Anaphylaxis

Anaphylaxis

What is it?
Anaphylaxis is a life-threatening allergic reaction to a substance that is normally harmless to most people.
Who gets it?
Anyone can suffer allergic reactions, but anaphylaxis occurs in people with an extreme sensitivity to a certain substance.
What causes it?
An allergic reaction occurs when the immune system produces antibodies and other disease fighting cells in response to an allergen. An allergen is a substance, most often an insect sting, drug, or food, that causes an allergic response. The antibodies release chemicals that actually injure the surrounding cells and cause the physical symptoms of an allergic reaction. Certain antibodies release histamines, which affect the skin, mucous membrane, mucous gland, and smooth muscle cells. Life-threatening allergic reactions can occur without any previous symptoms of allergy. Exercise or exposure to cold can trigger anaphylaxis in some people.
What are the symptoms?
Symptoms of anaphylaxis occur quickly and progress rapidly. They can include sudden anxiety and weakness, itching, swelling, hives, cramps, diarrhea, vomiting, difficulty breathing, tightness in the chest, very low blood pressure, loss of consciousness, and shock. Anaphylactic shock can occur within minutes and result in death. A patient in anaphylactic shock needs immediate medical treatment.
How is it diagnosed?
Anaphylaxis is diagnosed based upon its rapidly progressing symptoms. Your doctor may order blood and skin tests to identify specific allergens.
What is the treatment?
People who have anaphylactic reactions should, of course, avoid the allergens that trigger this response. Anaphylactic shock is treated with an injection of epinephrine, a hormone that stimulates the heart and relaxes the airways. This may be combined with an injection of an antihistamine, which counteracts the histamine produced by the immune cells during an allergic reaction. Those who are known to have severe allergies should carry a self-injection kit, including antihistamine tablets, for emergency treatment. However, they should still seek medical care after any type of anaphylactic reaction. Patients with anaphylactic reactions may need to receive supplementary oxygen and intravenous (IV) fluids. In severe cases, a breathing tube may need to be inserted to open the airways. People who are severely allergic may undergo a desensitization program, in which a series of injections of the allergen are given in increasingly larger doses until the body shows that it can be tolerated. This type of program must be administered by an allergy specialist and it may take anywhere from 15 to 20 weeks to develop an immunity. These are followed up with monthly booster shots.
Self-care tips
The only way to prevent anaphylaxis is to avoid known allergens. Some of the most common include bee stings, fish and shellfish, penicillin, latex, certain vaccines, nuts and seeds, and certain food additives. If you have a history of anaphylaxis, you should wear a medical ID bracelet containing information on your allergies.

This information has been designed as a comprehensive and quick reference guide written by our health care reviewers.  The health information written by our authors is intended to be a supplement to the care provided by your physician.  It is not intended nor implied to be a substitute for professional medical advice.