Anaphylaxis

Anaphylaxis is a severe allergic reaction that can be life-threatening, characterized by the sudden onset of symptoms involving the skin, respiratory tract, gastrointestinal system, and cardiovascular system, caused by chemical mediators released from mast cells or basophils.

Early symptoms of anaphylaxis can vary depending on the trigger, but they typically occur within a few minutes to two hours after exposure.

Initially, patients may feel tingling around the mouth or face, followed by warmth, difficulty swallowing, and a sensation of tightness in the throat or chest. Sweating with itching, anxiety, and weakness may occur, along with flushing, urticaria, and angioedema. Voice changes, inspiratory stridor, dysphagia, nasal congestion, periorbital itching, sneezing, and wheezing can also appear. Gastrointestinal symptoms such as abdominal pain, diarrhea, and uterine cramps or bleeding may occur, along with dizziness, hypotension, tachycardia, arrhythmia, and impaired consciousness.

The earlier the symptoms appear after exposure, the more severe the reaction tends to be. Since delayed biphasic reactions may also occur, patients should be monitored even after initial symptom resolution. Notably, about 20% of patients may experience anaphylaxis without any skin manifestations, so in cases previously diagnosed as asthma with severe airway constriction, anaphylaxis should be considered as a differential diagnosis.

1. Food (most common)

- The most common causative allergens in Korean children: Cow’s milk > egg > walnut 

-  In children under 6 years of age, milk and egg are the most frequent triggers, whereas in those aged 6–18 years, seafood and buckwheat are more common

2. Drugs

- Drug-induced anaphylaxis becomes more common with increasing age. 

- In children of school age and younger, antibiotics are the primary cause, while in older children and adolescents, both antibiotics and non-steroidal anti-inflammatory drugs (NSAIDs) are major triggers. 

- Vaccines, immunotherapy, and radiocontrast agents

3. Insect Venom

Most patients who experience anaphylaxis due to insect allergy had no significant reaction to previous stings. 

4. Exercise

- Exercise-induced anaphylaxis: A rare form of physical allergy that typically begins within 10 minutes (up to 20 minutes) after exercise, with large urticarial lesions that gradually merge and spread across the body. 

- Food-dependent exercise-induced anaphylaxis: When specific food ingestion followed by exercise triggers the reaction, whereas the food or exercise alone does not. 

5> Idiopathic

- Without an identifiable trigger