Formulary
Ferrous Sulfate: Uses, Dosing, Side Effects and Indian Brand Names
Ferrous sulfate is the standard oral treatment for iron deficiency anaemia, the most common nutritional deficiency globally and in India. It provides elemental iron absorbed via DMT1 in the duodenum and must be taken for 3-6 months after haemoglobin normalisation to replenish stores.
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Ferrous Sulfate: Uses, Dosing, Side Effects and Indian Brand Names
Ferrous sulfate is the standard oral treatment for iron deficiency anaemia, the most common nutritional deficiency globally and in India. It provides elemental iron absorbed via DMT1 in the duodenum and must be taken for 3-6 months after haemoglobin normalisation to replenish stores.
NEET PG High-Yield: Ferrous (Fe2+) is better absorbed than ferric (Fe3+). Vitamin C enhances absorption; tea/coffee/calcium inhibit it. Desferrioxamine (deferoxamine) is the antidote for iron poisoning. Reticulocyte response begins at day 5-7 (earliest marker of response to therapy). Continue iron for 3-6 months AFTER Hb normalises (to replete stores). Serum ferritin is the most sensitive indicator of iron stores.
Clinical overview
Ferrous sulfate is the most widely used oral iron preparation globally and is the treatment of choice for iron deficiency anaemia (IDA), the most common nutritional deficiency worldwide. In India, iron deficiency anaemia is a major public health problem, affecting approximately 50% of pregnant women and 58% of children aged 6-59 months (NFHS-5 data). The Indian government's Anaemia Mukt Bharat programme provides free iron-folic acid (IFA) tablets through the public health system. Each 200 mg ferrous sulfate tablet contains approximately 60 mg of elemental iron. The standard therapeutic dose for IDA is 3-6 mg/kg/day of elemental iron in divided doses. GI side effects (nausea, epigastric pain, constipation, black stools) are the major compliance barrier and are dose-related. Taking iron on an empty stomach maximises absorption but increases GI side effects; taking it with meals reduces side effects but decreases absorption by 40-50%. Vitamin C (ascorbic acid) enhances iron absorption by reducing Fe3+ to Fe2+ and chelating iron in a soluble complex. Conversely, tea, coffee, calcium, antacids, and phytates (in cereals and legumes) inhibit iron absorption. The reticulocyte count begins to rise after 5-7 days of therapy, and haemoglobin should increase by 1-2 g/dL after 3-4 weeks. Iron therapy should be continued for 3-6 months AFTER haemoglobin normalisation to replenish body stores. Parenteral iron (IV iron sucrose, ferric carboxymaltose) is reserved for malabsorption, intolerance, or severe anaemia requiring rapid correction.
Pharmacological class
Ferrous Sulfate belongs to the Iron supplement (haematinic, ferrous iron salt) class. Ferrous sulfate provides elemental iron (ferrous, Fe2+) that is absorbed primarily in the duodenum and upper jejunum via the divalent metal transporter-1 (DMT1) on the apical surface of enterocytes. Inside the enterocyte, iron is either stored as ferritin or exported to the plasma via ferroportin on the basolateral surface. In the plasma, ferric iron (Fe3+) binds to transferrin for transport to the bone marrow, where it is incorporated into haemoglobin in developing erythrocytes. Iron is also essential for myoglobin, cytochrome enzymes, and numerous iron-sulfur cluster proteins.
Indian brand names and formulations
Available as: Fefol (GlaxoSmithKline), Autrin (Wyeth/Pfizer), Orofer (Emcure), Tonoferon (East India Pharmaceuticals).
Tablets: ferrous sulfate 200 mg (60 mg elemental iron), often combined with folic acid (IFA tablets). Oral drops: ferrous sulfate 75 mg/0.6 mL (for infants). Oral syrup: ferrous sulfate 150 mg/5 mL. Extended-release tablets: 525 mg (105 mg elemental iron). Parenteral iron (IV iron sucrose, ferric carboxymaltose) for IV use.
Regulatory status
Ferrous Sulfate is classified under OTC (Over the Counter) in India under the Drugs and Cosmetics Act, 1940. Available over the counter. Also distributed free through the Anaemia Mukt Bharat programme (IFA tablets: ferrous sulfate + folic acid). Iron poisoning in children is a medical emergency -- keep out of reach of children.
Indications
- Iron deficiency anaemia (treatment of choice)
- Prophylaxis of iron deficiency in pregnancy (universal IFA supplementation per Indian guidelines)
- Iron supplementation in infants, children, and adolescents in endemic areas
- Chronic blood loss (menorrhagia, hookworm infestation, GI bleeding)
- Post-gastrectomy iron deficiency
Dosing
IDA (adults): 200 mg ferrous sulfate (60 mg elemental iron) TDS, preferably on an empty stomach. Alternatively, newer evidence supports alternate-day dosing for better absorption (due to hepcidin regulation). Prophylaxis in pregnancy: 100 mg elemental iron + 500 mcg folic acid daily (per Government of India IFA programme). Children: 3-6 mg/kg/day elemental iron in 2-3 divided doses. Continue for 3-6 months after Hb normalisation. Take with vitamin C (orange juice) to enhance absorption. Avoid tea, coffee, milk within 2 hours of dosing.
