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Jump to Key Points CARLSBAD, Calif. — If a patient turns out to be sensitive to an allergen, should their dermatologist just say, “Here’s what you tested positive to. Stay away from it”?
Absolutely not, dermatologist Brandon Adler, MD, told colleagues here at the fall symposium of the California Society of Dermatology and Dermatologic Surgery.
It is important to provide patients with the resources to navigate the wide world of potential irritants, said Adler, clinical associate professor and director of the Contact Dermatitis Clinic at the University of Southern California, Los Angeles.
Adler offered guidance about allergy misconceptions among physicians and patients. Here are tips from his presentation and a follow-up interview:
- Contact dermatitis counseling should address allergen avoidance resources, not just test results.
- Food + laundry detergents rarely cause allergic skin reactions; modern washing ↓ allergen exposure.
- Sensitization may occur months-years after product use; delayed hypersensitivity causes hours-days rash lag.
- Patch-test positivity requires exposure confirmation + sustained improvement with avoidance; gold/thimerosal often clinically irrelevant.
- Product labels can mislead; “unscented” may contain fragrance, so allergen databases are useful.
Patients May Not Understand True Risks From Detergents and Food
Patients with allergic reactions often have “a lot of fear and misconceptions,” Adler said.
A patient with eyelid dermatitis, for example, might be “worried about something they’re eating, worried about their laundry detergent.”
In fact, food and laundry detergents rarely cause allergic skin reactions, although it’s possible, he said. “It’s been shown that modern washing machines reduce the concentrations of fragrances and allergenic preservatives to concentrations that are so low they shouldn’t be able to cause allergic contact dermatitis.”
Patients Make Wrong Assumptions About Allergy Timing
Another misconception: Patients often think new-onset contact dermatitis is caused by something new in their life. In fact, “there are usually multiple asymptomatic exposures that precede the development of allergy, with the exception of certain stronger allergens that we’re not typically encountering in daily practice.”
He added that “sensitization can occur at any point, even months to years into use of a product. Complicating it further is that once you’re allergic, there’s delayed hypersensitivity. We’re going to have hours, even as long as days, between exposure and rash.”
What’s the best strategy for physicians? “We can explain to the patient that the more times you’re exposed to something, the more opportunities your immune system has to decide that it doesn’t like it,” he said.
Patch Testing Is Helpful — but Only to a Point
Physicians can’t assume they’ve solved an allergic reaction mystery when a patient has a reaction to an allergen in a patch test.
“We need to ideally confirm exposure to that allergen, which is often a challenge,” he said. “Then to really seal the deal, we need to show that there is sustained improvement following consistent avoidance of the allergen.”
As many as 14% of patients who are patch-tested turn out to be positive for gold, but the result is meaningful in less than a third of cases, he said. Patients may also have reactions to the preservative thimerosal, but those reactions are rarely meaningful, he said.
“It’s not in any cosmetics at this point in time,” he said, and “a positive reaction does not mean that the patient has any contraindication to any future vaccines.”
Helping Patients Navigate Potential Allergens
In some cases, patients won’t read labels to determine whether they include ingredients they’re sensitive to. Or if they look at ingredient lists, Adler said, they can be misled or confused.
An “unscented” product, for example, may still have fragrance — a common allergen — that’s included to neutralize odor, he said. Fragrance itself may be described by hundreds of names, he added, and preservatives that release formaldehyde don’t explicitly say so.
Adler said he himself sometimes contacts manufacturers to confirm ingredients in products.
What to do? Instead of telling patients to avoid ingredients, he directs them to resources that list products to avoid. “We need to give the patient a reference that will do the hard lifting for them when it comes to allergen avoidance.”
He recommends the Contact Allergen Management Program from the American Contact Dermatitis Society, a regularly updated database of over 100,000 different products. It designates products as “safe” or “not safe” based on a user’s specific allergens.
“It’s got a great phone app, a barcode scanner, and allergy handouts made by contact dermatitis experts,” Adler said. However, patients can only use it if their healthcare provider is an active member of the society and provides allergen search codes.
SkinSAFE is another useful allergen reference option, he said. SkinSAFE, which offers free and premium levels, says it ranks products “based on how free they are from the topmost common allergy-causing ingredients identified by Mayo Clinic.”
Adler disclosed relationships with AbbVie, Dermavant Sciences, Castle, and UpToDate.
