From the American Academy of Dermatology
SAN FRANCISCO?A list of 10 chemicals identified in a recent study as the most common contact allergens during the past 5 years was presented at the American Academy of Dermatology's 64th Annual Meeting. "We are trying to make sure we are up to date about what new substances are causing allergy," said Mark D. Davis, MD, professor of dermatology, Mayo Clinic, Rochester, Minn.
Dr Davis and colleagues conducted a 69-panel patch test series in 3854 contact allergy patients from January 2001 to December 2005. Overall, 69.1% had a positive reaction to at least 1 agent, and 50.2% reacted positively to ≥2 agents; <1% of patients were allergic to ≥4 substances.
Although nickel still tops the list of allergy-causing substances (Table), with 17.1% of patients having a positive reaction, the incidence of gold allergy has been steadily rising and is now at 13.5%. Dyes often used in clothing have also become a common cause. These emerging trends are important, Dr Davis said. For example, patients allergic to jewelry have traditionally been advised to choose gold rather than nickel items. These data suggest that this may no longer solve the problem for many patients.
He recommends that most patients be referred for patch testing. "Even when an expert dermatologist thinks the allergy is caused by one thing, it is usually something else," he said. "It may appear that the reaction is to a perfume, when in reality it is a particular chemical in the perfume that is also found in a variety of other cosmetic products."
Keep in mind that not all dermatologists perform patch testing, and the majority of those who do use a small panel of 26 common allergens; that does include the most common contact allergens, but some patients may require referral to a research center where a full patch test panel is available.
Also, patients usually only remember some of their allergens or their names. "It is best to relate the chemical to the daily activity involved," Dr Davis said. "Saying ?you are allergic to this chemical found in rubber, and you touch rubber at work' can be a helpful strategy to help patients avoid allergens." ?
He noted that while corticosteroids are the mainstay of therapy for contact allergy, 3% of patients will also be allergic to corticosteroids. "If a patient is not responding to topical treatment, or their condition is becoming worse, allergy to the corticosteroid should be suspected," Dr Davis said.