11/07/2025
Why do we use Letrozole?
Letrozole is a medication used for ovulation infuction.
Letrozole is an aromatase inhibitor which works by lowering estrogen levels temporarily, telling your brain to release more FSH (follicle-stimulating hormone). This increase in FSH will hopefully be enough to stimulate a follicle to grow and an egg to mature.
We commonly use letrozole for patients with PCOS, since irregular or absent ovulation is a major reason they struggle to get pregnant and a large study confirmed it was the drug of choice for PCOS patients (who tend to have a higher baseline estrogen level due to their high follicle count). It can also be used in other cases of anovulation or in unexplained infertility.
It’s taken for 5 days, starting anywhere between cycle day 3-7. We monitor with an ultrasound to see the response, but some clinics recommend OPK testing or mid-luteal progesterones.
The highest risk with letrozole is the risk of twin pregnancy, but ultimately it cna be a safe and effective option for ovulation.