After using a thermometer, it is best to wash it so that the next person who is going to use it won't get the flu or illness that the person who used it before. In washing it, it is best to wash it, rinse it thoroughly, sanitized it with the use of alcohol to remove excess germs and bacteria that could be still stuck on it and lastly, air dry. When dried, placed it on its proper case to avoid it from breaking or being contaminated.