Ferrous fumarate is a type of iron. You normally get iron from the foods you eat. In your body, iron becomes a part of your hemoglobin and myoglobin. Hemoglobin carries oxygen through your blood to tissues and organs. Myoglobin helps your muscle cells store oxygen.

Ferrous fumarate is used to treat iron deficiency anemia (a lack of red blood cells caused by having too little iron in the body).

However, taking ferrous fumarate also has plenty of side effects as follows:

feeling or being sick (nausea or vomiting), stomach discomfort or heartburn.

loss of appetite.

constipation.

diarrhoea.

dark or black poo.

black stained teeth (from the liquid only)