Contraindications
- Haemochromatosis or haemosiderosis
- Haemolytic anaemia (iron is not deficient; supplementation causes iron overload)
- Repeated blood transfusions (secondary iron overload)
- Active peptic ulcer disease (iron irritates GI mucosa)
- Iron accumulation disorders (thalassaemia major on regular transfusions)
Adverse effects
- GI side effects (most common compliance barrier): nausea, epigastric pain, constipation, diarrhoea
- Black stools (iron oxidation -- harmless but may be confused with melaena)
- Metallic taste
- Staining of teeth (liquid preparations -- use straw, dilute with water)
- Iron poisoning in children (accidental ingestion -- medical emergency: GI haemorrhage, metabolic acidosis, hepatic failure)
- Haemosiderosis with chronic excessive supplementation
Drug interactions
- Tetracyclines and quinolones -- iron chelates these antibiotics, reducing absorption of both (separate by 2-3 hours)
- Antacids, PPIs, H2 blockers -- reduce iron absorption by increasing gastric pH
- Calcium supplements and dairy -- reduce iron absorption (separate by 2 hours)
- Levodopa and levothyroxine -- iron reduces their absorption (separate by 2 hours)
- Tea, coffee (tannins) -- chelate iron, reducing absorption by 60-70%
- Vitamin C (ascorbic acid) -- enhances iron absorption (take together)
Pregnancy and lactation
Category A. Iron supplementation is universally recommended in pregnancy in India (per WHO and Government of India guidelines). Iron deficiency anaemia in pregnancy increases risks of preterm delivery, low birth weight, postpartum haemorrhage, and maternal mortality. Universal IFA (iron + folic acid) supplementation is provided free of charge through antenatal services. Dose: 100 mg elemental iron + 500 mcg folic acid daily from the second trimester onwards (first trimester: folic acid alone if nausea is severe).
Exam-style clinical scenario
A 2-year-old child is brought to the emergency department after accidentally ingesting 20 ferrous sulfate tablets belonging to his pregnant mother. He presents with vomiting, bloody diarrhoea, and lethargy 3 hours after ingestion. What is the management? Answer: This is acute iron poisoning, a paediatric emergency. The five stages are: (1) GI toxicity (0-6 hours: vomiting, diarrhoea, GI haemorrhage), (2) Apparent recovery (6-24 hours: deceptive improvement), (3) Systemic toxicity (12-48 hours: metabolic acidosis, hepatic failure, shock), (4) Hepatic failure (2-3 days), (5) GI scarring (2-8 weeks). Management: IV desferrioxamine (deferoxamine) -- the specific iron chelator -- at 15 mg/kg/hour. Whole bowel irrigation with polyethylene glycol. Serum iron level >500 mcg/dL indicates severe poisoning. Abdominal X-ray may show radiopaque tablets.
Cost in India
INR 10-30 per strip of 10 tablets (200 mg); IFA tablets distributed FREE through government programmes
Clinical governance
Author: MedNext Editorial Team. Clinical reviewer: Awaiting clinical review. Jurisdiction: India (Drugs and Cosmetics Act, 1940). Sources: CIMS India, Indian Pharmacopoeia. Publication state: Awaiting clinical review. Correction: Report errors at support@mednext.academy.
Frequently Asked Questions
Why does alternate-day iron dosing work as well as daily dosing?
Oral iron absorption triggers hepcidin release from the liver. Hepcidin degrades ferroportin on enterocytes, blocking iron export into plasma for approximately 24 hours. Taking iron the next day results in poor absorption due to elevated hepcidin levels. Alternate-day dosing allows hepcidin levels to fall, restoring ferroportin-mediated iron export and improving fractional iron absorption. Studies show that alternate-day dosing achieves similar haemoglobin response with fewer GI side effects.
How do you differentiate black stools from iron therapy vs melaena?
Iron-induced black stools are uniformly dark (greenish-black), formed, and not sticky or tarry. Melaena from upper GI bleeding produces black, tarry, sticky, foul-smelling stools (due to digested blood). A faecal occult blood test will be positive in melaena but may give a false positive with iron therapy (iron itself can cause a positive guaiac test). If melaena is suspected, the stool appearance, clinical context, and haemoglobin trend should guide the assessment.
Why is serum ferritin the best indicator of iron stores?
Serum ferritin directly reflects total body iron stores (1 mcg/L of serum ferritin corresponds to approximately 8-10 mg of stored iron). It is the first laboratory marker to fall in iron deficiency (before serum iron, TIBC, or haemoglobin change). A serum ferritin <15 mcg/L is diagnostic of iron deficiency in adults. However, ferritin is also an acute-phase reactant and may be falsely elevated in infection, inflammation, liver disease, and malignancy, masking true iron deficiency. In these settings, a ferritin <100 mcg/L with transferrin saturation <20% suggests iron deficiency.
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