A volatile fragrance ingredient extracted from geranium, geraniol is capable of causing sensitivity when applied to the skin. However, the risk of such a reaction has to do with the depth of penetration into the skin, and geraniol does not penetrate the skin easily. As such, while it's not a great ingredient to see on a label if you have sensitive skin, it's not among the most troublesome fragrance ingredients when used in low concentrations. Despite the minor concern, research has shown that geraniol, like many fragrance oil components, can oxidize in the presence of air and cause damage when applied to the skin's surface.