Letrozole-Induced Menstrual Cycles

Understanding Letrozole's Effects on Menstrual Cycles

Letrozole is an aromatase inhibitor that can act as an ovarian stimulant while suppressing estrogen levels, making it effective for inducing ovulation in women who have experienced amenorrhea 1
When used for ovulation induction, letrozole enhances ovarian stimulation while keeping estrogen levels near physiologic levels 1
Aromatase inhibitors are primarily used as adjuvant treatment for hormone-positive breast cancers but have been repurposed for ovulation induction in infertility patients 1

The optimal duration of aromatase inhibitor treatment is not well established, as noted in clinical guidelines 2, 3
It's important to note that aromatase inhibitors do not adequately suppress ovarian estrogen synthesis in women with functioning ovaries, which explains why they can be effective in restoring menstrual cycles 4, 5

For women using letrozole after a period of amenorrhea, monitoring of cycle length and pattern is recommended, but cycles of 38-40 days do not require intervention 6
Signs that would warrant concern include bleeding that saturates a large pad or tampon hourly for at least 4 hours, signs of hemodynamic instability, or an abrupt change from the current bleeding pattern to heavy bleeding 6