Get emergency medical help if you have signs of an allergic reaction: hives, blistering or peeling skin; fever; difficulty breathing; swelling of your face, lips, tongue, or throat.
Call your doctor at once if you have:
bright red blood in your stools;
black or tarry stools;
a fever;
stomach pain;
coughing up blood or vomit that looks like coffee grounds; or
pain in your chest or throat when swallowing a ferrous gluconate tablet.
Common side effects may include:
constipation, diarrhea;
nausea, vomiting, stomach pain;
loss of appetite;
green-colored stools; or
temporary staining of the teeth.
This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.
 Ferrous gluconate side effects (more detail)
