D3.315 - Airborne allergic contact dermatitis to dry shampoo

Case report: A 58-year-old female patient complained of recurrent swelling, erythema, scaling and itching on the facial skin, especially periorbital. Topical corticoids cleared the skin, and brought short-term relief. Patch testing showed a delayed-type hypersensitivity to cinnamon alcohol. This substance was indicated on the  label of the dry shampoo used by the patient. Avoiding the allergen led to the cure.

Background: The first product resembling a dry shampoo was introduced into the German market in 1908. The main component is starch from potatoes or corn. It is supposed to absorb sebum on the hairy scalp to make the hairstyle appear fresh. It is usually applied as a spray. Excess powder should be brushed out after use. Conventional hair care is time-consuming, especially for long hairstyles. The use of a dry shampoo promises an attractive appearance with gray hair coverage while saving time and money. The target group includes working women. In 2021, Phoebe Nevell, PTA in Chicago listed 30 potential contact allergens in dry shampoos. She expected the publication of case reports in the near future.

Conclusion: Dry shampoos are not an alternative to conventional hair washing due to their high potential for contact allergies and should only be used for a short time. The exposure time of a leave-on product - such as dry shampoo - is longer than that of a rinse-off product - such as a conventional hair detergent. In addition, the concentration of fragrance and preservatives in dry shampoos is much higher than in conventional shampoos.