-For safety and hygiene purposes it's recommended that you replace the spouts after 1-2 months of use or whenever they start to show signs of wear. -Prior to sterilisation it's recommended using the NUK Baby Bottle Cleanser, it’s natural formula removes dried on milk protein, pulp and juice residues more effectively than hot soapy water alone.- To sterilise cups and spouts it's recommended to use steam, cold water sterilisation or a NUK Steam or Microwave Steriliser. -It's recommended not to use a dishwasher for sterilisation as this can cause material damage.