There has been a significant rise in contact allergy to propolis, a common ingredient in ‘natural’ cosmetics and skincare products, according to dermatologists in Europe.

While nickel and perfumes continue to be the most common contact allergens, the prevalence of contact allergy due to the derivative of beeswax has doubled to almost 4% of patch test results, a survey of dermatology departments in Germany, Austria and Switzerland found.

Among the 125,436 patients patch tested the most common allergens were nickel (14.7%), fragrance mix I (8.1%), Myroxylon pereirae resin (7.5%) and cobalt (5.2%), none of which showed major changes in trends over the previous 12 years

There was a decline in contact allergy to the preservative methylisothiazolinone (MI), reflecting recent EU restrictions on its use in personal care products such as baby wipes.

Propolis contact allergy showed an 80% increase in prevalence from 2.35% of  in 2007-2010 to 3.94% in the period 2015–2018 (prevalence ratio 1.82).

The study authors said the rise in propolis sensitisation was presumably due to the increase in its use as an ‘anti-infective’ ingredient in a range of cosmetics including shampoos, conditioners, ointments, lotions, lipsticks and lip balms, and toothpastes.

“The increase in allergy to propolis that we have observed certainly warrants targeted investigation of what is driving sensitisation,” said Professor Wolfgang Uter, lead author of the study

“At present, we do not know the full extent of its availability and how widely it is used. If the allergy trend continues, we will need to consider a reassessment of risk, and probably risk management such as a limit on the concentration of propolis allowed in products that are left on the skin.”

In the meantime, propolis should be included in patch test baseline series in view of a considerable sensitisation prevalence, they advised.

A spokesperson for the British Association of Dermatologists said propolis is not routinely included in patch testing, so the level of allergies could not be fully established.

Natural skincare products should not be assumed to be safer for the skin than their non-natural counterparts, and patients who have a skin reaction should inform their doctor of all products their skin has been in contact with, they said.

The findings are published in the British Journal of Dermatology.