What is anaphylaxis?

Anaphylaxis is a sudden, severe, potentially fatal, systemic allergic reaction that can involve various areas of the body (such as the skin, respiratory tract, gastrointestinal tract, and cardiovascular system). Symptoms occur within minutes to two hours after contact with the allergy-causing substance but, in rare instances, may occur up to four hours later. Anaphylactic reactions can be mild to life threatening. The annual incidence of anaphylactic reactions is about 30 per 100,000 persons, and individuals with asthma, eczema, or hay fever are at greater relative risk of experiencing anaphylaxis.

What are the common causes of anaphylaxis?

Common causes of anaphylaxis include:

Food

Medication

Insect stings

Latex

Less common causes include:

Food-Dependent Exercise-Induced Anaphylaxis

Idiopathic Anaphylaxis

Who is at risk for having an anaphylactic reaction?
Anyone with a previous history of anaphylactic reactions is at risk for another severe reaction. Individuals with food allergies (particularly allergies to shellfish, peanuts, and tree nuts) and asthma may be at increased risk for having a life-threatening anaphylactic reaction. A recent study showed that teens with food allergy and asthma appear to be at highest risk for a reaction because they are more likely to dine away from home, they are less likely to carry medications, and they may ignore or not recognize symptoms.

What are the symptoms of an anaphylactic reaction?
An anaphylactic reaction may begin with a tingling sensation, itching, or metallic taste in the mouth. Other symptoms can include hives, a sensation of warmth, asthma symptoms, swelling of the mouth and throat area, difficulty breathing, vomiting, diarrhea, cramping, a drop in blood pressure, and loss of consciousness. These symptoms may begin in as little as five to 15 minutes to up to two hours after exposure to the allergen, but life-threatening reactions may progress over hours.

Some individuals have a reaction, and the symptoms go away only to return two to three hours later. This is called a “biphasic reaction.” Often the symptoms occur in the respiratory tract and take the individual by surprise.