First-lineFemara
Letrozole (ovulation induction)
Aromatase inhibitor — off-label ovulation induction
First-line ovulation induction in PCOS — better live-birth vs clomifene.
Oral
First-line for
- Anovulatory PCOS infertility (NICE 2023)
Mechanism
Inhibits ovarian aromatase → ↓ oestradiol → ↑ hypothalamic GnRH/FSH → follicular growth. Shorter half-life than clomifene — less antioestrogenic on endometrium.
"Letrozole > clomifene in PCOS"
- Days 2–6
- Start 2.5 mg
- Higher live-birth rate
Dosing
- Start
- 2.5 mg OD days 2–6
- Titrate
- Up to 7.5 mg; max 6 cycles
Contraindications
- AbsolutePregnancy, breastfeeding, hepatic dysfunction
Side effects
- Hot flushes
- Fatigue
- Headache
- Multiple pregnancy (lower than clomifene)
Fetal & maternal notes
- • Stop as soon as pregnancy confirmed — teratogenic in animal studies
Key interactions
Tamoxifen
CautionReduces letrozole efficacy
Clinical pearls
- 💡 Preferred in PCOS with obesity
- 💡 Endometrial thickness usually superior to clomifene
Content last reviewed: REPLACE_ME (e.g. 2026-07)
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