It's cold and flu season again and when you're on the mend be sure to change your toothbrush. Normally you should change your toothbrush every three months, but changing it right after a cold will help keep you from getting reinfected. If you just happened to change your brush right before a cold and want to keep using it afterwards - here's a little trick to save some money. Send your brush through the diswasher! It will be nearly as good as new and freshly disinfected.