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Aromatase Inhibitor — Ovulation Induction

Letrozole (Ovulation Induction)

Brand names: Femara

Letrozole used off-label for ovulation induction, particularly in women with polycystic ovary syndrome, where it is taken for a short course in the early part of the menstrual cycle to stimulate ovulation.

Dosing — not shown for this use

The product information we hold does not support a dose for this page's specific use, route or population, so none is shown. Follow your local or national guideline, and confirm against the product SmPC.

The licensed dosing — for the medicine's licensed uses, which may differ from this page's — is on Letrozole.

Clinical monograph

How it works

Letrozole is an aromatase inhibitor that blocks conversion of androgens to oestrogens, reducing oestrogen negative feedback so that pituitary FSH secretion rises and drives follicular development.

Prescribing in practice

  • It is used in the days before conception and must be confined to the recommended early-cycle course while pregnancy is excluded, as letrozole is not for use once pregnancy is established.
  • There is a possibility of multiple pregnancy, though generally lower than with some other ovulation-induction agents, and cycles should be monitored.
  • Common effects include hot flushes, fatigue and headache during the treatment course.

Monitoring

Monitor the ovulatory response, for example with ultrasound tracking or mid-luteal progesterone, to confirm ovulation and guide subsequent cycles.

Counselling the patient

  • Take the tablets only on the specific cycle days advised, then stop.
  • Confirm timing of intercourse or further tests with your fertility team.
  • Hot flushes and tiredness during the course are common and temporary.

Evidence & guidelines

Randomised trial evidence and NICE-endorsed practice support letrozole as an effective ovulation-induction agent in polycystic ovary syndrome, with comparable or better live-birth outcomes than clomifene in this group.

Reference: NICE NG68 (Fertility); Legro et al. NEJM 2014; ESHRE/ASRM PCOS Guidelines 2023; Drug verified in RxNorm (NLM); confirm dosing against the manufacturer SPC (eMC). Verify against your local formulary and current prescribing references before prescribing. Monograph status: clinician-reviewed (2026-07-04).

Related

Curated clinical cross-links plus same-class fallbacks.

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