The invention relates to stable liquid neurotoxin formulations which are free of animal proteins, comprising a surfactant, an amino acid selected from tryptophan and tyrosine, a buffer comprising sodium, chloride and phosphate ions, which have a pH between 5.5 and 8, and which are stable for 2 months. These compositions are suitable for use in therapy and in particular for administration to a patient to achieve a desired therapeutic or aesthetic effect. The invention also relates to the use of an amino acid selected from tryptophan and tyrosine to protect a proteinaceous neurotoxin from degradation in a liquid composition which is free of animal derived proteins.
