What’s a Carrier Oil and Why Do I Need one? Essential oils are irritants on the skin. Carrier oils are used in conjunction with essential oils in Aromatherapy to dilute essential oils to a safe topical level to protect the skin. Our skin is most receptive to these oils when it is warm and damp. Carrier oils do not moisten the skin themselves. When applied, they block the moisture in in the skin, keeping the skin from drying out. If applying after a shower, our skin is rece