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Allergies

Dermatology - skin rash

03/14/2007

Question:

A dermatologist has diagnosed a soap allergy to a skin rash that at first resembled an easy case of impatigo (untreated) that spread; however, the rash did not then form other "circles" but remained as "dots the size of finger tips". I could go along with the soap allergy, except that my brother also has moderate edema of the feet and legs with the rash.

The rash responded well to oral antibiotics and a 6-day course of prednisone; however, once those finished, the rash came right back, thus, the referral to a dermatologist and the subsequent diagnosis of soap allergy reaction.

The rash is red in color, and some do appear as blister-like, but do not ooze. The rash very rarely itches and doesn`t really hurt. The rash started on one leg as a circle the size of a half dollar, then spread outward and downward, then to the other leg and then to the trunk.

I don`t have a problem with the diagnosis of an allergy, but it doesn`t sound like an external allergy, but more like a reaction to something ingested. I have a severe allergy to all shell fish, but my brother doesn`t think it`s possible that he has it because he has eaten shellfish for years. HOWEVER, he has been eating quite a bit of oriental food lately, including several shrimp dishes. My allergy took years to build in reaction, with swelling of glands and throat with the last episode.

My concern is that if it is a reaction that responds to prednisone but comes right back, will another 7-day course of it "break the cycle". My son had this same type of reaction about 10 years ago and was told by a dermatologist that he was "stressed." Fortunately, he had previously had a very understanding allergist as a young boy (with multiple allergies) that we went back to. It took several weeks of prednisone, antihistimines and antibiotics to break the cycle. We never did find out what was causing the edema and rash, but it has never occurred again to the same extent. Interestingly tho` is that he can eat the typical shell fish but can`t eat calamari. I on the other hand can eat calamari but no outer shell fish. It does prove the point though that allergies have different reactions and often are just downright WIERD!

Any thoughts on the soap allergy diagnosis?

Answer:

The answer to this question is more involved and beyond the purpose of this forum.  However, contact dermatitis can be a serious problem.  Using an alternative soap product should alleviate the rash.  If it doesn't get better, then it is time try a different approach.   I would recommend a consult with a board certified internal medicine trained allergist who is experienced with allergic skin disorders.  They should be able to confirm whether or not this rash is from the soap or if other causes are responsible.

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Response by:

Jonathan   Bernstein, MD Jonathan Bernstein, MD
Associate Professor of Medicine
College of Medicine
University of Cincinnati