MHRA reminder on the use of carbimazole in females of child-bearing age

20 Feb 2019

The MHRA has issued a reminder to all healthcare professionals to ensure females of child-bearing age use effective contraception during  carbimazole treatment.

The Medicines and Healthcare products Regulatory Agency (MHRA) has issued a reminder to all healthcare professionals, including community pharmacy teams, of the patient safety advice related to the supply of carbimazole to female patients of child-bearing age.


Risk with carbimazole

Use of carbimazole in pregnancy, especially during the first trimester, and at doses greater than 15mg per day, is associated with an increased risk of congenital malformations.


Advice for healthcare professionals

  • Women of child-bearing age on carbimazole should use effective contraception during treatment
  • Carbimazole should only be prescribed in pregnancy after a strict individual risk/benefit assessment of the patient
    • The lowest effective dose should be prescribed which does not require additional thyroid hormone administration
    • Close monitoring of the mother, foetus and neonate is recommended during pregnancy
  • Women who become pregnant, suspect pregnancy or plan to have a baby during treatment with carbimazole should be seen by their prescriber without delay


Reporting drug reactions

The MHRA are reminding healthcare professionals to report all suspected adverse drug interactions (ADRs) to the Yellow Card Scheme – this is via the Yellow Card website or Yellow Card App available on iOS devices and Android devices


NPA advice for pharmacists

  • Ensure females of child-bearing age are aware of the risks of carbimazole and are taking effective contraception
  • Check whether females who are pregnant and on carbimazole treatment are being monitored
  • Make necessary notes on the patient’s medication record
  • Report suspected ADRs to the Yellow Card Scheme


For further information on this or any other query, please contact the NPA Pharmacy Services team on 01727 891 800 or email

 Produced by the NPA Pharmacy Services team February 2019.