Clomiphene is a drug that is often used to induce ovulation and treat infertility. It works by blocking estrogen receptors at the hypothalamus. This blocking of estrogen signaling at the hypothalamus increases GnRH and eventually LH production, which in turn works to stimulate ovulation. Stimulation of ovulation treats infertility, and is particularly useful in patients with PCOS. 

Key Points

  • Clomiphene
    • Mechanism
      • Antagonizes estrogen receptors at the hypothalamus
        • Increased LH/FSH stimulates ovulation
        • Clomiphene is technically a selective estrogen receptor modulator (SERM), although antagonist effects are more important than agonist effects.
        • Antagonism of estrogen receptors prevents negative feedback inhibition of hypothalamic-pituitary-axis, increasing LH and FSH production → stimulates ovulation
    • Indications
      • Infertility
        • E.g. from Polycystic Ovarian Syndrome (PCOS)
          • Increased LH and FSH induce ovulation and increase chance of pregnancy
    • Adverse Effects
      • Hot flashes
        • Disruption of normal HPA activity
      • Enlarged ovaries
      • Multiple simultaneous pregnancies
      • Visual disturbances