angioedema, is allergen the most common cause

Introduction and Symptoms

Angioedema is the clinical manifestation of transient swelling of the subcutaneous layer of the skin involving lip, eyes and face.  However, angioedema may spread to other parts of the body like respiratory, laryngeal and gastrointestinal (GI) mucosa which can be life-threatening.  Additional symptoms of  may include stomach cramping and hot or painful sensation in the swollen areas.

Risk factors or causes

This can be classified as allergic, hereditary or idiopathic. Mechanism of any allergic reaction is release of histamine from mast cells and hence allergic angioedema responds to antihistamines. While hereditary angioedema is due to deficiency of C1 esterase and bradykinin mediated reactions that do not respond to antihistamines. Exact cause of idiopathic angioedema is not known, but it responds to antihistamines.


Management of symptoms   depends upon its severity and nature. In emergency situation , primarily patency of airway is maintained. Priority is to maintain the breathing, in some life threatening situations, even tracheostomy,   cricothyrotomy, direct laryngoscopy  and fiberoptic intubation is performed. 

Avoidance and removal of the triggering agent or allergen as far as possible is the first line of treatment in case of allergic angioedema. Adrenaline or epinephrine is injected intramuscularly to reduce swelling of larynx and airways. Antihistamines and corticosteroids is the second main stay of treatment (after adrenaline) due to their slow onset of action. Symptoms  can also arise due to ACE inhibitors, in that case they should be stopped immediately and treatment plan with antihistamines and corticosteroids should be started.

Hereditary angioedema is due to impaired metabolism of bradykinin. Hence, it cannot be cured with the help of adrenaline, antihistamines or steroids.  In that case a preventative approach is always preferred.  Prophylactic treatment includes tranexamic acid and modified androgens like danzolol or stanozolol. In case of severe and frequent episodes of hereditary angioedema, C1 inhibitor replacement therapy is the first line of therapy.  Kallikrein inhibitor  antagonist like ecallantide and selective bradykinin B2 receptor are also used for severe episodes

Self care

People having frequent symptoms should make a note of which allergen triggers their symptoms and should avoid it completely.  Any over the counter medicines, herbs or   supplements should be avoided. Cool shower or application of cold compress on the affected area can provide pain relief.  The affected area should never be rubbed or scratched and an OTC antihistaminic can prove as an effective treatment.  The loose fitted cotton cloth should be worn to   avoid further irritation.

  If only swelling is present and there is no respiratory or gastrointestinal symptoms, there is no need to panic, it gets resolved within 48 -72 hours. But breathing difficulties or abdominal cramps should not be taken lightly and immediately hospital casualty should be addressed. It is always advisable to carry a management card that briefly explains the diagnosis, the best treatment for acute attacks, and provides contact information of the concerned specialist

Drugs used in treating

Drugs used in treatment of allergic variant include adrenaline, antihistamines and corticosteroids.  While hereditary type is treated with C1 esterase replacement therapy, plasma kallikrein inhibitor and specific inhibitor to the bradykinin B2 receptor. Prophylactic treatment is done with  tranexamic acid and modified androgens.

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