A reservoir for a nebulizer, a nebulizer and a method of filling a reservoir are proposed. To avoid undesirable rises in pressure, a fluid chamber of the reservoir is pre-collapsed and filled with an initial amount of fluid which is less than the maximum volume of the fluid chamber. Preferably, before being filled, the fluid chamber is compressed and/or expanded by means of gas to a defined volume which is less than the maximum volume of the fluid chamber.
