Frequently Asked Questions
What is anaphylaxis?
Anaphylaxis is a serious allergic reaction that is rapid in onset and may cause death.
What are the common causes of anaphylaxis?
Common causes of anaphylaxis include:
- Food
- Medication
- Insect stings
- Latex
Food allergy is believed to be the leading cause of anaphylaxis outside the hospital setting, causing an estimated 50,000 emergency department visits each year in the U.S.
Less common causes include:
- Food-dependent exercise-induced anaphylaxis (occurs when a person eats a specific food and exercises within three to four hours after eating)
- Idiopathic anaphylaxis (anaphylaxis with no apparent cause)
More information about these triggers can be found on our Common Causes of Anaphylaxis and Less Common Causes of Anaphylaxis page.
Who is at risk for having an anaphylactic reaction?
Anyone with a previous history of anaphylactic reactions is at risk for having another severe reaction. Also at risk are those with a personal or family history of allergic conditions, such as asthma, eczema, or hayfever.
Individuals who have asthma in addition to food allergies may be at increased risk for having a life-threatening anaphylactic reaction to food.
A recent study showed that teens with food allergy and asthma appear to be at the highest risk for a reaction, because they are more likely to dine away from home, are less likely to carry medications, and may ignore or not recognize symptoms.
How can I determine if I’ve had anaphylaxis?
Anaphylaxis is highly likely to occur when any ONE of the following happens within minutes to hours after ingestion of the food allergen:
1. A person has skin symptoms or swollen lips and either :
- Difficulty breathing, or
- Reduced blood pressure
2. A person was exposed to a suspected allergen, and two or more of the following occur:
- Skin symptoms or swollen lips
- Difficulty breathing
- Reduced blood pressure
- Gastrointestinal symptoms (i.e., vomiting, diarrhea, or cramping)
3. A person was exposed to a known allergen, and experiences:
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What are the symptoms of an anaphylactic reaction?
An anaphylactic reaction may begin with a tingling sensation, itching, or a metallic taste in the mouth. Other symptoms can include hives, a sensation of warmth, wheezing or other difficulty breathing, coughing, swelling of the mouth and throat area, vomiting, diarrhea, cramping, a drop in blood pressure, and loss of consciousness. These symptoms may begin within several minutes to two hours after exposure to the allergen, but life-threatening reactions may get worse over a period of several hours.
In some reactions, the symptoms go away, only to return two to three hours later. This is called a “biphasic reaction.” Often these second-phase symptoms occur in the respiratory tract and may be more severe than the first-phase symptoms. Studies suggest that biphasic reactions occur in about 20 percent of anaphylactic reactions.
See what happens inside the body during a food-allergic reaction.
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