The duration for the treatment of thrush to be effective indeed varies among individuals, as the development of thrush is sometimes due to inadequate hygiene, or the caregiver might have a fungal infection, and sometimes it is due to a weakened immune system,

Therefore, if these factors are not involved and it's simply a case of thrush, generally, after undergoing treatment such as rinsing with baking soda water or using antifungal medications, the condition should improve within 3 to 7 days. If there is no improvement, it's important to investigate the reasons why the child's condition is persistently poor and address these reasons accordingly. Thus, in most cases, the condition should improve within 3 to 7 days. However, if it does not improve, it is advisable to consult a hospital for a check-up and further treatment.