


Consultant Psychiatrist


Understanding how moisturizers work means they can be used effectively.

Last week there was a flurry of interest stirred up by the publication of the results of an experiment investigating the function of the “prune” effect on skin caused by having a long, hot bath. The skin of the hands and feet especially puckers up, and the suggestion is that this helps us, for example, getting a grip on the porcelain as we get out of the bath.

Previously it was thought the skin wrinkles because in a hot bath water soaks into the skin, swelling it up. If this were so, the volume of the skin would increase. However, measurements have shown that the volume decreases – just as it does when a grape becomes a raisin.

It has also known that when nerves to the skin are damaged, wrinkling does not happen. It seems when water passes into the skin from outside, the nerves constrict the skin blood vessels, reducing the volume of the skin. The surface layers then pucker up.This may help when the going gets wet.

No mention so far about moisturizers…

Part of natural skin waterproofing is provided by a surface layer of natural grease called sebum. Without this, water may pass out through the skin too quickly, leaving the skin dry. Bathing, especially washing with soap, both removes sebum, and also loosens the cement between the surface cells of the skin. These effects are a potential problem if you have atopic eczema, as dry itchy skin can be the result. To prevent this from happening, when washing it is recommended soap is avoided. Instead, the correct use of a moisturizer, both before and after bathing, and as a soap substitute, achieves the best results. Moisturizers work by slowing down the loss of water.

Do take care though. Without the wrinkling, getting out of the bath may become a slippery business.

Much, much more on The Combined Approach to atopic eczema at


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