Taking iron tablets will turn the stool a dark, almost black color (actually dark green). This is normal, and does not mean that the iron tablets are causing intestinal bleeding.

Why does your stool turn black when taking iron?

You may have noticed after taking iron that your stools have turned black or dark green. While your first reaction might be, “Yikes! Something might be wrong,” don't be alarmed. Black or dark stools are a common side effect that may be the harmless result of unabsorbed iron.

Should I stop taking iron if my poop is black?

Iron pills may cause stomach problems, such as heartburn, nausea, diarrhea, constipation, and cramps. Be sure to drink plenty of fluids and eat fruits, vegetables, and fibre each day. Iron pills can change the colour of your stool to a greenish or grayish black. This is normal.