What is glycerol (glycerin)? - The glycerol (or glycerin) found in emollients typically comes from vegetable-based oils. Glycerol is a substance found naturally in the skin where it helps attract and retain water from the deeper skin layers, thereby helping hydrating and moisturising the skin .
Glycerol is widely used in topical products and has been found to support skin recovery after induced chemical irritation. In such case glycerol is shown to immediately increase the water-holding capacity of the skin, which then secondarily promote the recovery of the skin barrier .
+ Despite the widespread use, glycerol is not known as an irritant or to cause sensitisation
+ Glycerol effectively attracts and binds water, and thereby helps hydrating the upper skin layers
What our experts say
HelloSkin’s experts did not find any clinical data on the specific effects of glycerol on people with psoriasis. However, in patients with atopic dermatitis, a glycerol cream compared with a glycerol free placebo was able to hydrate stratum corneum (the outermost layer of the skin) and restore epidermal barrier function during the treatment, when treated twice daily for 4 weeks .
Also in young children (2-6 years) with atopic dermatitis, an emollient with glycerol and paraffin compared to its vehicle improved skin dryness and hydration and the eczema severity after 4 weeks .
Emollients containing glycerol should also contain an occluding ingredient such as soft paraffin to help trap the water in the outer layer of skin (epidermis).
What else does science say?
Maintenance of skin hydration and elasticity in the epidermis has been shown to involve specific water channels that transport both water and glycerol in and between the skin cells. Genetically modified mice without these specific water channels show reduced skin hydration and elasticity, which is corrected after topical or systemic application of glycerol .
This highlights the importance of these channels in healthy skin. Importantly, in psoriatic lesions these water channels are found mislocated in the skin cells, which makes them unable to properly transport water and glycerol . It is therefore likely that the transport through these channels is compromised in the keratinocytes in psoriatic plaques .
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