Gettysburg Medical News
 The Clinical View
 by P.E. Hoffsten, MD
 7 September 2005

ALLERGIC SKIN PROBLEMS

            The lady was 36 years old and had very fair skin.  She indicated that she often had problems with skin rashes in the past but she just couldn’t figure out what was happening now.  On examining her present rash, it was seen to cover the front, back and sides of her trunk about equally.    It was relatively strong in the underarm areas and showed very little rash on the outside extensor surface of her arms.  Her legs were really not affected at all.  The rash was reddened, very itchy and slightly raised especially in the underarm area.  She said it had been present for about two weeks and seemed to be getting worse.  She said that she tried changing her antiperspirant and some body lotions that she used but to no avail.

            I inquired as to whether or not she was using any new soap or had purchased any new garments and she indicated that she really had not.

            It was quite apparent that her problem represented a “contact dermatitis”.  This means that when certain chemicals come in contact with a certain area of the skin, that skin becomes very irritated.  Perhaps one of the most famous forms of contact dermatitis is poison ivy where the person brushes against a plant that has a relatively harmless chemical on it.  However, this chemical is very attractive to our immune system and our body’s immune system feels the need to expel the poison ivy chemical.  The war between the poison ivy chemical contact and the body’s immune system results in a severe dermatitis that occurs.

            The best way to avoid contact dermatitis is of course to avoid the chemical causing it.  But there are so many allergy causing chemicals in our world today that avoiding all of them is almost impossible.

            When the allergy occurs and the itch develops, there are several over-the-counter medications that may be of some help.  Among these are Benadryl which is an antihistamine drug.  Note that histamine is our own skin chemical that makes the itch occur and antihistamines can decrease the itch substantially.  In addition, there are products such as Calamine lotion that may help some individuals.  I have never been very impressed with it myself but for certain people it does seem to be a significant help.  Finally, there is cortisone containing creams or pills that can be taken on a short term basis that will markedly decrease the allergic reaction.  Cortisone containing creams that are relatively weak are available over-the-counter without a prescription.  For the stronger and more effective cortisone creams and cortisone pills, a prescription is required.  Usually, these are only necessary for 5-10 days while the allergic reaction resolves.  This assumes, of course, that the allergy causing chemical gets recognized and stopped.

            The lady above was found to be allergic to laundry softener that she only used on her blouses.  When this was stopped the rash went away.  But it took a trial of stopping the softener and then adding it back three weeks later.  When the softener was again put in the drying cycle of her laundry the rash started again thus proving the cause of the rash.  Problem solved.

            So what are the basic allergy causing chemicals in our environment?  One of these is nickel which is a metal component of some jewelry.  People usually recognize when they have such a problem because their pierced earrings cause an irritation right around the piercing site on their ear (or in today’s world almost any body part).  Rarely gold containing products can cause allergies.  This is relatively unusual.  Lastly, cobalt is a metal in some jewelry products that can cause allergies.  These three allergies are usually relatively easy to recognize because they occur at the site where the jewelry is applied.  Ones that are much harder to recognize include balsam which is a plant product in many cosmetics, medications, flavorings, and perfumes.  Certain perfumes independent of balsam can cause allergic problems and these are incorporated in body lotions and cosmetics.  Medications that commonly cause allergic reaction include thimerosal in mercurochrome, neomycin in antibiotic ointment and bacitracin that occurs in many over-the-counter antibiotic ointments.  Lastly, formaldehyde is a common preservative in many products and this can be highly irritating. In recent years, one of the most common allergies that have occurred in medical professionals is latex allergy to the rubber gloves that are worn.  This can be very severe but today is easily recognized and avoided.  As mentioned above, the most famous allergic causing chemicals are the products in poison oak, poison sumac and poison ivy.  When these chemicals get on a susceptible person’s skin, they can develop a terrible allergic reaction that itches horribly.

            Certain misconceptions about allergic dermatitis need to be addressed.  The first of these is that whatever the allergen, it must be new.  People can often use the same product for many years and then become allergic to it.  We are not sure exactly how this happens but just because somebody has been using something for a long time it does not mean that it is not the allergic causing product.  Secondly, it must be recognized that allergy causing agents may not react within a day or two of the time a person is exposed.  It may take a week or 10 days before a rash will develop to something that was contacted long before that.  If an allergy is once established, then the reaction will come much more quickly on the second or third or fourth time the person experiences that agent.  But the very first time an allergic reaction occurs, it usually takes a longer period of before the allergic reaction occurs.  Lastly, it needs to be noted that the dose of the chemical that caused the reaction is highly variable.  Sometimes, simply brushing against a product such as poison ivy can cause a severe dermatitis.  The chemical that causes this dermatitis can barely be detected on the skin but our immune systems are very, very sensitive and they can pick up small amounts of allergen and react violently to it.  I often hear that a person buys the most expensive cosmetics or detergent and that it can’t be causing the problem.  No matter what the cost of the product, allergens can be present and the idea that more expensive products cause fewer allergies or are “allergy free” is simply not true.  Some of the most difficult allergic rashes to diagnosis are those in which the direct contact occurred on the person’s leg but then they scratched their leg and then some other part of the body; then the allergy develops on the other part of the body that wasn’t really contacted originally.  These can be very hard to figure out.  Finally, to make things very complicated  allergic rashes are often thought to occur symmetrically on both sides of the body.  For some reason, we don’t understand why an allergy developing to a contact area can result in a rash only in part of the contacted area when other areas were also exposed.  Lastly, it is thought by some people that allergic dermatitis will not affect the palms or the soles of the body because the skin is so thick.  Allergic reactions of varying intensity can occur in all parts of the body including the palms and soles.

            The healthcare professionals at your local clinics are aware that allergic dermatitis is one of the most common problems that we experience.  Trying to find the culprit allergen and getting this out of the person’s environment can be a very difficult problem.  Help with this and treatment for the rash and the itch that occurs is available at your local clinics.