Menstrual fluid in itself doesn't smell bad. When it comes in contact with air then over time it develops microbes and start emitting a foul smell. Maintaining proper hygiene during periods like taking shower or bath regularly, changing pads or tampons regularly every 3-6 hours and keeping the groin region clean can easily reduce any bad smell.
Sometimes it is just that the girl or woman who is menstruating is very sensitive to her smell while others can't make out.
If the bad smell is present even when you are not menstruating, then it might be an indication of infection. In such a case it is best to visit your doctor who can diagnose your infection and prescribe you the necessary medication. If the doctor prescribes antibiotics then it is recommended to complete the course of the antibiotic as not doing so can cause the infection to reoccur which might require a longer course of even stronger antibiotics to cure it.
answered Sep 30 '13 at 09:35