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(Date of issue: May 2017, Version: 2)

This is a UKTIS monograph for use by health care professionals. For case-specific advice please contact UKTIS on 0344 892 0909. To report an exposure please download and complete a pregnancy reporting form. Please encourage all women to complete an online reporting form.


Pyridostigmine is a reversible cholinesterase inhibitor used in the treatment of myasthenia gravis (MG), paralytic ileus, and post-operative urinary retention. Pyridostigmine is also included in Nerve Agent Pre-treatment Sets (NAPS) issued to military personnel.

Available data on pyridostigmine exposure in human pregnancy are limited to case reports describing the treatment of MG. Transient neonatal myasthenia gravis (TNMG) and arthrogryposis multiplex congenita (AMC) are recognised neonatal complications of maternal myasthenia gravis and are attributed to the transplacental transfer of maternal antibodies to acetylcholine (Ach) receptors. The published data thus focus primarily on the link between maternal MG and these two fetal conditions, and not on the teratogenic potential of pyridostigmine. The very limited published data do not, however, suggest pyridostigmine is a major teratogen, although in one case report the authors postulate a potential effect of high dose pyridostigmine (>40mg/kg/day) on fetal brain development. Data relating to other adverse pregnancy outcomes are too limited to facilitate an evidence-based assessment of risk and pregnant women being prescribed pyridostigmine should be made aware of this lack of data.

Inadvertent exposure to pyridostigmine at any stage of pregnancy would not usually be regarded as medical grounds for termination of pregnancy. Enhanced antenatal surveillance may be warranted and should be decided on a case-by-case basis. Other risk factors may also 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. Discussion with UKTIS is recommended in all cases of exposure to pyridostigmine at any stage of pregnancy. 

Where treatment with pyridostigmine is clinically indicated it should not be withheld because of pregnancy but should be decided using a materno-fetal risk-benefit analysis.
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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 or to ensure you are using the most up-to-date version.