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More than 794 000 prescriptions are written for therapeutic (as opposed to contraceptive) use of norethisterone (or its synonym norethindrone) in the UK each year (data on file, Bayer plc). Although its licensed indications include “metropathia haemorrhagica, premenstrual syndrome, postponement of menstruation, endometriosis, menorrhagia and dysmenorrhea”1 most clinicians prescribe it to stop an episode of heavy menstrual bleeding or use it ‘off-label’ to help regulate irregular bleeding associated with hormonal contraception such as progestogen-only implants or injectables.2 In these situations, the dose prescribed is generally 10–20 mg per day, compared to the 0.5–1 mg per day in contraceptive formulations. Some have called therapeutic norethisterone a ‘lifestyle’ drug as its seasonal prescribing peaks during the UK summer months suggest an increased use solely for delaying menstruation during holidays.3
High-dose (therapeutic) norethisterone was thought to be free of serious adverse effects. Doubts, however, first started to emerge in 1999 when two studies4 ,5 reported an increased incidence of venous thromboembolism (VTE) in women taking high-dose oral progestogens for therapeutic indications. No particular progestogen was named but the authors cautioned …
Competing interests Dr Mansour declares no support from any organisation for the submitted work. Dr Mansour has received research grants and honoraria for attending advisory board meetings, developing and delivering educational presentations from Astellas, Bayer plc, Consilient Healthcare, HRA Pharma and MSD. Dr Mansour declares that there are no other relationships or activities that could appear to have influenced the submitted work.
Provenance and peer review Not commissioned; externally peer reviewed.
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