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Anaphylaxis
(The Most Serious Allergic Reaction)
It is worth mentioning a few general observations regarding the features of anaphylactic reactions. Be aware, however, that these guidelines are not always consistent or reliable for a particular individual.
The severity of the reaction varies from person to person.
Subsequent reactions to the same trigger are typically similar in nature.
The more rapid the onset of symptoms, the more severe the reaction is likely to be.
A history of allergic disease (rhinitis, eczema, asthma) does not increase the risk of developing IgE mediated anaphylaxis, but it does incline the person to a non-IgE mediated reaction.
Underlying asthma may result in a more severe reaction and can be more difficult to treat.
The risk of anaphylaxis may diminish over time if there are no repeated exposures or reactions. However, a person at risk should always expect the worst and be prepared.
What will I feel during an anaphylactic reaction?
The symptoms of an anaphylactic reaction may occur within seconds of exposure or be delayed 15 to 30 minutes or even an hour or more later (typical of aspirin and similar drugs). Early symptoms are often related to the skin. Flushing (warmth and redness of the skin), itching (often in the groin or armpits), and hives are common initial findings. These symptoms are often accompanied by a feeling of “impending doom,” anxiety, and sometimes a rapid, irregular pulse. Throat and tongue swelling resulting in hoarseness, difficulty swallowing, and difficulty breathing frequently follow. Symptoms of rhinitis or asthma may occur causing a runny nose, sneezing, and wheezing, which may worsen the breathing difficulty. Vomiting, diarrhea, and stomach cramps may develop. About 25% of the time, the mediators flooding the blood stream cause a generalized opening of capillaries (tiny blood vessels) which results in a drop in blood pressure, lightheadedness, or even loss of consciousness. These are the typical features of anaphylactic shock.
What happens next?
There are three possible outcomes:
The signs and symptoms may be mild and fade spontaneously or be quickly ended by administering emergency medication in the form of epinephrine (adrenaline). In this outcome, the symptoms do not subsequently recur from this particular exposure.
After initial improvement, the symptoms may recur within 4 to 12 hours (late phase reaction) and require additional treatment and close observation. Recent evidence suggests that a late phase reaction occurs in fewer than 10% of cases.
Lastly, the reaction may be persistent and more severe, thus requiring intensive medical treatment and hospitalization. This may occur up to 20% of the time with certain exposures.
Epinephrine, which is also known as “adrenaline,” is a drug that acts immediately to cause the blood vessels to contract, thereby preventing fluid leakage. Epinephrine also helps relax the bronchial tubes, thus relieving breathing difficulty. It also lessens stomach cramps and stops itching and hives. More importantly, epinephrine helps prevent the release of more mediators.
Allergy Alert
Beta-blocker medications commonly used to treat high blood pressure, angina, thyroid disorders, migraines, or glaucoma can make it very difficult to reverse anaphylactic reactions, which may then become severe.
Could it have been something else?
Several disorders may appear similar to anaphylaxis. Fainting (vaso-vagal reaction) is the reaction that is most likely to be confused with anaphylaxis. The key differences are that in a fainting episode, the affected person has a slow pulse, cool and pale skin, and no hives or difficulty breathing. Other conditions, such as heart attacks, blood clots to the lungs, and panic attacks can also be confused with anaphylaxis.
Diagnosis – Rounding Up the Likely Suspects!
Once you think that you might have had an anaphylactic reaction, the first order of business is to see an allergist. The allergist will assess whether or not the reaction was indeed allergic in nature. Usually, a careful and detailed medical history and selected blood or skin tests can identify the cause. Be prepared to recall your activities before the event, the food and medications you ingested, and whether or not you had any contact with rubber products.
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