Emulsifying ointment is a mixture of paraffin oils. It is a greasy moisturiser that provides a layer of oil on the surface of the skin to prevent water evaporating from the skin surface. Dry skin results from lack of water in the outer layer of skin cells known as the stratum corneum. When this layer becomes dehydrated it loses its flexibility and becomes cracked, scaly and sometimes itchy.
The stratum corneum contains natural water-holding substances that retain water seeping up from the deeper layers of the skin. Water is also normally retained in the stratum corneum by a surface film of natural oil (sebum) and broken-down skin cells, which slow down evaporation of water from the skin surface. The skin dries out when too much water evaporates from its surface. This increases as we get older and is made worse by washing, because hot water and soap remove the layer of natural oil on the skin surface.
Moisturisers such as emulsifying ointment are helpful for very dry skin conditions, particularly eczema and dermatitis, which get worse when the skin is allowed to dry out. Used regularly they help restore the skin's smoothness, softness and flexibility by helping the skin retain moisture. They should be applied frequently to prevent the skin drying out. Emulsifying ointment can also be used in place of soap when washing to prevent drying the skin. In conditions such as eczema, using a moisturiser regularly, even once the skin has improved, can help prevent flare-ups of this condition.