Highlighted below are the common and rare adverse effects of metronidazole: COMMON SIDE EFFECTS - headache - nausea - vomiting - diarrhea - metallic taste in the mouth - constipation RARE ADVERSE EFFECTS - sore throat - burning micturition - abdominal pain - seizures - mood alterations - vision changes - pain in the eye - yeast infection - allergic reactions - dyspnea - rashes and itch Reference: https://www.webmd.com/drugs/2/drug-6426/metronidazole-oral/details#:~:text=Dizziness%2C%20headache%2C%20stomach%20upset%2C,to%20turn%20darker%20in%20color. Image via: https://www.sciencephoto.com/media/281347/view/metronidazole-antibiotic-pills