Published: 25 August 2022
Revised:  27 March 2023

Safety Information

Monitoring communication

Medsafe emphasises that patients should NOT stop using any medicine or medical device subject to a monitoring communication. If you have any concerns with a medicine or medical device you are using, please contact your healthcare professional. A monitoring communication does not mean that the medicine or medical device causes an adverse event.

Abnormal uterine bleeding and oral anticoagulants (blood thinners)

Update to original communication 

During the monitoring period (25 August 2022 to 28 February 2023), the Centre for Adverse Reactions Monitoring (CARM) received 4 reports relating to abnormal uterine bleeding with rivaroxaban. No reports were received for apixaban, dabigatran or warfarin.  

Currently the data sheets for oral anticoagulants list bleeding and/or urogenital haemorrhage in section 4.8. Similar information is also included in the corresponding consumer medicine information (CMI) leaflets.  

To increase awareness about this side effect, Medsafe will include an article about oral anticoagulants and abnormal uterine bleeding in a future edition of Prescriber Update.  

The benefit risk balance for oral anticoagulants (apixaban, rivaroxaban, dabigatran, and warfarin) remains positive.

Original communication  

Monitoring closes 28 February 2023

Medsafe is reviewing the risk of abnormal uterine bleeding (changes to normal menstrual periods) in individuals using oral anticoagulant medicines. These medicines are sometimes called ‘blood thinners’.

The aim of this communication is to obtain more information about this topic, by encouraging prescribers or patients to report any adverse events of abnormal uterine bleeding with oral anticoagulant use.

Products affected
Additional information
Regulator actions

Products affected

Product name (active ingredient) Sponsor
Coumadin (warfarin) Viatris Limited
Eliquis (apixaban) Pfizer New Zealand Limited
Marevan (warfarin) GlaxoSmithKline NZ Limited
Pradaxa (dabigatran) Boehringer Ingelheim (NZ) Ltd
Xarelto (rivaroxaban) Bayer New Zealand Limited

The products in the table belong to a group of medicines called anticoagulants.

Anticoagulants are prescribed to treat and/or prevent blood clots by interrupting the clot-forming process.1

Additional information

Abnormal uterine bleeding (AUB) describes any changes to normal menstrual periods. This includes menstrual bleeding that is heavy (menorrhagia), excessively frequent or infrequent, irregular, or occurs between cycles (intermenstrual bleeding).2

AUB events have been reported in women receiving oral anticoagulants.3 Pre-menopausal women are more at risk of AUB.3

See the consumer medicine information (CMI) and data sheets of each medicine for advice on how to take oral anticoagulant medicines and the known side effects.

Search for consumer medicine information and data sheets

Regulator actions

Medsafe is placing these medicines on the Medicines Monitoring ( )scheme to understand more about AUB-related events that may occur with apixaban, dabigatran, rivaroxaban, and warfarin.


Consumers and healthcare professionals are encouraged to report suspected adverse reactions to medicines to the Centre for Adverse Reactions Monitoring (CARM).

Medsafe cannot give advice about an individual’s medical condition. If you have concerns about a medicine you are taking, please talk to your health professional.


  1. Health Navigator New Zealand. 2022. Anticoagulants 10 Aug 2022. URL: (accessed 11 August 2022).
  2. Bannow BS. 2020. Management of heavy menstrual bleeding on anticoagulation. Hematology Am Soc Hematol Educ Program 2020(1): 533-7. DOI: 10.1182/hematology.2020000138 (accessed 27 June 2022).
  3. Godin R, Marcoux V and Tagalakis V. 2017. Abnormal uterine bleeding in women receiving direct oral anticoagulants for the treatment of venous thromboembolism. Vascul Pharmacol 93-95: 1-5. DOI: 10.1016/j.vph.2017.05.001 (accessed 27 June 2022).
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