Method of obtaining a frothy drink from a cartridge, the said cartridge being made up of at least one chamber containing at least a preparation for a drink. The method comprises injecting into the said cartridge a predetermined volume of fluid, a first part of which essentially consists of air which is compressed in the cartridge to a pressure lower than the pressure at which the cartridge opens or the drink flows freely through the said cartridge and a second part of which consists of water, or possibly of a mixture of air and water, which is injected after the first part into the cartridge so as to make it possible to obtain the drink by causing the internal pressure to increase until the cartridge opens or the drink flows freely through the cartridge thus allowing the drink to be discharged and froth to be formed.