Anaphylaxis: An Allergic Reaction That Can Kill : Part 2

by Food and Drug Administration (FDA)

(Page 2 of 2)

There are numerous other less common precipitators of anaphylactic or anaphylactoid reactions. Medical reports point to substances as varied as cancer drugs, a hair dye ingredient, topical antibiotics, cornstarch surgical glove powder, milk protein in a diaper rash ointment, cabbage, pig insulin, dextran (used in intravenous drug therapy), muscle relaxants, and wines that contain sulfites. (Because sulfites in foods, wine, beer and drugs can cause severe adverse reactions in some people, FDA has taken steps to curtail the widespread use of these preservatives and to help warn consumers about products that contain them.)

Despite the numerous foods, chemicals, drugs, and physical precipitators known to cause anaphylaxis, in most instances the cause of a reaction is unknown (idiopathic). Researchers at Northwestern University Medical School in Chicago recently reported on 73 patients with idiopathic anaphylaxis. "Idiopathic anaphylaxis," the researchers wrote in the February 1987 Archives of Internal Medicine," can be extremely frightening to both patient and physician when no inciting source is found. Patients often attribute their symptoms to foods or food additives, and many patients become increasingly frustrated by the unpredictability of their reactions." Three patients followed by the scientists became afraid to eat because they feared it would induce anaphylaxis. Reassurance helped rid the fear in two of the three. The third patient consulted another physician who performed laboratory tests and advised her not to eat eggs, soybeans, chocolate, or fish. Despite avoiding these foods, she continued to have anaphylactic episodes and lost more than 18 pounds in two years.

In the October 1987 issue of Obstetrics and Gynecology, Jay E. Slater, M.D., and his colleagues at the National Institutes of Health in Bethesda, Md., reported a study of five women with recurrent idiopathic anaphylaxis whose episodes were thought to be related to secretion of the hormone progesterone. The researchers speculated that the hormone might somehow foster release of mediators from mast cells. The women were treated with a drug that lowered their progesterone levels by stopping their menstrual periods, and three of the five stopped having attacks. The researchers noted certain common characteristics among the women who responded successfully (such as a history of previous ovarian problems and diagnosis of the problem after age 36), and concluded that the drug would most likely benefit patients with similar characteristics.

When possible, the best course for preventing anaphylaxis is, obviously, to do what Jacki Kwan does: avoid the instigator — in her case, pistachios. Michael A. Kaliner, M.D., of the National Institute of Allergy and Infectious Diseases recommends, for example, that "people with known sensitivity to insect stings should avoid areas where they are likely to encounter stinging insects; always wear shoes when walking in grass; avoid smelling like a flower by using perfumes or other scented products, such as scented soaps, aftershaves, or suntan lotions; and avoid looking like a flower by wearing flowered or brightly colored clothing." (Dark colors like brown and black may provoke an attack; bees are least attracted to white and light khaki.)

Next best is to be prepared for an attack. Several emergency treatment kits are available by prescription and should always be carried by people who know they are prone to anaphylaxis. All the kits contain epinephrine, which stops the action of the mediators, preloaded in the injecting device. One type contains a notched syringe to ensure the correct dose is given. Richard Nicklas, M.D., an allergist in FDA's Center for Drug Evaluation and Research, cautions that "The patient or another person should be fully instructed in its use by the prescribing physician." Other kits contain a spring-loaded injector that automatically injects a predetermined dose of the drug when it is pressed against the thigh.

Some kits also contain a tourniquet and an antihistamine. But an antihistamine is not an effective emergency treatment. It is included in the kit to reduce symptoms that may continue after treatment with epinephrine. Anaphylaxis must be treated immediately with epinephrine. The tourniquet is for use in the case of an insect sting on an arm or leg. First the stinger should be flicked. The tourniquet should be applied above the site of the sting and loosened every 10 minutes to allow sufficient blood circulation. If possible, a cold pack should also be applied. The cold causes the blood vessels to constrict, which slows venom getting into the bloodstream.

Emergency kits are not a substitute for professional medical help. They are intended for patients to use until they can reach a doctor or hospital. The patient should not hesitate, however, to use the medication immediately, as directed by the physician.

Finally, treatments to reduce sensitivity in a patient (allergen immunotherapy), or to completely desensitize a patient (desensitization therapy), are effective for some patients. Immunotherapy involves injecting the allergen, such as insect venom, in increasing amounts over a period of years. The injected allergen stimulates production of IgG antibodies, which confer protection from the substance.

Desensitization is done in patients who need treatment with a life-saving drug to which they are allergic — usually penicillin — and for which there is no effective substitute. Unlike allergen immunotherapy, desensitization is done in the hospital over a short period, beginning with extremely diluted solutions of the allergen. The patient is watched carefully as the dose is gradually increased and may be treated with antihistamines or other medicines if symptoms occur.

Experts disagree about whether certain individuals are predisposed to anaphylaxis. Many feel that people with a history of allergies are more likely to have an anaphylactic episode; others are unconvinced that this or other factors — such as age, sex, race or geographic location — predispose a person to it. One thing is clear, though: Previous exposure to the allergen usually precedes the anaphylactic reaction. Sometimes people will notice that an allergen makes them feel bad in some way — perhaps mild itching or upset stomach. This may indicate that future exposure will produce a more severe reaction.

Whatever the reason for anaphylaxis — as Johns Hopkins' Lichtenstein says, its outcome is generally a yes or a no. Patient awareness, preparedness, and prompt action can help raise the tally in the yes column.

About the Author

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