The question of whether mouthwash dilutions, recommended by the producers, contribute to irritation of the oral mucosa was examined. Twenty frequently used mouthwash brands were examined by the pollen tube growth test, an alternative in vitro method for the irritation assessment of ingredients of cosmetic formulations. The test is based on the photometric quantification of pollen tube growth inhibition. This parameter is expressed by IC50 values which characterize the cytotoxic potency of a product. The IC50s clearly revealed that none of the tested mouthwashes should cause acute irritation if used at the recommended dilution. However, 4 to 5 of the mouthwashes could probably irritate the oral mucosa acutely, when used in the form of the original producer concentrations.
