Moisturisers in cosmetic applications are ingredients that are added to formulations to increase skin hydration, moisten it, improve its visual characteristics, replenish its water content, and restore any changes in the epidermal barrier. Moisturising creams are used to counter skin dryness, smooth, reduce fine lines, itching, burning, tingling and to achieve the much desired 'anti-ageing' effect.

Generally speaking, they can be: natural, chemical. In particular: botanical anti-inflammatories or exfoliants, vitamins, peptides, botanical antioxidants, skin-lightening agents.

In cosmetics, emollients and moisturisers are often considered synonyms even in the presence of humectants and occlusives.

The best moisturisers are the natural ingredients that exploit the mechanism of integration between the ingredient and the skin by moisturising the horny hydrolipid film, i.e. the thin protective layer that covers the epidermis protecting it from harmful external microbes, keeping the skin moisturised and supple and its pH or acidity value between 4 and 6 (1). 

Then there are the occlusive moisturisers, generally derived from petroleum (Paraffinum, Paraffinum liquidum and others), but also triglycerides, lanolin oil, natural or synthetic waxes, fatty acid esters and others that create an artificial occlusive layer on the stratum corneum of the skin with the advantage of accelerating the protective process but with the disadvantage of preventing the skin's natural transpiration.

Medical 

Moisturisers (emollients) applied in creams can prevent or delay the onset of atopic dermatitis and allergies (2) by supplying the skin with exogenous lipids that improve the properties of the corneal barrier and protect against the onset of inflammation.

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Moisturisers , studies

References____________________________________________________________________

(1) Ali SM, Yosipovitch G. Skin pH: from basic science to basic skin care. Acta Derm Venereol. 2013 May;93(3):261-7. doi: 10.2340/00015555-1531.

(2) Simpson EL, Chalmers JR, Hanifin JM, Thomas KS, Cork MJ, McLean WH, Brown SJ, Chen Z, Chen Y, Williams HC. Emollient enhancement of the skin barrier from birth offers effective atopic dermatitis prevention. J Allergy Clin Immunol. 2014 Oct;134(4):818-23. doi: 10.1016/j.jaci.2014.08.005.