Nicotine solutions usually consist of nicotine diluted in either propylene glycol or glycerin, both common food additives. They also commonly have a variety of different flavorings added. Nicotine solutions sold separately for use in refillable cartridges are commonly referred to as "e-liquid" or "e-juice".
Solution is available in a variety of different flavors and nicotine concentrations. Nicotine concentrations range from high doses (to mimic the content of regular cigarettes) to midrange and low doses. Solutions are also available which contain little or no nicotine.
Some flavor varieties attempt to resemble traditional cigarette types, such as regular tobacco and menthol, and some even attempt to mimic specific cigarette brands, such as Marlboro or Camel. Solutions are also available with other flavorings, such as Cherry, Apple, mint.