Nasal douches are applied in great number of diseases of the nose and the paranasal sinuses. For this purpose, many different kinds of nasal douching systems have been introduced into the market. The aim of this study was to examine the irrigation characteristics of the current nasal douching systems. In this context, 26 nasal douching systems were compared regarding irrigation volume, irrigation duration, flow rate and pressure and course of the irrigation stream. The following procedure was applied: First, the spontaneous flow through the nasal douche was measured, then the flow under compression. Finally, these procedures were repeated using a nose model. Furthermore, we asked the manufacturers for information concerning possible cleaning and disinfection techniques. Douching period and flow rate highly depend on physical parameters: distance between liquid column and outlet (hydrostatic pressure) and form and size of the outlet (energy loss because of friction/turbulence). A weak irrigation stream was found in spontaneous release of the douching system when both douching pressure and flow rate offered low values. The douching of the nose model showed that the incompressible nasal douches only reached the lower nasal passage. Only the compressible nasal douching systems led to a diffuse moisturization as well as to a perfusion of the entire nasal cavity. Systematic evaluation of the different recommended cleaning and disinfection methods of the nasal douching systems is still missing. Nasal douches are often recommended in many diseases of the nose and the paranasal sinuses. In this comparative in vitro study, physical parameters and material properties of the nasal douching systems were examined for the first time. For irrigation of the whole nasal cavity and paranasal sinuses, compressible douching systems are recommended which have a minimum output pressure of 120 mbar, a good connection of the outlet to the nostril with a possible insertion into the nasal vestibule and an irrigation stream which is directed upwards (45°). The material should be transparent, easy to clean and disinfect and should not contain harmful elements.