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If I Had - An Allergic Reaction - Dr. Robert Wood, MD
If I Had - An Allergic Reaction - Dr. Robert Wood, MD

(December 5, 2007 - Insidermedicine) Welcome to Insidermedicine's If I Had, where we get a chance to ask an expert what they would do if they had a medical condition.

Today, I have the pleasure of introducing Dr. Robert Wood, MD, a pediatric allergist and professor of pediatrics at the Johns Hopkins Children’s Center, and director of the Division of Pediatric Allergy and Immunology at Johns Hopkins University. A world-renowned expert in the treatment of peanut allergy, Dr. Wood is also the author of the book, "Food Allergies For Dummies."

We asked Dr. Wood for his thoughts on the detection and treatment of severe allergic reactions.

Dr. Wood: If I had hives eating peanuts, I’m probably less than two years old because most peanut allergies show up in the first two years of life. Most of it actually occurs on the very first exposure; the very first time that child is given a bite of peanut butter, or sometimes just a dab of it off their mother’s finger while she is making a peanut butter sandwich for their older brother. They are typically a very dramatic and obvious reaction, where in moments of getting that dab of peanut butter, hives begin. And the unknown at that point is whether this is going to stop at a few hives, or whether this is going to progress to something dangerous or life threatening. So, with the very first hive in that situation, we would say you need to see the doctor now, you need to do it by ambulance, you need to be seen in the emergency room – this is not a phone call to your pediatrician, this is “go to the hospital” where any of the life-saving measures that might be needed are available. The next step in the process is you should be leaving the hospital with a prescription in hand for self-injectable epinephrine, one of these pens that you carry around all the time in the event of your next reaction. And the next thing is you need to be seeing your pediatrician and then, typically, your pediatric allergist to have a more in-depth evaluation, and more in-depth advice about the precautions you need to be taking to avoid future reactions. That part of it doesn’t need to be done immediately. That can be done over the course of the next several weeks or months, as long as you got that prescription in the emergency room for that epinephrine to keep with you all the time.

Before visiting the emergency room, should I take any medications?

Dr. Wood: If you have Benedryl available, it would be very appropriate to take that. It would not be appropriate, however, to run out to the local drug store, get some Benedryl, come back home, see how your child is doing, and to not have made the 911 call or the trip to the emergency room. The Benedryl for a mild reaction may be perfectly effective, and if it’s one of these that only includes several hives, the Benedryl may be all you need. Benedryl, or other antihistamines, though, have no life-saving capabilities, so if your throat is going to swell, and especially if it’s going to swell to the point of being dangerous in terms of cutting off your breathing, an antihistamine will have no ability to reverse that, and that’s why the emergency room is really the key to the treatment.

What should I expect to happen at the emergency room?

Dr. Wood: When you arrive at your doctor, or more likely the emergency room, with that first reaction, you should expect to be evaluated immediately. This is a type of situation that can get out of hand very quickly, so you need to yell and scream at the triage nurse that “my child is having an allergic reaction and we need help right now.” You should be promptly evaluated by the nurse and the physician, and they will then determine whether this reaction is progressing to a point that you need additional medications or not. The observation period should typically be at least four hours because sometimes reactions appear to settle down and then flare back up a couple hours later. We call that a two-phased reaction, and about a third of food reactions follows this two-phase pattern. You should then be sent home with this prescription for medication for epinephrine that you would have on-hand 24 hours a day, seven days a week in the event of future accidental reaction.

What is epinephrine?

Dr. Wood: Epinephrine is the medicine that has life-saving capabilities in an allergic reaction. People are kind of used to this because they’ve heard of somebody who has a bee sting allergy, who carries epinephrine with them, or someone else that has a peanut or other food allergy whose been given a prescription for epinephrine. And this is the medication that will shrink down the swelling that may occur in your airway – that is the most dangerous part of an allergic reaction. It stabilizes your blood pressure and in the most severe allergic reactions, you’ll go into what’s called anaphylactic shock, where your blood pressure drops, and epinephrine can stabilize that as well.

How is definitive diagnosis made?

Dr. Wood: So once you get your next appointment with your pediatrician or your allergist, additional testing should be performed that will confirm your peanut allergy. That can be done either with a skin test or with a blood test. We would typically do both tests because they both provide useful information. And then, just as importantly, we would want to have regular follow-ups to have that allergy re-assessed and see if it’s one that is following the usual pattern of becoming more severe over time, or whether you may be in the lucky 20% who outgrows their allergy over time, where repeat testing at some regular basis would determine whether you might be in that group of patients.