Leaving a tampon in for too long can lead to bacterial growth, which can cause health concerns such as bad or increased vaginal odor, new or unusual vaginal discharge, pelvic pain, and fever. The rule of thumb is to never leave a tampon in for longer than 8 hours, and most experts recommend changing it every 4 to 6 hours to be on the safe side. Leaving a tampon in for too long can increase the risk of developing bacterial vaginosis, which is an imbalance of the normal, healthy bacteria in the vagina. Additionally, leaving a tampon in for too long can cause tiny abrasions when it is removed, which can increase the risk of toxic shock syndrome (TSS) . TSS is a rare but serious bacterial infection that can cause symptoms such as a sudden high fever, low blood pressure, nausea, vomiting, diarrhea, and a sunburn-like rash. It is important to change tampons regularly, avoid using super-absorbent tampons, and wash your hands thoroughly before and after inserting the tampon to reduce the risk of TSS. If you forget to remove a tampon and it becomes compressed at the top of your vagina, it may be uncomfortable to remove, and you should contact your doctor if you are struggling.