Letrozole use: what to know

Letrozole lowers oestrogen production by blocking aromatase, an enzyme involved in making oestrogen after menopause. Lower oestrogen can slow or control cancers that use hormone signals to grow. It is prescribed for particular diagnoses and treatment goals, so a tablet labelled letrozole should not be started, shared or stopped without clinical advice. Read about [Aromatase Inhibitor Drugs](/materials/aromatase-inhibitor-drugs/).

Common concerns include hot flushes, sweating, joint or muscle aches, tiredness, mood changes and vaginal dryness. Longer treatment can affect bone strength and cholesterol, so your team may review symptoms, medicines and bone health.

Take letrozole exactly as prescribed, at a consistent time if that helps you remember. If you miss a dose, follow the instructions from your clinic or pharmacist rather than doubling the next dose. Keep a list of medicines and supplements, and report new pain, stiffness, vaginal symptoms or mood changes. Your team may arrange examinations and blood tests and may discuss bone-strengthening measures. See [Aromatase Inhibitor Therapy](/treatments/systemic-therapy/aromatase-inhibitor-therapy/) for treatment context.

Seek urgent help for chest pain, sudden breathlessness, one-sided weakness, facial swelling or trouble breathing. Contact your oncology team promptly for severe or persistent bone pain, a new fracture, marked depression, heavy bleeding or symptoms suggesting an allergic reaction. Do not stop letrozole because of a troublesome effect without discussing a safe plan.

Why is letrozole recommended for me? How long should I take it? What should I do after a missed tablet? Should my bone health be checked? Which medicines or supplements should I avoid? When will my response and side effects be reviewed?