Allergic reactions to insect bites come with outdoor activity

Published 12:00 am Tuesday, May 12, 2015

Allergic reactions to insect bites come with outdoor activity

By Dr. David Berry
ER Physician

Of all the happy summertime childhood memories many of us have, stinging insects are not part of them. Wasps, bees, hornets and yellow jackets are all too common to this area of the country for their nasty little but painful tail ends.

As people tend to spend more time outside during the warmer months, so do these stinging insects. Most of us at one time or another have experienced one or all of the above insect stings.

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Stinging insects are a family of insects in which God has provided a toxin to inject into prey to paralyze or kill so they can more easily consume them.

While humans are not the main target of these insects, they do not hesitate to inflict the same punishment when we get in the way.

Fortunately, the toxin itself is rarely in sufficient quantities to kill a human. However, we can experience life threatening results from our own body’s reaction to this toxin. What we are really talking about is an allergic reaction.

Our immune system fights unwanted intruders; be it bacteria or toxin from a wasp sting. When our body over-reacts to these foreign substances we experience an allergic reaction. The term allergic reaction is a general wording that describes a broad spectrum of responses by our body.

This spectrum can range from itching at the site of the sting to the extreme end called anaphylaxis in which all the organ systems respond to the toxin or intruder. This extreme end of the allergic reaction spectrum is what we are really concerned about from an emergency setting when our child comes to the ER with an insect sting.

During anaphylaxis a molecule in our body called histamine, along with some other immune response molecules, are released in large quantities. These molecules cause the vessels in our vascular system to dilate. This in turn causes our blood pressure to fall, termed “hypotension.” If we don’t have enough blood pressure we can’t get blood to important places in our body like the brain.

Also, our bronchioles (tubes that bring air to our lungs) constrict which prevents air and thus oxygen from getting into our lungs.

As one can imagine if we can’t get oxygen to our lungs this is a critical situation. Wheezing is a common sign that our bronchioles are constricting and immediate life saving intervention is needed. Anyone who has asthma knows what this is like. In fact, asthma is a type of allergic reaction.

The mainstay treatment for anaphylaxis is epinephrine. This drug blocks histamine and this reverses all the above symptoms.

Since we are dealing with a condition that has a broad spectrum, there are other medications that can be used without epinephrine for milder cases. Benadryl is an over-the-counter medicine that blocks histamine as do H2 blockers such as Tagamet and Pepcid (but not Prilosec). Finally, steroids are strong anti-inflammatory medicine but take longer to work.
So how do we know who is going to go into anaphylaxis from an insect sting? The short answer is we don’t. That said, those patients that have severe types of allergic reactions usually know they do and can have a much lower threshold for getting to the ER after an insect sting.
Now that we are done with the scary part, we can talk about more common treatments for insect stings. The vast majority of us do not go into anaphylaxis from an insect sting. Those of us in this category can usually treat the sting at home. There are as many home remedies as there are stories about summer activities. Many of them work.

That aside, usually some Benadryl cream at the site of the sting and even Benadryl by mouth is enough to get us through the immediate period following the sting. The other topic to consider is infection from an insect sting.

Most stings do not become infected and most medical literature does not recommend giving antibiotics unless an infection is confirmed. This will usually not be apparent for several days.
So what are you saying, doc? The main emergent concern with an insect sting is whether our patient will have the most severe type of allergic reaction called anaphylaxis. Mild cases can be treated with Benadryl cream and pills. Follow up with your family physician if you suspect an infection has begun. While rare, if you have any symptoms other than pain at the site of the sting, especially, breathing difficulty or you are prone to severe allergic reactions, get to the ER immediately!

Enjoy the outdoors this summer. It’s going to be hot so keep an eye out for our stinging neighbors.
Ask Dr. Berry a question.
David M. Berry, M.D.
Tri-Lakes Medical Center