People with eczema who use moisturising cream can end up making their condition worse, researchers have reported.
Famous brands bought in high street shops can actually irritate the skin, according to scientists at Bath University.
Eczema should instead be treated with oil-based ointments, they added.
Commonly prescribed aqueous cream BP, for example, was found to significantly reduce the thickness of healthy skin over a four-week period and cause irritation because it contains the detergent sodium lauryl sulphate.
The cream, originally used to wash the skin, is used as a moisturiser to make the skin more flexible and to stop the protective outer layer from cracking.
Healthy volunteers applied aqueous cream to their forearms every day for four weeks. The scientists found that the thickness of the stratum corneum was down by at least 10%, adding that this damage is likely to be more pronounced in people with already unhealthy skin.
Manda Tsang, who worked on the study, said: “Eczema affects around 30% of the population, an increase from around 5% a generation ago.
“This is due to a combination of genetic and environmental factors, such as central heating and carpets that can encourage dust mites, and using more creams and cosmetics that can thin the skin if used too frequently.
“Our study suggests that it might be better for eczema patients to use oil-based ointments on damaged skin.”
The study findings appeared in the British Journal of Dermatology.