Archive for May, 2008

Myth: Urticara (aka hives) only occur as a result of an allergic reaction.

Monday, May 5th, 2008

Urticaria are those itchy, pink to red, raised skin lesions that are surrounded by a red halo. Although somewhere in the range of 90% of anaphylactic reactions are accompanied by urticaria or some sort of skin reaction, there are many other non-allergic causes. Some of these include physical factors (e.g., pressure, cold), infections (viral, bacterial and parasitic) and systemic illnesses. With all of these possibilities, it is not unusual when no cause is found.

So question (but don’t exclude) the diagnosis of anaphylaxis when there is no sign of skin involvement. Conversely, don’t jump for the epinephrine when an urticarial eruption is the only finding.

Dr. David Johnson

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Myth: Once a person has had an anaphylactic reaction to a substance, all subsequent exposures will invariable lead to similar or worse reactions.

Monday, May 5th, 2008

There is no question that recurrent reactions can follow re-exposure. As it turns out, however, the probability as reported in the medical literature is considerably less, about 50% for bee stings, for example. These re-exposure reactions can be less severe than the prior reaction.

Taking reasonable steps to avoid re-exposure is as important as being prepared to recognize and treat a reaction should it occur. For some people with recurrent severe reactions, immunotherapy (aka desensitization) can be a very effective deterrent. It is equally important to remember, however, that based on these statistics, not everyone needs to be treated following a re-exposure. Only treat those who develop signs and symptoms consistent with a true anaphylactic reaction.

Dr. David Johnson

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