Troubleshooting How often should I replace my Sanitiser brush head? When you have a Philips Sonicare UV Brush Head Sanitiser, you might wonder if it is still necessary to replace the brush heads every three months. Replace your Philips Sonicare FlexCare brush head regularly The UV Sanitiser does not affect the wear on the bristles of the brush head. We recommend you replace the brush heads every three months regardless of whether you are using the UV Sanitiser or not. Note: although the UV Sanitiser helps to manage germs and sanitises the brush head, it is not a steriliser.