Iron Supplement (Oral) Pregnancy: Safe and recommended in pregnancy — iron requirements increase significantly in second and third trimester. Routine prophylaxis 200mg OD recommended if Hb <105g/L.

Ferrous Sulphate

Brand names: Ferrograd (200mg), Ironorm Drops, Sytron (ferrous fumarate liquid)

Adult dose

Dose: Iron deficiency anaemia (treatment): 200mg ferrous sulphate (65mg elemental iron) BD–TDS. Prophylaxis in pregnancy: 200mg OD. Target: haemoglobin response of ≥10g/L rise per 2 weeks; treat for 3–6 months to replenish stores.

Route: Oral

Frequency: Two to three times daily (treatment); once daily (prophylaxis)

Max: 600mg daily (200mg TDS)

Take on an empty stomach (30 min before food) for best absorption — food reduces absorption by up to 60%. If GI intolerance, take with food (lower dose frequency if needed). Vitamin C (ascorbic acid) 200mg with each dose enhances absorption. Avoid tea, coffee, milk, or antacids within 2h — reduce absorption. Stools will turn black — warn patient (harmless).

Paediatric dose

Dose: 3 mg/kg

Route: Oral

Frequency: Once to twice daily

Max: 65mg elemental iron OD (older children)

BNFc: 1 month–17 years: 3mg/kg elemental iron OD (Ironorm Drops or sodium feredetate liquid for young children). Ferrous sulphate tablets: 12–17 years: 200mg BD–TDS. Seek specialist paediatric haematology opinion for severe or refractory IDA. (elemental iron)

Dose adjustments

Renal

No dose adjustment required. If severe CKD — consider IV iron (ferric carboxymaltose) as oral absorption may be impaired due to hepcidin elevation.

Hepatic

No dose adjustment required.

Paediatric weight-based calculator

Patient weight (kg)

Clinical pearls

Must identify and treat underlying cause — iron deficiency anaemia is a symptom, not a diagnosis. Investigate for GI bleeding (faecal occult blood, colonoscopy if indicated), malabsorption (coeliac serology), menorrhagia, or poor dietary intake
IV iron (ferric carboxymaltose / Ferinject): preferred when oral iron not tolerated, not absorbed (post-bariatric, coeliac), or when rapid iron repletion is required (pre-surgery, pregnancy third trimester)
Target: Hb rise ≥10g/L per 2 weeks confirms response. Continue for 3 months after Hb normalises to replenish iron stores (ferritin ≥50 micrograms/L)
Alternate-day dosing: emerging evidence that alternate-day dosing (not daily) optimises iron absorption by avoiding hepcidin-mediated suppression — consider for patients with poor GI tolerance

Contraindications

Iron overload conditions (haemochromatosis, haemosiderosis)
Haemolytic anaemia not due to iron deficiency
Repeated blood transfusions
Parenteral iron within 5 days (timing)

Side effects

Constipation, diarrhoea, abdominal pain (very common — dose-related)
Nausea
Black stools (harmless — warn patient)
Tooth staining (liquid preparations — dilute and use straw)
Iron overload (rare with oral preparations in patients without haemochromatosis)

Interactions

Antacids, calcium, magnesium, zinc, milk — reduce iron absorption; separate by 2h
Tetracyclines, quinolones — iron reduces absorption of antibiotic; separate by 2h
Levothyroxine, bisphosphonates — iron reduces absorption; separate by 4h
Proton pump inhibitors — reduce gastric acid, impairing ferric-to-ferrous conversion and absorption

Monitoring

FBC (Hb rise at 2–4 weeks, then 3 monthly)
Ferritin (repletion target >50 micrograms/L)
Reticulocyte count (peak at 7–10 days confirms response)
GI tolerability

Reference: BNFc; BNF 90; NICE NG24 (Anaemia in CKD); BSH Guidelines on Iron Deficiency Anaemia. Verify against your local formulary and the latest BNF before prescribing.

Curated clinical cross-links plus same-class fallbacks.

Calculators

Drugs

Ferrous Sulphate · Iron Supplement (Oral)

Pathways