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GnRH antagonist Pregnancy: CONTRAINDICATED in pregnancy and breast-feeding (§4.3). §4.6, verbatim: 'There are no or limited amount of data from the use of linzagolix in pregnant women. Studies in animals have shown that exposure to linzagolix early in pregnancy may increase the risk of early pregnancy loss… Yselty is contraindicated during pregnancy. Treatment should be discontinued if pregnancy is confirmed.' Breast-feeding: 'Available pharmacodynamic/toxicological data in animals have shown excretion of linzagolix in milk… A risk to newborns/infants cannot be excluded. Yselty is contraindicated during breast-feeding.' Women of childbearing potential: linzagolix 'has not been demonstrated to provide contraception… Women of childbearing potential at risk of pregnancy have to use effective non-hormonal contraception while on treatment with Yselty.'

Linzagolix

Brand names: Yselty

An orally active gonadotrophin-releasing hormone (GnRH) receptor antagonist used in the management of symptoms associated with uterine fibroids.

Adult dose

Dose: UTERINE FIBROIDS — §4.2 verbatim: '100 mg or, if needed, 200 mg once daily with concomitant hormonal add-back therapy (ABT, estradiol 1 mg and norethisterone acetate 0.5 mg tablet once daily)'; '100 mg once daily for women in whom ABT is not recommended or who prefer to avoid hormonal therapy'; '200 mg once daily for short-term use (< 6 months) in clinical situations when reduction of uterine and fibroid volume is desired'. §4.2 adds: 'Fibroid size may increase when the treatment is stopped. Due to the risk of bone mineral density (BMD) decrease with prolonged use, the 200 mg dose without concomitant ABT should not be prescribed for longer than 6 months.' ENDOMETRIOSIS — §4.2 verbatim: '200mg once daily with concomitant hormonal add-back therapy'. Before starting: 'Pregnancy must be ruled out prior to initiating treatment with Yselty. Yselty should preferably be started in the first week of the menstrual cycle and should be taken continuously once daily.'
Route: Oral. §4.2 verbatim: 'Oral use. Yselty can be taken with or without food… The 200 mg dose is to be taken as two times a 100 mg tablet.' §4.2 also states: 'Yselty treatment should be initiated and supervised by a physician experienced in the diagnosis and treatment of uterine fibroids and/or endometriosis.'
Frequency: Once daily, continuously — §4.2: 'Yselty can be taken without interruption.' MISSED DOSE, verbatim: 'If a dose is missed, treatment must be taken as soon as possible and then continued the next day at the usual time.'
Max: 200 mg once daily — the highest dose stated in §4.2 for either licensed indication, and it is taken as two 100 mg tablets. A duration ceiling is attached to it: the 200 mg dose WITHOUT concomitant add-back therapy 'should not be prescribed for longer than 6 months' because of the risk of bone mineral density decrease; the labelled short-term 200 mg fibroid regimen is likewise '< 6 months'. No dose above 200 mg once daily appears anywhere in the fetched SPC.
THE ADD-BACK FIGURES ARE NOT LINZAGOLIX'S DOSE: estradiol 1 mg with norethisterone acetate 0.5 mg once daily is the co-prescribed hormonal add-back tablet named in §4.2, not a dose of linzagolix. SPECIAL POPULATIONS, §4.2 verbatim: hepatic — 'No dose adjustment is necessary in women with mild or moderate hepatic impairment (Child-Pugh A or B). Yselty should be avoided in women with severe hepatic impairment (Child-Pugh C)'; renal — 'Prescribers are recommended to monitor for adverse reactions in women who have mild renal impairment (eGFR = 60‑89 mL/min) although no dose adjustment is required. Yselty should be avoided in women with moderate (eGFR = 30‑59 mL/min), severe renal impairment (eGFR < 30 mL/min) or end-stage renal disease.' §4.6: linzagolix 'has not been demonstrated to provide contraception' — women of childbearing potential at risk of pregnancy must use effective NON-hormonal contraception, and any hormonal contraception must be stopped before initiation (§4.4).

Paediatric dose

NO PAEDIATRIC DOSE EXISTS IN THE FETCHED LABEL. §4.2 'Paediatric population', verbatim: 'There is no relevant use of Yselty in children aged under 18 years for the indication of treatment of moderate to severe symptoms of uterine fibroids. The safety and efficacy of Yselty in children aged under 18 years for the indication of treatment of endometriosis has not been established.' dosePerKg is deliberately null — the adult regimen is a fixed tablet dose, never a per-kilogram figure. Verify any use below 18 years against a current children's formulary and specialist advice.

Dose independently re-sourced from UK Summary of Product Characteristics (SPC) via the eMC — clinician-reviewed. Always confirm against the product SmPC and your local formulary before prescribing.

Contraindications

  • §4.3, verbatim: 'Hypersensitivity to the active substance(s) or to any of the excipients listed in section 6.1'.
  • §4.3, verbatim: 'Pregnancy or breast-feeding (see section 4.6)'.
  • §4.3, verbatim: 'Known osteoporosis'.
  • §4.3, verbatim: 'Genital bleeding of unknown aetiology'.
  • §4.3, verbatim: 'Contraindications related to ABT should be respected if concomitant ABT is given'.
  • Not contraindications but use bars in §4.2/§4.4: avoid in severe hepatic impairment (Child-Pugh C) and in moderate or severe renal impairment (eGFR < 60 mL/min) or end-stage renal disease.

