Contact Dermatitis

Contact dermatitis is a type of reaction in which local areas of the skin become inflamed upon contact with certain substances. The area of skin itches, turns, red and may break out in papules, or blisters. In time, the lesions thicken and crack, and the skin changes color. Usually, a well-defined border develops between the affected area arid the normal skin. The causative agent may act as an irritant or as a sensitizer, inducing delayed allergic reactions. Delayed contact allergy is not mediated by allergic antibodies, as it is in hay fever, instead, the allergy is produced by certain sensitized cells (lymphocytes) in response to an antigen, the substance that causes the irritation.
The antigens responsible for contact allergy are usually small (in terms of molecular weight) chemicals that must first combine with local proteins before becoming antigens. Poison ivy, metals, cosmetics, and medications are common causative agents. The material that causes the reaction is an oil resin called urushiol, found in the sap of the plant. Penicillin and antihistaminic creams are also frequent causes of contact allergy. Ethylenediamine, a chemical often used as a stabilizer in many topical medications, is a potent sensitizer and is the cause of numerous reactions to topically administered medications.

Sources:
Allergy Be Gone	American College of Allergy, Asthma & Immunology	Auckland Allergy Clinic
Eallergy.net	American College of Allergy, Asthma & Immunology	bbc.co.uk Health

Books on Allergies

My House Is Killing Me! The Home Guide for Families With Allergies and Asthma

Editorial Review
Asthma and allergy sufferers, this book is essential reading: it will answer all your questions about why you suffer in your own home and what you can do to prevent it. May, an air quality investigator and president of a home investigation company, takes you on a tour of your home, both interior and exterior, with a detailed description of the organic and inorganic substances that are making you ill. He covers every room, including the basement, attic, laundry room, garage, heating and air-conditioning system(s), and nooks and crannies that you probably forgot about. He explains how insects, molds, bacteria, yeast, dust, moisture, larvae, pet dander, fabric fibers, smoke, and many other agents can trigger an episode and how to eliminate them permanently.

Reader's Review - A really helpful book
I've read several other books on this topic,plus consulted with a doctor specializing in environmental illness (EI), but I still learned a lot from this book and it's my favorite. Why? Because it's full of practical, doable things YOU can do around your house to make it a healthier environment. Many of the other EI folks want you to tear your house apart, even when there's no evidence that your house is the culprit. This approach makes far more sense. Some patients must, of course, take drastic measures, but many of us do not. Start with this book, then read John and Lynn Bower's books if you need more detail. It's an easy read and cheap. I highly recommend it.