Eczema sufferers should use oil-based treatments rather than moisturising creams to soothe the condition, according to scientists.
Researchers at Bath University claim using some well-known high street moisturisers could further irritate the skin.
During a study at the university, healthy volunteers applied aqueous cream BP - the most commonly prescribed treatment for dry skin conditions - to their forearms daily for a month.
The cream is used to moisturise the skin, improve flexibility and prevent cracking in the protective outer layer, called the stratum corneum.
However, it contains a detergent, called sodium lauryl sulphate (SLS), which can increase the permeability of the skin barrier and cause irritation.
The study found that when healthy volunteers applied the cream to their forearms daily for a period of four weeks, the thickness of the stratum corneum was reduced by more than 10%.
The researchers anticipate that using this cream would have an even more dramatic effect on damaged skin such as that found in eczema.
Postgraduate researcher, Manda Tsang, who worked on the project as part of her PhD studies, 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 research has been published in the British Journal of Dermatology.