First-lineClomid
Clomifene Citrate
Selective oestrogen receptor modulator (SERM)
Oral ovulation induction — first-line for anovulatory PCOS (alongside letrozole).
Oral
First-line for
- Anovulatory PCOS
- Unexplained subfertility (limited evidence)
Mechanism
Blocks oestrogen receptors at hypothalamus → ↑ GnRH → ↑ FSH/LH → follicle recruitment.
Clomid rules
- 50 mg day 2–6 of cycle
- Max 6 cycles (ovarian Ca signal beyond)
- USS monitoring first cycle
Dosing
- Start
- 50 mg OD day 2–6
- Escalate
- 100 → 150 mg if no ovulation
- Max
- 6 cycles lifetime
Contraindications
- AbsolutePregnancy (Category X)
- AbsoluteLiver disease, ovarian cyst, undiagnosed bleeding
Side effects
- Hot flushes
- Visual disturbance (stop if occurs)
- Mood changes
- OHSS (mild)
Fetal & maternal notes
- • Multiple pregnancy rate ~10% (mostly twins).
- • Stop if pregnancy confirmed.
Key interactions
Tamoxifen
CautionAdditive — avoid
Clinical pearls
- 💡 NICE: letrozole now preferred first-line in PCOS (higher live birth rate).
- 💡 Monitor first cycle with USS to avoid OHSS.
Content last reviewed: REPLACE_ME (e.g. 2026-07)
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