The invention provides a computer-implemented method (101, 301) for determining treatment data relating to treatment by means of a
personal care device (1, 205). The method involves receiving (103, 303) first sensor data (SD1) generated by a first sensor (13, 215) and relating to a treatment parameter at a first moment of time (t1), and receiving (103, 303) second sensor data (SD2) generated by a second sensor (19, 229) and relating to a treatment condition of the
personal care device with respect a body part subject of the treatment. If, based on the second sensor data, the
personal care device is determined to be in an enabled treatment condition at said first moment of time wherein the treatment is enabled, the treatment data are determined (309) based on the first sensor data relating to the treatment parameter at said first moment of time. The method further involves, by comparing (105, 305) the second sensor data with first predetermined sensor data (PSD1), determining (105, 307) whether the second sensor is in a disabled condition at said first moment of time (t1). If the second sensor is determined to be in the disabled condition at said first moment of time, a predefined data usage rule is used to determine (109, 111, 113; 313) whether to base the treatment data on the first sensor data (SD1) relating to the treatment parameter at said first moment of time.