The present invention provides a refillable container (1) for use with a nebulizer device having an aerosol generator comprising a transducer body and a membrane having pores, the container having an opening being fillable with a cleaning liquid (3), wherein the opening is sized and shaped to fit onto the transducer body, so that the container is held in place on the nebulizer device and the membrane is immersed in the liquid inside the container. The invention also provides a pack comprising a multi-day supply of a drug, one or more cleaning liquids and one or more containers； and a method for cleaning the membrane of a nebulizer device using the container. The immersion of the membrane in the cleaning fluid while it is isolated from the surrounding environment prevents the cleaning fluid from being contaminated
