Undecylenic Acid (C₁₁H₂₀O₂) is a natural fungistatic fatty acid that inhibits the growth of fungi. This fatty acid can be synthetically processed via the distillation of castor oil. It is used in cream as a zinc salt due to its astringent action. It is used to fight against varied fungal infections and other cutaneous conditions. In addition to this, Undecylenic Acid is also widely used in cosmetics, perfumery, toiletries and other medicinal applications. This is approved by the FDA for topical administration.