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Date of issue: January 2023, Version: 2.0

Dimercaptosuccinic acid (DMSA) is an organosulfur antidote used orally in the treatment of heavy metal poisoning; particularly lead and arsenic.  There are insufficient published data available to provide a risk assessment on the potential effects following exposure to DMSA in pregnancy.  Where maternal toxicity occurs following heavy metal poisoning, there is a potential for fetal toxicity.  In cases of severe maternal systemic poisoning, it is important to treat the mother appropriately to reduce the risks of maternal and fetal toxicity.

The antidotes used in the treatment of heavy metal poisoning are not without risk and may offer only limited benefit in reducing fetal exposure when used during pregnancy.  There is also a risk that maternal chelation therapy will result in mobilisation of the heavy metal from the mother into fetal tissue.  It is therefore recommended that guidelines for non-pregnant adults should be followed in the pregnant patient, with chelation therapy reserved for patients with severe toxicity.

Alternative chelating agents to DMSA may be recommended as first-line treatment of heavy metal poisoning.  Where DMSA is required in the management of severe poisoning then treatment should not be withheld at any stage of pregnancy.  Discussion with UKTIS is recommended in all cases where chelation therapy is being considered.

Exposure to DMSA at any stage in pregnancy would not usually be regarded as medical grounds for termination of pregnancy. However other risk factors may be present in individual cases which may independently increase the risk of adverse pregnancy outcome. Clinicians are reminded of the importance of consideration of such factors when performing case specific risk assessments. Enhanced antenatal surveillance may be warranted and should be decided on a case-by case basis.

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.