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Hiking through a nature preserve, John decides to push over a fallen, rotting tree to see what’s underneath. Out swarms a mass of angry yellow jackets and one stings him on the arm. John’s arm begins to swell and he becomes mildly flushed. Within seconds, he wheezes and his breathing becomes labored. Without rapid and immediate treatment, his condition could become life-threatening.

Allergic Reactions

John experienced anaphylaxis, a life-threatening allergic reaction requiring emergency treatment. Emergencies caused by hypersensitivities can happen in both children and adults, and can affect a person’s whole body. Upon exposure, there usually are early warning signs such as mild flushing, itching of the palms and soles, and a slight cough or clearing of the throat. These mild symptoms can rapidly progress to a full-blown attack that can include tightening of the airways causing breathing difficulty, itching over the entire body, reddened and itchy wheals on the skin, swelling of the tongue, and in severe cases, nausea, vomiting, and a dangerous drop in blood pressure.


The most common causes of hypersensitive reactions are the extracts used in allergy immunotherapy (allergy shots). Since allergy immunotherapy is a cornerstone of treatment for both allergic rhinitis and asthma, the frequent use of these preparations is responsible for the frequency of reactions. If you have a large, localized reaction or mild systemic reactions to your allergy shot, you may be predisposed to anaphylaxis. Systemic symptoms include mild flushing, palpitations, and minimal itching within 30 to 40 minutes of the injection.

If you have bronchial asthma, you are at greater risk than someone with simple allergic rhinitis, and your treatment will be more cautious.

Some people can have an anaphylactic reaction to contrast dyes used during certain diagnostic tests. If such tests are required, the use of nonionic contrast material should be considered, as well as prophylactic pretreatment with antihistamines and steroids.

Certain drugs can cause anaphylaxis, and the risk can vary with how they are administered. For example, penicillin is more likely to produce anaphylaxis when given intramuscularly, less likely if given intravenously, and least likely if given orally.

A number of foods, especially nuts and shellfish, are associated with anaphylaxis. Anaphylactic reactions are more common in people who are sensitive to crustaceans such as mussels. Some people are so sensitive that an inhalant exposure (e.g., cooking fish) can trigger the reaction.

If you have had a hypersensitive allergic response to an insect sting, there is good news! Insect venom immunotherapy is 99 percent protective against subsequent anaphylactic reactions.


The best way to treat these life-threatening situations is to avoid situations where they might occur. Know what drugs cause reactions and tell your doctors; know what foods are the villains and avoid them; be more careful than John when hiking in the woods.

In cases of anaphylaxis, emergency treatment with epinephrine (adrenaline) is required. If you are predisposed to or have a history of reactions, such as to venom or food, you might be advised to carry a preloaded adrenaline syringe (EpiPen) and oral antihistamines. The EpiPen has no exposed needle, so people often experience less anxiety. The tip of the pen is pushed against the skin, and the pressure causes the needle to pop out and administer the proper epinephrine dose.

If the reaction cannot be warded off, emergency medical treatment may also include other medications fluid replacement, CPR, or if the problem is a sting or an injection, a tourniquet to stop the blood from returning to the heart.

Airway Obstruction: Symptoms and Treatment

Airway obstruction may develop in the upper or lower chest. If it is in the upper airways, symptoms appear rapidly and you may be hoarse. A critical feature is difficulty when breathing in that leads to a “seal-like” bark heard at the end of inspiration. In lower respiratory obstruction (asthma), breathing in won’t be difficult; instead, breathing out will be severely prolonged.

Treatment of obstructions to upper airways may include antibiotics, steroids, or local constrictors such as nebulized epinephrine. Emergency management of asthma in the lower airways requires bronchodilators, oxygen, and potent anti-inflammatory medications (such as steroids and antibiotics).

John, although hypersensitive to insect venom, carried an EpiPen and antihistamines with him. With quick treatment, the sting caused him no further problems.

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