Dimethicone is used to treat dry, rough, scaly or itchy skin, and it is a preventive moisturizer for minor skin irritations such as diaper rash, according to WebMD. Dimethicone is an emollient that decreases itching and flaking of the skin and protects the skin from other sources of irritation.
Emollients are substances that soften and moisturize the skin. Since dry skin is caused by a loss of water, emollients trap water in the skin by forming an oily layer on the top of the skin, explains WebMD. Dimethicone is not to be used on any broken skin, and it is best used regularly and after bathing or showering while the skin is still damp.