Taking letrozole: what to know

Letrozole is an aromatase inhibitor. It reduces the body's production of oestrogen, a hormone that can encourage some breast cancer cells to grow. Your oncology team chooses it when this hormone pathway is relevant to your diagnosis or ongoing risk of recurrence. It may be prescribed after other treatment or as part of longer-term endocrine therapy.

Common effects include hot flushes, sweating, tiredness, low mood, sleep changes, vaginal dryness and aching or stiffness in muscles and joints. Lower oestrogen can also affect bone strength over time. These effects do not mean the medicine is harming the cancer treatment, but persistent symptoms deserve a review.

Take letrozole exactly as prescribed, usually at the same time each day, with or without food. Swallow the tablet as directed. If you miss a dose, follow the instructions from your pharmacist or oncology team rather than doubling the next dose. Keep an up-to-date list of medicines, supplements and herbal products because some can affect treatment.

Tell your team about new joint pain, troublesome hot flushes, mood changes or vaginal symptoms. They can check whether another cause is present and suggest suitable support. Ask whether you need bone-health assessment, weight-bearing activity advice or monitoring tailored to your health.

Contact your cancer team promptly for severe or worsening pain, a new fracture, marked weakness, persistent low mood, or symptoms that make daily activities difficult. Seek urgent medical help for sudden chest pain, difficulty breathing, one-sided weakness, facial swelling, or a severe allergic reaction.

Ask why letrozole is recommended for you, how long you are expected to take it, and what to do after a missed tablet. Ask how your bone health will be monitored, which pain-relief options are suitable, and whether any of your medicines or supplements should be changed.