Ferrous Sulfate Side Effects, Before Taking, Overdose & What to Avoid

Ferrous Sulfate is an over-the-counter and prescribed medicinal supplement that is commonly used for replenishing patients with low blood hemoglobin, low RBC count, and iron deficiency. Iron is an essential mineral for the body and is important because of its oxygen binding property; it has a vital role in producing healthy red blood cells.


Ferrous sulfate is used commonly in patients suffering from anemia, and excessive bleeding in people with poor diet and in pregnant women. This iron supplement is consumed orally and is present in the form of film-coated tablets; extended-release 325 mg round red colored tablets, and 220mg liquid suspension.


Side Effects

All medications carry their fair share of unwanted side effects along with their benefits; if you encounter such health-threatening indications, at once contact your medical advisor.

Allergic reactions, though rare, may manifest from ferrous sulfate. Symptoms include:

  • Hives
  • Skin rashes
  • Itchiness
  • Trouble breathing and swallowing
  • Swollen lips and tongue
  • A rough throat

These signs, if not checked, could prove fatal.



Other common adverse side effects include:

  • Digestive issues
  • Stomach pain or cramps
  • Constipation
  • Loss of appetite
  • Dark colored feces
  • Bloody stools
  • Diarrhea
  • Nausea
  • Vomiting

If symptoms are persistent, then they could be extremely problematic. Get medical attention without delay.

Discoloration (darkening) of skin; change in color of urine (dark) or pain in the legs can also occur as serious side effects of ferrous sulfate.


What to Avoid?

Iron absorption works best on an empty stomach; avoid taking it with or right before a meal. These supplements require a proper diet for their functioning. Avoid caffeinated beverages such as sodas, coffee, and tea for at least a few hours after you’ve consumed ferrous sulfate. Foods that contain calcium bind with iron and which means it can’t be absorbed by the body, so avoid such foods temporarily. Antibiotics and antacids should only be taken 2 hours before or after the supplement has been consumed.


How to take?

Take the medication as per your doctor’s orders, and do not tamper with the dosage as it can be dangerous. Take an oral tablet with a glass of water at least 1 to 2 hours before eating anything. Crushing, chewing, and breaking the tablet can release immediate dosage that the body won’t be able to handle. Always take the liquid suspension in a measuring cup or spoon and shake the bottle well to mix the contents.


How does it work?

Iron supplements basically work by recovering iron deficiency in red blood cells; hemoglobin chains inside our RBCs are responsible for carrying oxygen throughout the body from the lungs to the heart. Due to lack of iron in the RBCs, the hemoglobin cannot adequately bind to oxygen atoms, and there’s not enough oxygen inside the body. Ferrous sulfate provides iron for the healthy functioning of RBCs and improves oxygen binding property inside the hemoglobin.



Inform your doctor about any past or current ailments you might have to rule out the possibility of harmful side effects or potential health damage. Using iron supplements can be problematic if you suffer from thalassemia, porphyria, or have regular blood transfusions, or if you have the iron overload syndrome. Ferrous sulfate is not recommended for alcoholics. Make sure your doctor is aware of these issues so he/she can treat you appropriately.

Ferrous sulfate is safe to use for childbearing women as it helps to restore the depleted iron levels in the mother’s body. However, it is a good idea to get your doctors opinion on the degree of its use and safety to prevent the fetus from any undue harm.

Ferrous sulfate does pass into breast milk; mothers who’re nursing infants should consult a medical professional about using iron supplements in this condition just to be on the safe side.

Mixing ferrous sulfate with other vitamins or supplement drugs can lead to interactions and decreased effectiveness of mineral absorption in the body. Examples include antacids, antibiotics, chloramphenicol, Tagamet, methyldopa, penicillamine, etidronate, dimercaprol (an injection used to treat poisoning by arsenic, lead, or mercury), etc. Before you use ferrous sulfate, ensure that your doctor knows about your drug use, so he/she can understand your condition better and provide the right dosage and treatment.