Multiple topical skin products a challenge for dermatitis diagnosis


By Siobhan Calafiore

1 Nov 2023

Skin is becoming increasingly exposed to a larger number and wider variety of topical products daily, making diagnosis of dermatitis more of a challenge, Australian researchers say.

In a review article for JEADV Clinical Practice [link here], dermatological researchers have called for industry to provide further information about products and a more mechanistic understanding of product−product interactions to enable greater insight into multiple product dermatitis and how to manage or prevent it.

They said the overall incidence of irritant dermatitis was difficult to determine, since in most mild or transient cases the patient simply stopped using the product and didn’t report it, and further testing was required to deduce the nature of dermatitis.

The multiple products that consumers used on their skin each day made the task of diagnosing the cause of a contact reaction challenging, especially considering some mild irritants could not be detected in patch testing, the researchers said.

They said hand dermatitis had been reported in 90% of workers using seven or more cleaning products compared to 23% using one to three products, and that a similar trend was likely to be observed for cosmetics, although had not yet been explored.

“Furthermore, not all products identified as irritants will affect everyone in the same way. The finished composition of products is also often held as trade secret (especially for sunscreens not required to disclose inactive agents or for fragrances),” wrote the researchers from the Therapeutics Research Centre at University of South Australia, Adelaide.

Differential diagnosis

They said differential diagnosis of skin reactions should be explored, including allergic contact dermatitis (ACD), photo‐allergic contact dermatitis (PACD), cosmetic intolerance syndrome (CIS) and sensitive skin syndrome (SSS).

“If patch or prick testing is negative, it is possible that the allergen may not be present in the test panel, or alternatively it may lend support for a diagnosis of either SSS or CIS. Sting testing can be performed using 10% lactic acid (typically a solution is applied to the nasolabial fold) to help distinguish these conditions.

“This should be performed before cessation of multiple product use and a rechallenge applied after a two‐week period. If the skin remains sensitive it is likely to be SSS, whereas if it improves it is likely to be CIS.”

The researchers said when it came to product testing there were key limitations to some of the approaches, given the changes in legislation around animal testing.

For example, in vitro approaches did not represent in use situations, lacked complexities of the native skin – such as hair follicles and sweat glands – and could either overestimate or underestimate irritancy by cumulative irritants.

Further, none of the current methods were validated for multiple exposures.

They said further work needed to be done to provide a standardised framework for the way tests were conducted, analysed and interpreted in the context of multiple product exposures. They also said encouraging the publication of information, particularly around harmful ingredients or ingredient combinations, would be important for reducing the problems associated with multiple product dermatitis.

“An important question to consider is where does the need to innovate formulations come to pose harm to consumers and/or patients? This key question requires balancing the benefit‐risk paradigm, (e.g., benefit of cosmetic effect vs. risk of developing skin complications or non-treatment),” they concluded.

“The industry for topical products is continuing to become more valuable, however there should be no compromise to product safety.”

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