Recently I received a rather heated e-mail in which a reader objected strongly to one of my previous writings. I had concluded that a specific ingredient is generally safe for use in hair care products, but the reader’s personal experience had been one of severe allergic reaction. It was a dreadful experience for this person, and it brings to light the unfortunate and unavoidable fact that many of the ingredients used in hair and skin care are potential allergens or irritants. It is not at all uncommon for users to report reactions to seemingly innocuous ingredients that are generally recognized as safe and effective for most people.
Allergies are a highly complex issue of the immune system, and reports seem to be on the rise, although it is difficult to determine whether that is due to increased incidence or increased awareness. One particularly confounding factor in these situations is that an immune system may mount an allergic response after years of repeated exposures to the material, which can be quite baffling and can sometimes lead to an ingredient being overlooked as the source of the problem.