In one aspect, the present invention features a method of administering nicotine or a salt thereof to a human, wherein the method includes inhaling an aerosol of a liquid formulation, the liquid formulation comprising: (i) at least 12 percent by weight of water； (ii) at least 70 percent by weight of propylene glycol； and (iii) at least 2 percent by weight of said nicotine or a salt thereof； wherein the liquid formulation includes no more than 5 percent by weight of glycerol and no more than 5 percent by weight of ethanol. The present invention also features an aerosol-generating device and a reservoir for such a device containing such a liquid formulation.
