Liquid synthetic detergents are more likely to be acidic than other cleansers, making them a better option for people with atopic dermatitis (AD).
This is the main message from a new study presented at the 2024 American Academy of Allergy, Asthma & Immunology Annual Meeting in Washington, DC,
Skin with AD changes pH from acidic to alkaline, which contributes to skin-barrier dysfunction. Acidic cleansers are typically preferred for AD skin care, but information on product pH is scarce.
To explore this topic, researchers collected 250 cleansing products from local retail stores in a medium-sized US city and measured pH of those cleansing products using Accumet pH meter. Solutions were made by dissolving 1mL of liquid product or 1g of bar scrapings in 9mL distilled water, and pH values 6.65 to 7.35 were considered neutral.
Of the 250 cleansing products, 37 were soaps, 32 bar soaps and 5 liquid soaps, and 213 were synthetic detergents (syndets), 14 bar syndets and 199 liquid syndets. All soaps were found to be alkaline, although none of the soap labels disclosed pH levels. In 14 syndet bars, 6 had neutral pH and 8 were alkaline, the study showed. Among the 199 syndet liquids, 84.9% were acidic, 11.1% were neutral and 4% were alkaline. Only 32 syndets, 16.1%, disclosed pH levels. Nine syndet bars were labelled “balanced,” with neutral pH in 6 and alkaline pH in 3. Of the other 23 syndets, the pH was also referred to as “balanced” in 20 with pH measured as neutral in 2, acidic in 18 and “in pH range 4.25 to 6.0” in 3 whose measured pH was actually 4.40 to 6.11.
Only 12.8% of marketed cleansers disclosed pH. The pH of the tested cleansers varied widely among brands, and all tested soaps had an undesirable pH, whereas 84.5% of liquid syndets were acidic and 11% neutral.
These findings suggest that patients with atopic dermatitis may find better results with liquid syndets compared to other skincare options, the researchers conclude.