Normal menstrual blood has a bloody odor, but it usually does not manifest itself as a foul odor. If you notice a change in the smell of menstrual blood with a foul odor, it is recommended that you go for a gynecological examination 3-5 days after the end of your period. A common cause is gynecological inflammation, most likely cervicitis, cervical erosion or endometritis, which leads to bacterial decomposition and produces a foul odor, which manifests itself as foul-smelling vaginal discharge or menstrual blood. Generally need active anti-inflammatory treatment, commonly used antibiotics for metronidazole combined with cephalosporin or penicillin antibiotics, the best choice of oral or intravenous drugs combined with vaginal medication. Specific treatment measures should be based on the results of the examination, the lesion site, to choose effective means of treatment.