Ricinus Communis (Castor) Seed Oil

Ricinus communis (castor) seed oil is a vegetable oil derived from the castor bean, which is noted as a rich source of skin-beneficial fatty acids. It is used in skin care formulations as an emollient, though its unique property is that once it dries it forms a solid film that can have water-binding properties. It can also enhance the absorption of other cosmetic ingredients.

Depending on the other ingredients combined with in a formulation, Ricinus communis (castor) seed oil can have a slightly sticky feel on skin. It is known for maintaining its fluidity at extremely high and very low temperatures. Its unique sensory profile makes it popular for use in lip products.

Ricinus communis (castor) seed oil is rarely associated with skin sensitivity and has been deemed safe by the Cosmetic Ingredient Review Expert Panel. Their 2007 report looked at personal care products using up to 81% of Ricinus communis (castor) seed oil.

The unique chemical composition of castor oil makes it a stable vegetable oil and gives it a heavier texture than other vegetable oils.

Despite what you may have heard or read online, there is no substantiated research to prove that castor oil can stimulate hair growth.

Castor oil works primarily through its emollient action. The oil molecules form a thin layer on the skin surface, which helps to seal in moisture and prevent water evaporation. This occlusive mechanism is what gives it its conditioning effect.

In product formulations, castor oil also acts as an emulsion stabiliser, helping to bind water and oil-based ingredients together and create a more stable, consistent texture.

Castor oil works well in both rinse-off and leave-on formulations. In leave-on products, it is typically used at concentrations between 10–100% depending on the product type, though lower percentages (under 20%) are common in lighter serums and essences. It can be used daily as part of a regular skincare routine, though individuals with oily or acne-prone skin may prefer products where it is combined with lighter or mattifying ingredients to balance its occlusive nature.