Metronidazole belongs to the nitroimidazole group of antibiotics. It is used for the treatment of anaerobic and protozoal organisms. Its common side effects are nausea, vomiting, headache, and abdominal pain. Urine discolouration is one of the rare side effects of metronidazole. We report a case of 4-years-old male, a known case of Steroid resistant nephrotic syndrome; Focal Segmental Glomerulosclerosis type who developed reddish discolouration of urine following the introduction of oral metronidazole which reverted back to its usual colour within 24 hours of discontinuing metronidazole. With no evidence of other possible causes, urine discolouration was linked with the use of metronidazole. Urine discoloration as a side effect of metronidazole is rarely reported in the literature. This case report of the rare adverse effects of the commonly used drug can be of importance in the scientific community. Urine discolouration could be considered a side effect of metronidazole when there is no other obvious cause.