Avoidance and education are the mainstays of prevention therapy for those who suffer from severe allergies. However, the allergen cannot always be avoided, so it is important to know what emergency measures to take (i.e., epinephrine self-injection) when exposure occurs. It is also important to be on guard for the recurrence of an allergic reaction in the hours after the main reaction has occurred, also known as a biphasic reaction.

For some allergies, immunotherapy may be used to desensitize the allergic patient to subsequent allergic reactions.

 
Avoidance

Avoiding identified allergens is critical for people who suffer from severe allergies. People who may be susceptible to anaphylaxis should make a point to educate themselves about their allergen. For example, those with food allergies should inquire about food ingredients that may provoke a reaction, while people suffering from latex allergy need to find out which consumer products contain latex.

Many allergic reactions to medications can be avoided by better communication among the physician, pharmacist, and patient—be sure to mention any drug allergies that you have. People with insect venom allergies should take basic precautions regarding footwear, clothing, and use of perfumes to minimize potential contact with bees, fire ants, or other stinging insects when engaging in outdoor activities. Those with medication allergies may want to wear an identification bracelet describing their allergy.

It is also important that the allergic person's family, friends, and—in the case of children—teachers and schools know about and understand the ramifications of the allergy, so that they can aid in the prevention of anaphylaxis.

Emergency Treatment

Severe allergic reactions are frequently unavoidable because foods may contain unknown ingredients, insects range widely, and latex can be found almost anywhere. Once anaphylaxis begins, the treatment of choice is an immediate injection of epinephrine, sometimes called adrenaline, which is effective for 10 to 15 minutes, followed by emergency medical attention.¹ Since there is no way to predict the severity of a reaction, and because anaphylaxis can progress so rapidly, waiting for the paramedics or ER staff to administer epinephrine may greatly increase the risk of death. Therefore, it is essential that anyone with a history of anaphylaxis keep epinephrine auto-injectors, such as EpiPen^® auto-injectors, on hand at all times and be prepared to use these whenever a reaction occurs.

Epinephrine rapidly constricts the blood vessels, relaxes the muscles in the airway and lungs, reverses swelling, and stimulates heartbeat, thereby reversing the most dangerous effects of an anaphylactic reaction. However, it does not replace medical help. Epinephrine provides the patient with emergency therapy, but immediate follow-up care by medical professionals will provide the patient with the full treatment necessary to counter an anaphylactic episode. The sooner a patient receives epinephrine, the better that patient's chance of survival. Extra vigilance is also essential after an episode of anaphylaxis.

Side effects of epinephrine may include palpitations, tachycardia (an abnormally fast heartbeat), sweating, nausea and vomiting, and respiratory difficulty. Cardiac arrhythmias may follow administration of epinephrine. Patients need to be carefully instructed by a physician about the circumstances under which this life-saving medication should be used.

Many physicians also recommend that antihistamines such as diphenhydramine be administered to lessen the symptoms of an allergic reaction, but antihistamines should only be taken in addition to epinephrine for the treatment of anaphylaxis and should not be considered a substitute for it. Only epinephrine can halt the potentially deadly effects of anaphylaxis.

Biphasic Reaction

As many as 25% of people who have an anaphylactic reaction will experience a recurrence in the hours following the beginning of the reaction and require further medical treatment, including additional epinephrine injections.^2-4 This secondary reaction is called biphasic, meaning two phases.

References

1. AAAAI. The use of epinephrine in the treatment of anaphylaxis. Position statement #26. Available at: www.aaaai.org.
    
2. Stark BJ, Sullivan TJ. Biphasic and protracted anaphylaxis. J Allergy Clin Immunol. 1986;78:76.
    
3. Brazil E, MacNamara AF. "Not so immediate" hypersensitivity—the danger of biphasic anaphylactic reactions. J Accid Emerg Med. 1998;(4):252-253.
    
4. Korenblatt, et al. A retrospective study of the administration of epinephrine for anaphylaxis indicating need for more than one dose [abstract 234]. ACCP. 1998.