This is more common than you realize and if you are busy, it is easy to forget about wearing a tampon. When a tampon is left in place for 24 hours or longer, bacteria is allowed to grow and this creates a smell that seems like something is rotting. If you continue to leave the tampon in place, you can actually cause permanent damage that can impact your fertility. In other cases, death is possible due to the high levels of bacteria eventually leading to sepsis. It is important to remove and replace your tampons on a regular basis, even with a light flow.