The simplest treatment of dry skin conditions is with fixed vegetable oils. Many of these vegetable, nut, seed, and kernel oils are simple blends of fatty acids with varying
carbon chain lengths. Coconut, sunflower, safflower, rapeseed, corn, or sesame seed oil will give perfectly acceptable skin coverage and are most often used as carrier oils for essential oils. These oils will coat the skin to occlude and protect it by slowing down transepidermal water loss and so increasing hydration within the stratum corneum and top layers of the dermis. They will also “glue down” dry and desquamatous skin cells to make the skin look less rough and scaly. Some oils such as castor seed oil (Ricinus communis) are renowned not only for their very high gloss (and so a frequent component in lipsticks and lip salves), but also for their high degree of occlusiveness which makes them ideal for skin protection, for example, diaper or nappy rash creams, where the most traditional and best-known example would be zinc and castor oil cream.

Other oils such as evening primrose oil (Oenothera biennis), borage (starflower) seed oil (Borago officinalis), and blackcurrant seed oil (Ribes nigrum) are particularly useful because of their high γ-linolenic acid content. Evening primrose used to hold a pharmaceutical license for use on atopic dermatitis, but subsequently lost this status on the publication of further clinical trial data. It is still widely taken orally for mastitis (breast pain).

A new oil, made commercially available in 2006, is inchi oil (Plukentia volubilis), which also has the name Aztec peanut - although it is totally unrelated to the peanut (Arachis hypogaea). This oil is abundant in omega-3, omega-6, and omega-12 fatty acids, and could well show huge promise in skin care. Another plant that is rich in γ-linolenic acid is a particular species of rose hip seed oil (Rosa aff. rubiginosa) that is collected in the foothills of the Chilean Andes and often called Rosa moschata.

This oil is reputed to contain vitamin A according to some references. A large body of evidence (mainly anecdotal clinical) suggests that this oil has exceptional cicatrizing properties and is an excellent oil for restoring skin elasticity especially for postsurgical conditions where tightness has become a problem for the patient. It was also shown to be effective for treating the hyperpigmentation of certain scar tissues.

Source: Dermatologic, Cosmeceutic and Cosmeticdevelopment - Kenneth A. Walters, Michael S. Roberts

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