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Parenteral iron products - fetal bradycardia and Kounis syndrome

27 July 2021

Health professionals are advised that the Product Information (PI) documents for parenteral iron products are currently being updated to include information about fetal bradycardia and Kounis syndrome.

There are four parenteral iron products marketed in Australia. They are ferric carboxymaltose (brand name Ferinject), iron polymaltose (Ferrosig injection), ferric derisomaltose (Monofer) and iron sucrose (Venofer).

Ferric carboxymaltose and ferric derisomaltose are indicated for iron deficiency where oral administration is ineffective or contraindicated; or where there is a need to deliver iron rapidly.

Iron polymaltose is indicated for the treatment of iron deficiency anaemia when oral iron therapy is contraindicated, enteric absorption of iron is defective, or when patient non-compliance or persistent gastrointestinal intolerance makes oral therapy impractical.

Iron sucrose is indicated for the treatment of iron deficiency anaemia in patients undergoing chronic haemodialysis and who are receiving supplemental erythropoietin therapy.

The Therapeutic Goods Administration (TGA) has implemented a class-wide labelling update to include fetal bradycardia and Kounis syndrome in the PI documents of these products in the 'Special Warnings and Precautions', 'Fertility, Pregnancy and Lactation' and 'Adverse Effects' sections.

Hypersensitivity is a class effect that is well documented in the PI documents of all parenteral iron products. Fetal bradycardia and Kounis syndrome are biologically plausible as a result of hypersensitivity reactions.

The maternal oxygenation may be compromised during a hypersensitivity reaction to parenteral iron, which may lead to fetal hypoxia and a subsequent compensatory mechanism may result in fetal bradycardia.

The possible biological mechanism contributing to Kounis syndrome may be based on generation of free metal ions, such as iron, leading to the creation of hydroxyl radicals that can inhibit the synthesis of prostacyclin that influence muscle tone.

Both conditions can have serious clinical implications.

The TGA has implemented these changes to ensure consistent inclusion of safety information to all parenteral iron products marketed in Australia.

What to report? You don't need to be certain, just suspicious!

The TGA encourages the reporting of all suspected adverse reactions to medicines, including vaccines, over-the-counter medicines, herbal, traditional or alternative remedies.

We particularly request reports of:

  • all suspected reactions to new medicines (look for the Black Triangle in PI and CMI documents - this symbol identifies medicines that are new or being used differently)
  • all suspected medicines interactions
  • suspected reactions causing death, admission to hospital or prolongation of hospitalisation, increased investigations or treatment, or birth defects.

Reports may be submitted:

For more information about reporting, visit or contact the TGA's Pharmacovigilance and Special Access Branch


Medicines Safety Update is aimed at health professionals. It is intended to provide practical information to health professionals on medicine safety, including emerging safety issues. The information in Medicines Safety Update is necessarily general and is not intended to be a substitute for a health professional's judgment in each case, taking into account the individual circumstances of their patients. Reasonable care has been taken to ensure that the information is accurate and complete at the time of publication. The Australian Government gives no warranty that the information in this document is accurate or complete, and shall not be liable for any loss whatsoever due to negligence or otherwise arising from the use of or reliance on this document.

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Medicines Safety Update is written by staff from the Pharmacovigilance and Special Access Branch.

Editor: Dr Catherine Brogan

Deputy Editor: Mr Michael Pittman

Contributor: Mr Gilbert Yeap