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Date of issue: October 2023, Version: 1.3

Prussian blue is a dark blue complex pigment used in manufacturing processes, as a laboratory staining agent, and in the treatment of poisoning with radioactive caesium or heavy metals such as thallium.

As with all chemicals, unnecessary exposure to Prussian blue should be avoided in pregnancy. However, where occupational exposure is unavoidable then precautions should be taken to ensure that exposure is minimised and not associated with toxic symptoms.

Data regarding the use of Prussian blue during pregnancy are limited; however, the risks to both the mother and the fetus from untreated radioactive caesium or thallium poisoning are likely to be greater than the unknown risks associated with the antidotal therapy. Prussian blue is not absorbed from the gastrointestinal tract, therefore direct toxic effects to the fetus are unlikely. If required, Prussian blue should not be withheld on account of pregnancy. Discussion with UKTIS is recommended in all cases where treatment with Prussian blue is being considered.

Inadvertent exposure to Prussian blue at any stage in pregnancy would not usually be regarded as medical grounds for any additional fetal monitoring. Where exposure to Prussian blue has occurred for the treatment of poisoning with radioactive caesium or thallium, enhanced fetal monitoring (including monitoring of fetal growth) is likely to be warranted. Discussion with UKTIS is recommended.

This is a summary of the full UKTIS monograph for health care professionals and should not be used in isolation. The full UKTIS monograph and access to any hyperlinked related documents is available to NHS health care professionals who are logged in.

If you have a patient with exposure to a drug or chemical and require assistance in making a patient-specific risk assessment, please telephone UKTIS on 0344 892 0909 to discuss the case with a teratology specialist.

If you would like to report a pregnancy to UKTIS please click here to download our pregnancy reporting form. Please encourage all women to complete an online reporting form.

Disclaimer: Every effort has been made to ensure that this monograph was accurate and up-to-date at the time of writing, however it cannot cover every eventuality and the information providers cannot be held responsible for any adverse outcomes of the measures recommended. The final decision regarding which treatment is used for an individual patient remains the clinical responsibility of the prescriber. This material may be freely reproduced for education and not for profit purposes within the UK National Health Service, however no linking to this website or reproduction by or for commercial organisations is permitted without the express written permission of this service. This document is regularly reviewed and updated. Only use UKTIS monographs downloaded directly from to ensure you are using the most up-to-date version.