The concentration of aromatic compounds determines the fragrance type. Most fragrances are mixed with alcohol or water to dilute them, as pure perfume could be overpowering. Fragrances labeled as simply "perfume" contain the highest concentration of compounds, for a more intense, longer-lasting scent. While compound concentration is not regulated in fragrances, typically eau de parfum contains less than 20%. Some people with sensitive skin prefer fewer aromatic compounds, such as an eau de parfum, or eau de toilette, which usually contains less than 15% perfume oil. Another option is eau de cologne, which usually contains under 5% aromatic compounds.