How it works

Letrozole is a non-steroidal aromatase inhibitor in the type II category. It attaches to the aromatase enzyme (CYP19A1) and blocks its active site, which interrupts the normal conversion of androgens into estrogen. As estrogen levels fall, luteinizing hormone may rise and uterine weight can decrease. In postmenopausal women, aromatase accounts for most estrogen production, so reducing this activity helps slow or shrink tumors that rely on estrogen. These later-generation inhibitors don’t meaningfully affect hormones like cortisol, aldosterone, or thyroid hormones.

Uses

Letrozole is used in postmenopausal women with hormone-receptor-positive early breast cancer, including those who have already completed tamoxifen therapy. It’s also used for advanced or metastatic breast cancer when tumors are HR-positive or when the hormone receptor status isn’t known. When paired with ribociclib, it can be prescribed for premenopausal, perimenopausal, and postmenopausal women with HR-positive, HER2-negative advanced or metastatic disease.

Who shouldn’t take it

People with a known allergy to the medication or its ingredients should avoid it. It isn’t meant for premenopausal women, and it shouldn’t be taken during pregnancy or while breastfeeding because of the risk of harm to the fetus or infant.

Important considerations

Letrozole can influence bone density over time, so anyone with osteoporosis or cardiovascular issues should be monitored closely. Periodic checks of bone health and heart status may be part of ongoing care.

Interactions

Because Letrozole is processed by liver enzymes—mainly CYP2A6 and CYP3A4—it may interact with other drugs that use the same pathways. This includes tamoxifen, estrogen-containing products, and certain antifungal or antibacterial medications. A full medication review is advised before starting therapy.

Typical dose

Adults usually take one 2.5 mg tablet by mouth each day. The exact duration depends on the condition being treated and the clinician’s guidance.

Storage

Keep the medication in a dry, dark place at room temperature, and store it where children can’t access it.

Compliance information

The product is manufactured under GMP standards and follows applicable regulatory requirements.

Safety notes

Overdose: Get medical help immediately.
Side effects: Any unexpected or persistent symptoms should be reported to a healthcare professional.