Sounds like 'let-ro-zole'

Letrozole is used to treat some types of breast cancer. Letrozole is commonly called Letrole.

What is letrozole?

Letrozole is used to treat breast cancer in women who have gone through menopause. This type of breast cancer is called oestrogen receptor-positive breast cancer (cancer that grows in response to the hormone oestrogen). Letrozole belongs to a group of medicines called aromatase inhibitors.

After menopause, the ovaries no longer produce oestrogen but it continues to be made at low levels in fat and other tissues. This happens when an enzyme called aromatase changes other hormones into oestrogen through a complex process. Aromatase inhibitors are a type of medicine that block this process and reduce the amount of oestrogen in the body. In this way exemestane slows or stops the growth of the cancer cells. Read more about aromatase inhibitors.


In Aotearoa New Zealand letrozole is available as tablets

  • The usual dose of letrozole is 1 tablet once a day.
  • Letrozole is a long-term treatment; you may have to take it for several years.
  • Always take letrozole exactly as your doctor has told you. The pharmacy label on your medicine will tell you how much to take, how often to take it, and any special instructions.

How to take letrozole?

  • Take letrozole at the same time each day, either in the morning or the evening. 
  • You can take letrozole with or without food.
  • If you forget to take your dose, take it as soon as you remember, but if it is nearly time for your next dose, just take the next dose at the right time. Do not take double the dose.
  • Do not stop taking letrazole suddenly; speak to your doctor before stopping.

Things to consider while you are taking letrozole

  • Letrozole can make you drowsy, especially when you first start taking it. Avoid driving and doing other tasks where you need to be alert until you know how this medicine affects you. It's best to take it at bedtime.
  • Letrozole can interact with some other medicines and herbal supplements, so check with your doctor or pharmacist before starting letrozole and before starting any new products.
  • If you haven't gone through the menopause yet, let your doctor know. Another option might be better for you.
  • If you have osteoporosis, let your doctor know.

What are the side effects of letrozole?

Like all medicines, letrozole can cause side effects, although not everyone gets them. Often side effects improve as your body gets used to the new medicine.

Hot flushes and sweats

This is quite common when you are taking letrozole and is often mild, but this can vary. Hot flushes and sweats may improve after the first few months. You can try to reduce this effect by not smoking, reducing alcohol and avoiding hot drinks containing caffeine, such as tea and coffee. Try to dress in layers, so you can remove clothes as needed, and wear clothes made from natural fabrics, such as cotton. If hot flushes are troubling you, tell your doctor or nurse. There are some medicines that can help to reduce flushes.

Other side effects

Side effects What should I do?
  • Nausea, feeling sick or vomiting
  • Constipation or diarrhoea (runny poos)
  • Try taking letrozole with food or just before bed
  • Tell your doctor if troublesome
  • Changes in appetite
  • Thinning hair
  • Joint pain, stiffness 
  • Feeling tired, or dizzy or have lack of energy 
  • Headache
  • Low mood
  • These may improve with time 
  • Tell your doctor if troublesome
  • Avoid driving if you feel tired or dizzy
  • Vaginal bleeding 
  • Swollen legs or feet
  • Tingling in the arms or hands
  • Tell your doctor immediately or ring HealthLine 0800 611 116
Did you know that you can report a side effect to a medicine to CARM (Centre for Adverse Reactions Monitoring)? Report a side effect to a product

Learn more


  1. Letrozole New Zealand Formulary
Credits: Sandra Ponen, Pharmacist. Reviewed By: Angela Lambie, Pharmacist, Auckland Last reviewed: 12 Feb 2019