Iron Deficiency Anaemia in Acute Care

This is an abbreviated version of the full GGC guideline Diagnosis and Treatment of Iron Deficiency Anaemia in Adults.

The guideline does not cover the diagnosis or treatment in the following clinical situations:

Introduction

Iron deficiency anaemia (IDA) occurs in more severe stages of iron deficiency, when the body is iron deficient to the degree that red blood cell and haemoglobin (Hb) production is reduced. The cause of IDA is often multifactorial, and can be broadly attributed to:

• Dietary deficiency
• Malabsorption e.g. coeliac disease, gastrectomy, Helicobacter pylori infection
• Increased loss - chronic blood loss, especially from the uterus or gastrointestinal tract
• Increased requirement
• Other causes e.g. blood donation, self-harm, haematuria, medication.

Assessment and monitoring

For diagnosis of IDA, see flowchart (see page 3 of guideline).

Serum ferritin (SF):

• Most useful test in confirming the diagnosis of IDA;
• A low SF (<45micrograms/L) provides absolute evidence of iron deficiency;
• Can be elevated in inflammatory processes, potentially masking iron deficiency;
• SF >150micrograms/L generally rules out IDA even in the presence of inflammatory disease;
• If the results are equivocal, practitioners could consider checking iron studies, however these should not be considered in isolation.

Drug treatment options

Treatment with iron replacement therapy should be considered for patients with clinically relevant IDA in whom the clinical benefit of treatment outweighs any risk. Investigation and treatment of an underlying cause should prevent further iron loss, but all patients should have iron supplementation both to correct anaemia and replenish body stores.

Oral iron (first-line treatment choice)

Product choice and dosage

Ferrous sulphate 200mg once a day or ferrous fumarate 210mg once a day taken in the fasting state is recommended for initial treatment. Tablets should be taken in the morning on an empty stomach with either water or fresh orange juice to maximise absorption.

If response is poor, consider:

• Non-compliance*- assess and address adverse effects
• Continued blood loss - investigate and treat underlying cause(s)
• Malabsorption
• Wrong diagnosis - re-check ferritin and reassess
• Other complicating factors, in which case reassess treatment.

*If oral iron treatment is not tolerated, adverse effects should be addressed by:

• Reducing the dose frequency to one tablet on alternate days.
• Trying an alternative salt / formulation with a lower content of elemental iron.

Drug interactions

Iron salts are not well absorbed orally, and their absorption is reduced if taken concurrently with certain foods / drugs / supplements such as:

• Milk and dairy products
• Tannins (present in tea, coffee, cocoa, cola)
• Phytates (present in cereal grains, legumes, nuts and seeds)
• Calcium, zinc or magnesium salts (e.g. in antacids or supplements)

Oral iron can reduce the absorption of some drugs if taken concurrently, reducing bioavailability and clinical effect.

Please refer to the BNF and GGC guideline Oral Tetracycline and Fluoroquinolone Antibiotic Interactions with Multivalent Cation Containing Products, Management of for more information on the management of these drug interactions.

Intravenous iron (second-line treatment choice)

IV iron may produce severe adverse effects and should be reserved for patients who meet the inclusion criteria below.

Inclusion criteria

• Genuine intolerance to oral iron preparations. Iron preparations with a low content of elemental iron must be tried before acceptance of genuine intolerance to oral iron.
• Severe IDA and concern regarding the patient's ability to comply with oral iron treatment.
• Patients with clinically active inflammatory bowel disease, with previous intolerance to oral iron, with Hb <100g/L, and in patients who need erythropoiesis-stimulating agents.
• Patients with heart failure with reduced ejection fraction, New York Heart Association (NYHA) class III with a left ventricular ejection fraction (LVEF) ≤45%, or NYHA class II, LVEF ≤40%, who have a Hb level of 95 to 135g/L and iron deficiency (defined as ferritin <100micrograms/L or <300micrograms/L if transferrin saturation (TSAT) <20%).

Exclusion criteria and cautions

Please refer to the full GGC Diagnosis and Treatment of Iron Deficiency Anaemia in Adults guideline to view the full exclusion criteria and cautions before prescribing IV iron.

IV iron therapy should be initiated by a consultant, specialist trainee or equivalent. IV iron should not be administered out of hours or when adequate supervision is unavailable.

Use during infections

IV iron can act as a nutrient source for bacteria which may worsen pre-existing infections. Assess the risk versus benefit of delaying the IV iron infusion if the patient has an infection. Monitor for signs of worsening infection if treatment is given.

Choice of IV iron agent

Monofer^® (ferric derisomaltose) allows for larger doses to be given in a single infusion. This often allows the entire required dose to be given in one infusion. If it requires to be split across two doses, clinical judgement can be used to determine if further laboratory tests could be checked four weeks after the first infusion to assess response.

Feristark^® (ferric carboxymaltose) remains an alternative option when Monofer^® is not suitable. Due to licence restrictions, patients aged 16-17 should receive Feristark^®.

For information on how to prescribe and administer the IV iron preparations as infusions:

• Monofer^® (ferric derisomaltose) see here (see page 9 of guideline).
• Feristark^® (ferric carboxymaltose) see here (see page 10 of guideline).

Note: These guides should be printed for use as prescribing and administration checklists in clinical areas. These can be printed from the links above.

Interaction with oral iron preparations

• Combined treatment with oral and IV iron may lead to the appearance of highly toxic non-transferrin bound iron.
• It is recommended that oral iron preparations are discontinued at least 48 hours prior to IV iron infusions.
• The need for oral iron therapy should be reviewed following IV replacement and generally should not be required.
• If ongoing prophylaxis is deemed necessary, oral iron should not be restarted for at least 5 days after the last IV iron infusion.

Complications

Hypersensitivity reactions

• IV iron preparations can cause rare but serious hypersensitivity reactions.
• Caution is needed with every dose of IV iron that is given, even if previous administrations have been well tolerated.
• The steps outlined in the administration checklists should be taken to monitor patients during and for at least 30 minutes after every administration.
• If hypersensitivity reactions or signs of intolerance occur, the infusion must be stopped immediately and appropriate management initiated as outlined in the full guideline here.

Extravasation

• Paravenous leakage at the infusion site may lead to irritation and potentially permanent brown discolouration at the site of infusion.
• Patients should be informed about the possibility of discolouration and advised to report any signs of irritation or pain at the infusion site immediately.
• The most effective safeguard against extravasation is to visually inspect the infusion site regularly. The steps outlined in the administration checklists should be taken to monitor the infusion site during and for at least 30 minutes following administration.
• In the case of suspected paravenous leakage, treatment requires prompt attention as outlined here.

Communication of treatment

Treatment with IV iron should be clearly communicated to primary care including details of: treatment received, the second dose (if required) and arrangements for follow up blood monitoring.

Assessing response to iron therapy

It takes around 4 weeks for the full effect of either treatment to be reflected in Hb. Hb levels should rise by at least 20g/L.

Guideline reviewed: June 2026

Page last updated: August 2026