Dr. Hanif warmly Welcomes you! Thanks for consulting at my virtual clinic. I have carefully worked through your case, and I can realize your health worries. Being your physician, I assure you not to worry as I will take care all of your medical concerns.   Metronidazole causes metorrhagia ( bleeding from uterus, at irregular intervals), dysmenorrhea (painful bleed), vaginal dryness all in different women with different frequency. It is not well documented that metronidazole causes delayed periods. Yes, its possible that the infection you already had, for which you took metronidazole, that has caused some delay in periods. Other causes may be psychological disturbance, hormonal imbalance, just to list some. Don t worry, its not that bad if it is resolved soon. But, if takes more than a couple of added days from now, please consult your Gynaecologist to rule out Pelvic Inflammatory Disease (PID). Hope it helps. If you need further, detailed and quick assistance related to any health issues, feel free to ask me a question directly from my profile. Have a wonderful time ahead. Please don t forget to give five star rating, to help me assist you always in a better way. Click on thanks if you find this answer helpful. Please, write a review on my profile, about your experience with me.   Best Regards! DR. MUHAMMAD M. HANIF USA