Poor menstrual hygiene is a significant public health issue, especially among female students in tertiary institutions where academic pressure, limited facilities, and social stigma can worsen hygiene practices. Its impact on reproductive health is both immediate and long-term. Poor hygiene practices (such as prolonged use of one pad or improper cleaning) may alter the natural vaginal pH and encourage growth of harmful bacteria and fungi. This imbalance can lead to conditions like bacterial vaginosis and yeast infections, which affect reproductive health and comfort. This study aimed to Assess Impact of Poor Menstrual Hygiene on Reproductive Health among Female Students in Tertiary Institutions in South-South, Nigeria. This was a cross-sectional study involving 250 women. Participants’ age is between 18 to 47 years. A well-structured questionnaire was administered to participants. The study lasted for a period of 3 months. Statistical analysis was done using SPSS version 25.0 and p < 0.05 was significant. The results revealed that 60% of the participants were university students, 76% have no knowledge about menstrual hygiene, 60% changed change sanitary pad when it is completely soaked, 60% never washed before and after changing menstrual pad, 60% uses tissue materials as pad, 60% do not have access to clean water and toilet facilities during menstruation, 40% disposed used pads in open dumping, 60% are not comfortable during menstruation within school environment. The participants also experienced the following after poor menstrual hygiene including vaginal discharge, bacterial infection, PID, UTI, vaginitis and others, 76% have missed classes due to menstrual discomfort or hygiene challenges.