The source of poop’s metallic smell is likely iron (via My Crohns and Colitis Team). While excess consumption of iron — such as through supplementation — may be the cause, iron is also naturally found in our blood. Therefore, if you notice blood in your stool after a bowel movement, it likely means that it’s the scent of the iron your nose is picking up on. This bleeding may be the result of hemorrhoids, or bulging veins that develop on the inside of the rectum or around the anus. Hemorrhoids are not unusual, with symptoms affecting approximately 1 in every 20 people in the U.S., reports the Cleveland Clinic. Rectal bleeding is one of the more common symptoms.

Alternatively, metal-scented stool may be caused by bleeding from anal fissures, or minor tears in the anal tissue, explains the Mayo Clinic. Pushing too hard while going number two can produce anal fissures, and you may subsequently notice blood in the toilet or on used toilet paper. In more serious cases, waste that smells like metal could be indicative of a health condition known as diverticulitis, characterized by the development of inflamed or infected pockets in one’s intestines.