Anaphylaxis is the most severe of all allergic reactions and can result in difficulty breathing, a sudden drop in blood pressure with subsequent anaphylactic shock, and even death. Anaphylaxis is a medical emergency that requires immediate recognition, prompt medical treatment, and follow up care by an allergist.
It has been estimated that up to 15% of the population is at risk for anaphylaxis. Anaphylaxis can occur within minutes after exposure to a substance to which one is severely allergic. The most common substances that trigger anaphylaxis are foods, medications, and insect stings.
Anaphylaxis is triggered when an allergen (food, medicine, insect venom, etc.) comes in contact with antibodies (IgE) in the blood or tissues previously formed by prior exposure to the allergen. This antigen-antibody reaction results in a rapid cascade of cellular events leading to the immediate release of large amounts of histamine and other chemical mediators.
These chemical mediators, when exposed to the smooth muscles of the lungs, can quickly lead to constriction of the bronchial smooth muscle causing wheezing, tightness in the chest, and difficulty breathing. Exposure to blood vessels generally causes urticaria, or hives, and can lead to vasodilatation of the peripheral circulation resulting in low blood pressure and possibly shock. Reactions usually begin within seconds to minutes of exposure, but may be delayed. In general, the quicker the onset of symptoms, the more severe the reaction may be. Sometimes symptoms resolve, only to recur or progress a few hours later.
Anaphylaxis is, by definition, “systemic”. It therefore can affect multiple organ systems, including the skin, respiratory, circulatory, and gastrointestinal systems. Symptoms of anaphylaxis can vary from mild to severe, and are potentially deadly.
The following is a list of possible symptoms that may occur alone, or in any combination:
A recent study done at the Mayo Clinic found that food allergy is the most common cause of anaphylaxis. In their study of patients presenting to the emergency room over a ten year period, 33% of anaphylaxis cases were caused by foods. Insect stings accounted for 19% and medications caused 14% of all anaphylactic reactions.
In addition to the administration of rapid acting antihistamines, the effective medical treatment of anaphylaxis requires the immediate administration of epinephrine (adrenalin). Patients with a history of anaphylaxis or those identified as high risk for anaphylaxis should carry an epinephrine auto-injector, such as Epipen, with them at all times. The quicker epinephrine is given to the onset of symptoms, the better likelihood of successful treatment. It is sometimes necessary to give a second or even a third dose if symptoms persist. While medical treatment is being initiated, medical assistance should be sought as further therapy may be necessary. Even after receiving immediate medical treatment on site, one should be transported to a medical facility or hospital for further evaluation.
Any person who has had an anaphylaxis episode should consult an allergist in order to: