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Penicillin allergies and skin testing

I don't actually have any idea if I have a penicillin allergy. However, when asked if I have any allergies to medications, I do mention that I have always had horrendous GI effects from taking *cillins, and for whatever reason, it winds up on my chart as an allergy. I just won't take *cillins which are prescribed to me (sort of a moot point these days, because I've reduced the going-to-the-doctor to the point where no one has a chance to prescribe me anything. Huge improvement all around and much cheaper, too) anyway. I do have _lots_ of other allergies, however, including a shellfish allergy (not all shellfish: crab, prawns, lobster, shrimp, etc.) that leads to hives and monster migraines and GI problems; milk products cause GI and respiratory problems and a list of other things that I try to avoid because they seem to trigger respiratory problems and really, why go there?

Anyway. My husband sent me something recently asserting that penicillin allergy was over reported, and I was skeptical, however, here is an interesting development. Someone did a bunch of skin testing!

http://www.medpagetoday.com/MeetingCoverage/AAAAI/56591

Initial N = 225. People who had a health record stating they were allergic to penicillin.

"Patients on antihistamines and beta-blockers were excluded from the trial."

This got them down to 206. They skin tested them. 201 did not have reactions to the skin test.

"A cohort deemed likely to benefit from penicillin therapy was prioritized for inpatient testing. In patients who were nonreactive to both tests, a penicillin G test with 500 mg of oral amoxicillin challenge was administered."

The size of this cohort is not stated in this summary (is it the 206? Or something else?). Of this group, one person reacted to saline (!). 10 people had a negative histamine test (what does that mean anyway?) and were removed.

Overall, out of the 206 that survived from the original 225, only 5 had positive reactions to skin testing. Everyone else got the label taken off their chart and could be prescribed *cillins. The idea is NOT just to save money -- some of those other abx have really disturbing side effects (altho not as bad as dying from a penicillin allergy, presumably).

I am, however, a bit flummoxed. On the one hand, I'm sort of tempted to go in for skin testing now. On the other hand, I'd have to completely go off allergy meds to do so. So. Hrm. Maybe during one of those months when I'm super ambitious and am not reacting to anything at all.

ETA: Here is an explanation of the saline and negative histamine test results and what they mean when doing allergy testing. Basically, the people who did this study did the study according to current best practice skin testing practice.

http://www.healthcommunities.com/allergy-testing/overview-types-of-allergy-tests.shtml

And let me tell you, back in the 1980s, they didn't do it this way, and I suspect that's why I knew a couple people who were allergic to everything (even things they said didn't bother them, but which skin tests showed they were allergic to). Nice to know they're getting this all sorted out!

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( 1 comment — Leave a comment )
ethelmay
Mar. 7th, 2016 07:20 pm (UTC)
"Patients who react to this [saline] solution may have skin that is too sensitive to allow correct interpretation of allergy skin tests."

Yeah, that would be a bunch of my family, at least as children. One of my brothers, for instance, has or had mild dermatographia, which is probably related. I remember reacting to more or less everything on that grid of skin tests (though things like pollen and cats and so forth that I really do react to came out much bigger welts). I recall Mom saying, possibly quoting some other doctor, that we were "allergic to everything except penicillin," which was of course wildly inaccurate, but it is true that none of us has any trouble with penicillin derivatives that I've heard of.
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