Red Flags
- IDA with weight loss, change in bowel habit, rectal bleeding, dyspepsia, or family history of GI cancer — same-day endoscopy + colonoscopy under cancer pathway[1]
- Severe symptomatic anaemia (Hb <70 g/L with cardiac decompensation, syncope, dyspnoea) — admit; transfuse 1 unit at a time and reassess; IV iron post-stabilisation[1]
- Recurrent IDA despite repletion and no GI source — investigate menorrhagia, coeliac disease, H pylori, malabsorption, urinary loss, parasitic infection[1]
- Severe hypophosphataemia after IV ferric carboxymaltose — check phosphate at 1–2 weeks if symptomatic; replace; switch agent if recurrent[1]
First-line treatment
Interventions
- Identify and treat underlying cause[1]All adult IDA needs aetiology workup; do not just replete iron; coordinate gastroenterology, gynaecology, or other relevant specialty for definitive treatment
- Diet counselling[1]Iron-rich foods (red meat where consumed, dark green leafy vegetables, pulses, fortified cereals); vitamin C with iron meal; avoid tea/coffee within 1 hour of iron tablet; address vegetarian/vegan deficiencies
- Oral iron repletion (first-line)[1]100 mg elemental iron PO daily or alternate-day; alternate-day improves absorption per hepcidin physiology; continue until Hb normalises + 3 months to replenish stores; reassess Hb at 4–6 weeks
- IV iron when oral fails or contraindicated[1]Indications: intolerance, non-response, ongoing blood loss, malabsorption (IBD, post-bariatric, coeliac), pre-operative repletion within 6 weeks, advanced CKD; ferric carboxymaltose convenient single-dose; iron sucrose multi-dose alternative
First-line drug therapy
| Drug | Class | Adult | Paediatric | Notes |
|---|---|---|---|---|
| Ferrous sulphate[1] | Iron salt (oral) | 200 mg PO TDS (60 mg elemental iron each); or alternate-day single dose | Per local protocol | First-line oral iron; widely available, low cost; nausea, constipation common — alternate-day improves tolerance and absorption; iron polymaltose better tolerated alternative |
| Ferrous ascorbate[1] | Iron salt with vitamin C (oral) | 100 mg elemental iron PO BD | — | Indian-market alternative with claimed better absorption due to integrated ascorbic acid; well-tolerated; cost similar to ferrous sulphate |
| Ferric carboxymaltose (IV)[1] | Parenteral iron — high-dose single infusion | 750–1000 mg IV single dose; can repeat at 7 days for total iron deficit (max 2000 mg total) | — | Single-dose convenience; rapid repletion; phosphate decline at 1–2 weeks (rarely symptomatic); hypersensitivity rare |
| Iron sucrose (IV)[1] | Parenteral iron — multi-dose | 200 mg IV per session × 5 sessions to total dose calculated by Ganzoni formula | 1–2 mg/kg per session | Widely available alternative; multiple sessions; lower hypersensitivity than older iron preparations |
| Iron isomaltoside / ferric derisomaltose (IV)[1] | Parenteral iron — high-dose single infusion | Up to 20 mg/kg IV single infusion | — | Single-dose alternative to ferric carboxymaltose; lower phosphate decrement signal; hypersensitivity rare |
Ferrous sulphate[1]
Iron salt (oral)
- Adult
- 200 mg PO TDS (60 mg elemental iron each); or alternate-day single dose
- Paediatric
- Per local protocol
First-line oral iron; widely available, low cost; nausea, constipation common — alternate-day improves tolerance and absorption; iron polymaltose better tolerated alternative
Ferrous ascorbate[1]
Iron salt with vitamin C (oral)
- Adult
- 100 mg elemental iron PO BD
- Paediatric
- —
Indian-market alternative with claimed better absorption due to integrated ascorbic acid; well-tolerated; cost similar to ferrous sulphate
Ferric carboxymaltose (IV)[1]
Parenteral iron — high-dose single infusion
- Adult
- 750–1000 mg IV single dose; can repeat at 7 days for total iron deficit (max 2000 mg total)
- Paediatric
- —
Single-dose convenience; rapid repletion; phosphate decline at 1–2 weeks (rarely symptomatic); hypersensitivity rare
Iron sucrose (IV)[1]
Parenteral iron — multi-dose
- Adult
- 200 mg IV per session × 5 sessions to total dose calculated by Ganzoni formula
- Paediatric
- 1–2 mg/kg per session
Widely available alternative; multiple sessions; lower hypersensitivity than older iron preparations
Iron isomaltoside / ferric derisomaltose (IV)[1]
Parenteral iron — high-dose single infusion
- Adult
- Up to 20 mg/kg IV single infusion
- Paediatric
- —
Single-dose alternative to ferric carboxymaltose; lower phosphate decrement signal; hypersensitivity rare
Safety-net
- Take iron tablet on an empty stomach with vitamin C (orange juice, citrus); avoid tea or coffee within an hour[1]
- Persistent fatigue, breathlessness, or recurrence of anaemia despite iron — return to your clinician for further investigation; do not just take more iron[1]
- Take iron for 3 months after Hb returns to normal — your iron stores need rebuilding even when blood count is fine[1]
Referral criteria
- Suspected GI source in IDA — men >50 or post-menopausal women, weight loss, bowel habit change, family history of GI cancerGastroenterology with endoscopy and colonoscopy under cancer pathway[1]
- Refractory IDA despite repletion or recurrent IDAGastroenterology / haematology for occult source workup[1]
- Heavy menstrual bleeding contributing to IDAGynaecology for AUB workup and tranexamic acid / hormonal therapy[1]
- Severe anaemia with cardiac compromiseEmergency department; transfusion and IV iron[1]
Clinical summary
Diagnosis, oral and intravenous iron repletion, and aetiology workup for iron deficiency anaemia in non-pregnant adults.