Anaphylaxis

The Facts

Anaphylaxis is a medical emergency. This serious type of allergic reaction occurs after a person is exposed to an allergen (a substance they are allergic to), such as certain foods, medications, or insect stings. The body's immune system quickly reacts, causing swelling of the face and throat, difficulty breathing, dangerously low blood pressure, and leaky blood vessels. These effects can lead to shock. If not treated quickly, anaphylaxis can be fatal.

According to a study conducted in 2001, anaphylaxis affects 1.2% of the American population, and perhaps as much as 15% of the American population. Avoiding the allergen and knowing what to do if you are exposed are the keys to managing the problem.

Causes

Just about any substance can bring on an anaphylactic reaction. But anaphylaxis is most commonly caused by:

• allergy shots
• blood products
• foods such as nuts, shellfish, eggs, fruits, and berries
• insect bites or stings
• latex (a type of natural rubber found in certain medical supplies)
• medications such as antibiotics, vaccines, anti-inflammatories and painkillers, insulin, and dyes used for X-rays or MRI scans

In up to 20% of cases no cause for the anaphylaxis is ever found. The medical term for this is idiopathic anaphylaxis.

When a person with an anaphylactic allergy is exposed to an allergen, their immune system goes into overdrive. The substances it produces, such as histamine, are intended to protect the body from a foreign invader. But they go much too far, causing the throat to swell up and the blood vessels to leak fluid. This leads to the symptoms of anaphylaxis and can be life-threatening.

People with asthma, seasonal allergies, or eczema are at a higher risk of anaphylaxis. Before age 16, anaphylaxis is more common in boys than in girls. After age 30, it is more common in women than in men. Race and geographic location do not affect the risk of anaphylaxis.