What it is
A non-steroidal triazole aromatase inhibitor available as an oral tablet.
How it works
Reversibly binds the heme group of the aromatase (CYP19) enzyme, blocking conversion of androgens to estrogens and substantially lowering circulating estradiol.
Where it's used
Used in postmenopausal women with hormone-receptor-positive breast cancer. Off-label, sometimes used by clinicians for ovulation induction or to manage elevated estradiol in men on testosterone therapy.
FDA-approved use
Adjuvant and first/second-line treatment of hormone receptor-positive breast cancer in postmenopausal women.
Tracking it
Letrozole is oral, which makes consistency the whole game — a simple daily check-off with a reminder beats memory every time. with a half-life of about 2 days (48 h), a dose log also lets a tracker model the relative amount still in your system between doses.
Source
OpenFDA
Last reviewed 2026-06-11