*2.1.3 Occludents*

Occludents are lipohilic (lipid-loving) substances that form a protective film on the skin and restrict TEWL, trapping water in the skin's uppermost layers and protecting against moisture loss [42, 46, 47, 53]. The most commonly used occludent, petrolatum or petroleum jelly (a long, aliphatic/straight chain of hydrocarbons) [54], can enter the intercellular space of the SC and become part of its lipid structure to provide internal occlusion of the SC, resulting in an increased barrier to water loss. In this regard, petrolatum is often considered to be the most effective moisturising ingredient for dry skin [42, 46, 47, 53].
