Allergic Angioedema: This is the most common cause of angioedema, often triggered by an allergic reaction to foods, medications (especially ACE inhibitors), or insect bites. It presents with rapid swelling of the skin and mucous membranes, which can be life-threatening if it involves the airway.

Hereditary Angioedema (HAE): A genetic disorder characterized by recurrent episodes of severe angioedema, often without urticaria. It is caused by a deficiency or dysfunction of C1 esterase inhibitor.
Idiopathic Angioedema: Angioedema without an identifiable cause, which can be frustrating to diagnose and manage.
Drug-Induced Angioedema: Certain medications, such as ACE inhibitors, NSAIDs, and some antibiotics, can cause angioedema as a side effect.

Anaphylaxis: A severe, life-threatening allergic reaction that can present with angioedema, among other symptoms like hypotension, respiratory distress, and cardiac issues. Prompt recognition and treatment with epinephrine are crucial.
Airway Obstruction: Any cause of angioedema that compromises the airway can be fatal if not immediately addressed. This includes swelling of the tongue, throat, or larynx.
Insect Bite or Sting Allergy: Certain insect bites or stings can trigger an allergic reaction leading to angioedema, which can be severe and potentially life-threatening.

Acquired Angioedema: Associated with conditions like lymphoproliferative disorders, autoimmune diseases, or the use of certain medications, which can lead to the consumption or inhibition of C1 esterase inhibitor.
Angioedema due to Complement Disorders: Disorders affecting the complement system can lead to angioedema, often as part of a broader syndrome.
Gleich's Syndrome (Eosinophilic Angioedema): A rare condition characterized by episodic angioedema associated with significant eosinophilia, often without an identifiable cause.