Question to the Department of Health and Social Care:

To ask His Majesty's Government how many prescriptions for mirtazapine were issued in each year since 2014; how many Yellow Card reports of sexual dysfunction and persistent sexual dysfunction the MHRA received for mirtazapine in each year since 2014; and what consideration NHS England has given to adding sexual dysfunction as a side effect on the patient information leaflets for mirtazapine.

The following table shows the total number of items issued for mirtazapine, each year since 2014 to 2023:

Source: Data was provided by the NHS Business Services Authority, using the British National Formulary chemical substance mirtazapine

Note: Items have been dispensed, but not necessarily prescribed, in England.

The Medicines and Healthcare products Regulatory Agency (MHRA) is responsible for ensuring medicines, medical devices, and blood components for transfusion meet applicable standards of safety, quality, and efficacy. The MHRA rigorously assesses available data, including from the Yellow Card scheme, and seeks advice from their independent advisory committee, the Commission on Human Medicines, where appropriate to inform regulatory decisions.

The MHRA has received a total of 46 Yellow Card reports of sexual dysfunction related reactions suspected to be associated with mirtazapine, four of which include information that suggest the suspected adverse reactions persisted after mirtazapine was withdrawn. The following table shows the number of Yellow Card reports of suspected mirtazapine related sexual dysfunction, and reports of sexual dysfunction that persisted after the drug was withdrawn, each year from 2014 to 2024:

Source: data provided by the MHRA.

It is important to note that the inclusion of a particular report on the MHRA’s system does not necessarily mean that the adverse reactions reported have been caused by the suspect drug. Additionally, the number of reports received should not be used as a basis for determining the incidence of a reaction, as neither the total number of reactions occurring, nor the number of patients using the drug, is known.

The MHRA continuously monitors the safety of medicines on the United Kingdom’s market, including mirtazapine. Reports of suspected adverse reactions are reviewed weekly by a multidisciplinary team as part of the MHRA’s signal detection process. The term signal is used to define any suspected adverse reaction or potential safety concern that requires further evaluation.

Responsibility for adding a side effect to the product information leaflet sits with the MHRA. The product information for mirtazapine reflects the data currently available, and does not include sexual dysfunction as a possible side effect. However, data from Yellow Card reports and other sources such as published studies and periodic safety assessments are kept under continuous review by the MHRA. The marketing authorisation holder has recently submitted the latest periodic safety update report to the MHRA, and this will be carefully assessed. If there is sufficient evidence and associated data about the potential to experience sexual dysfunction as a side effect, the patient information for mirtazapine can be updated.