Side effects

  • §4.8 summary, uterine fibroids, verbatim: 'The most common adverse reactions reported in the pivotal phase 3 clinical studies in the uterine fibroid-treated population were hot flushes and headaches, which were reported with higher frequency at higher doses and less frequently when ABT was taken concomitantly. Hot flushes were reported in 5.2%, 9.6%, 10.1% and 31% of women treated with 100 mg with ABT, 200 mg with ABT, 100 mg and 200 mg, respectively. Similarly, headaches were reported more frequently at higher doses and decreased with ABT (1.4%, 2.4%, 4% and 6.2% for 100 mg with ABT, 200 mg with ABT, 100 mg and 200 mg, respectively).'
  • §4.8 summary, endometriosis, verbatim: 'The most common adverse reactions reported in the endometriosis population treated with the recommended dose of 200 mg with ABT included hot flushes (6.3%) and headache (5.7%).'
  • Very common (≥1/10) with linzagolix 200 mg and with 100 mg without ABT: hot flush.
  • Common (≥1/100 to <1/10) across the dose groups in §4.8 Table 1: mood disorders, decreased libido (uncommon in some dose groups), headache, hot flush, nausea/vomiting, upper abdominal pain, constipation, elevated liver enzymes, hyperhidrosis, night sweats.
  • Uncommon (≥1/1,000 to <1/100): hypertension, decreased libido, upper abdominal pain, constipation (per dose group in Table 1).
  • Bone: §4.4, verbatim — 'In some women treated with Yselty, who had normal bone mineral density (BMD) at start of treatment, BMD loss varying from > 3-8% was reported.'
  • INCOMPLETE LIST — §4.8 was cut at the source-fetch limit inside the adverse-reaction table, so reactions listed after the skin and subcutaneous tissue disorders row were never retrieved.

Monitoring

  • §4.2 and §4.4, bone mineral density: 'In patients with risk factors for osteoporosis or bone loss, a dual X-ray absorptiometry (DXA) scan is recommended prior to starting Yselty treatment… A DXA scan is recommended after 1 year of treatment for all women, and there is a need for continued BMD monitoring thereafter.' §4.4 adds that thereafter BMD assessment is recommended annually for Yselty 100 mg, or at a frequency set by the treating physician for 100 mg with ABT and 200 mg with ABT, and that 'If the risks of BMD decrease exceed the potential benefit of treatment with Yselty, treatment should be discontinued.'
  • §4.4, before starting or restarting: 'a complete medical history (including family history) must be taken. Blood pressure must be measured, and a physical examination must be performed… During treatment, periodic check-ups must be carried out according to standard clinical practice.'
  • §4.2/§4.4: 'Pregnancy must be ruled out prior to administering or re-initiation of Yselty', and any hormonal contraception must be stopped before initiation.
  • §4.2, mild renal impairment (eGFR 60–89 mL/min): 'Prescribers are recommended to monitor for adverse reactions… although no dose adjustment is required.'
  • §4.4, QT: 'Linzagolix marginally increases the QT interval but showed no evidence of clinically relevant risk of QT prolongation or Torsade de Pointes. Caution should be exercised in patients who have known cardiovascular disease, family history of QT prolongation or hypokalaemia, and in concomitant use with medicinal products known to prolong the QT interval.' (§4.4 was cut at the source-fetch limit immediately after this paragraph — later monitoring guidance was never retrieved.)

Clinical monograph

How it works

It competitively blocks pituitary GnRH receptors, dose-dependently suppressing luteinising hormone and follicle-stimulating hormone release and thereby lowering circulating oestradiol.

Prescribing in practice

  • Because oestrogen suppression reduces bone mineral density, assess bone health and use combined hormonal add-back therapy where indicated, limiting treatment duration accordingly.
  • Exclude pregnancy before starting and ensure effective non-hormonal or appropriate contraception during treatment.
  • Review the SPC for cautions in hepatic impairment and for interactions before prescribing.

Monitoring

Monitor menstrual bleeding response, bone mineral density over prolonged use, and liver-related parameters in line with current prescribing references.

Counselling the patient

  • Menopause-like effects such as hot flushes may occur, particularly without add-back hormone therapy.
  • Do not become pregnant while taking this medicine and use reliable contraception.
  • Attend bone-density and review appointments as arranged.

Evidence & guidelines

Linzagolix was evaluated for heavy menstrual bleeding due to uterine fibroids in the PRIMROSE phase 3 trials.

Reference: NICE TA945; SmPC; Drug verified in RxNorm (NLM); confirm dosing against the manufacturer SPC (eMC). Verify against your local formulary and current prescribing references before prescribing. The structured dose values shown have been reviewed by a clinician. Monograph status: clinician-reviewed (2026-07-04).

Related

Curated clinical cross-links plus same-class fallbacks.

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