Your toothbrush will eventually wear out, especially if you are brushing your teeth twice a day for two to three minutes each time. Your dentist recommends that adults and children change their toothbrush every three months. If you are using an electric toothbrush, be sure to read the directions because you may not need to change toothbrush heads as frequently. Patients with gum disease are encouraged to change their toothbrush every four to six weeks to keep any bacteria from spreading. After brushing, rinse your toothbrush with hot water to kill germs and keep the bristles clean. If you've been sick, be sure to change your toothbrush as soon as possible.