitor aliskiren. CCJM, 2011.

The photographed patient gave a permission for her photograph be taken and used for medical education.