14 DAY TRIAL // A new research carried out at the University of Bath's Department of Pharmacy & Pharmacology, suggests that some emollient creams used for treating eczema can actually worsen the symptoms.
The researchers have focused on the aqueous cream BP and discovered that it reduces the thickness of healthy skin over four-weeks-time, thus questioning whether the product should be used for treating eczema or not.
Aqueous cream BP was normally used as a wash product and has become the most widely prescribed emollient against dry skin.
It moisturizes the skin, it confers flexibility and prevents cracking in the protective outer layer (stratum corneum).
The problem is that it also contains a detergent – sodium lauryl sulphate (SLS), that rises the permeability of the skin barrier and it causes irritation.
The researchers tested the cream of healthy volunteers and observed that after four weeks of use, the thickness of the protective outer layer had decreased by over ten percent.
They concluded that the effects would be catastrophic of people with eczema.
“Eczema affects around 30 per cent of the population, an increase from around five per cent a generation ago,” said postgraduate researcher Manda Tsang, who worked on the project for her PhD CASE studentship funded by the Biotechnology & Biological Sciences Research Council with York Pharma Plc.
“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.”
Richard Guy, Professor of Pharmaceutical Sciences at the University and Project Supervisor, explains: “the skin has a protective barrier layer of lipids, around one eighth the thickness of a sheet of paper, that stops chemicals from getting into the body and keeps moisture in.
“SLS is a detergent used to mix oils into water-based moisturisation creams to give a nice creamy texture.
“It’s also used widely in shower gels and other cosmetics.
“Our study has found that rubbing aqueous cream containing SLS into the skin thins this protective barrier, making the skin more susceptible to irritation by chemicals.
“So to use this cream on eczemous skin, which is already thin and vulnerable to irritation, is likely to make the condition even worse.”
The findings are published in the British Journal of Dermatology.