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IV Iron — Anaemia Pregnancy: Avoid first trimester; use with caution in second/third trimester — preferred IV iron in pregnancy when oral iron fails

Ferric Carboxymaltose

Brand names: Ferinject

Adult dose

Dose: 500–1000 mg (weight and Hb-dependent per Ganzoni formula or simplified protocol)
Route: IV infusion or slow IV injection
Frequency: Single dose; repeat after minimum 7 days if required (max 1000 mg per session)
Max: 1000 mg per administration; up to 20 mg/kg for patients <50 kg
Preferred IV iron in UK (can be given in 15 minutes as 1000 mg). Used when oral iron is not tolerated, absorbed poorly, or anaemia requires rapid correction (e.g. pre-operatively, IBD, HF, CKD, pregnancy). Monitor for hypophosphataemia.

Paediatric dose

Dose: 15 mg/kg mg/kg
Route: IV infusion
Frequency: Single dose; repeat after 7 days if required
Max: 750 mg per administration
BNFc: children ≥14 years and ≥50 kg — use adult dose. Children <14 years or <50 kg — 15 mg/kg up to 750 mg. Licensed in children ≥1 year.

Dose adjustments

Renal

No dose adjustment required; preferred over oral iron in CKD stage 3b–5

Hepatic

Avoid in decompensated hepatic cirrhosis

Paediatric weight-based calculator

BNFc: children ≥14 years and ≥50 kg — use adult dose. Children <14 years or <50 kg — 15 mg/kg up to 750 mg. Licensed in children ≥1 year.

Clinical pearls

  • Preferred IV iron in UK for speed of administration — 1000 mg can be given in 15 minutes (unlike iron sucrose which requires slower infusion)
  • MHRA: hypophosphataemia is a clinically significant side effect — check phosphate at baseline and 4 weeks post-dose in high-risk patients (renal impairment, malnutrition)
  • Pre-operative IV iron: recommended by NICE NICE QS178 for patients with Hb <130 g/L scheduled for major surgery (patient blood management)
  • Heart failure: IRONOUT-HF and AFFIRM-AHF trials — IV iron improves symptoms and reduces HF hospitalisation in iron-deficient HFrEF
  • Ferritin >800 mcg/L or TSAT >50% — iron overload; do not administer
  • Always have adrenaline and resuscitation equipment available during IV iron infusion

Contraindications

  • Iron overload (haemochromatosis, haemosiderosis)
  • Anaemia not caused by iron deficiency
  • First trimester of pregnancy
  • Hypersensitivity to IV iron preparations

Side effects

  • Hypophosphataemia (up to 75% — usually transient)
  • Flushing
  • Hypotension
  • Nausea
  • Injection site reactions
  • Anaphylaxis (rare — have resuscitation available)
  • Transient arthralgia

Interactions

  • Oral iron — avoid concurrent use (reduces absorption and may increase GI side effects)

Monitoring

  • Hb and ferritin (4–8 weeks post-dose)
  • Serum phosphate
  • Signs of anaphylaxis during infusion

Reference: BNFc; BNF 90; BNFc; MHRA Drug Safety Update (2023) IV iron; AFFIRM-AHF (ESC 2020); NICE QS178. Verify against your local formulary and the latest BNF before prescribing.

Related

Curated clinical cross-links plus same-class fallbacks.

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