Letrozole

Sounds like 'let-ro-zole'

Easy-to-read medicine information about letrozole – what it is, how to take letrozole safely and possible side effects.

Type of medicine Also called
  • Used for breast cancer in women
  • Belongs to a group of medicines known as aromatase inhibitors
  • Letara®
  • 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 is a type of medicine called an aromatase inhibitor. Aromatase is an enzyme that helps the body make oestrogen. Letrozole blocks (inhibits) the activity of aromatase. This reduces the amount of oestrogen in your body, and in this way, slows the cancer's growth.

In New Zealand, letrozole is available as tablets. 

Dose

  • The usual dose of letrozole is 1 tablet (2.5 mg) once a day.
  • Letrozole is a long-term treatment; you may have to take it for several years.
  • Always take your 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.
  • It is not harmful if you miss a dose of letrozole. 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.

Precautions – before starting letrozole

  • Are you still having menstrual periods? If you have not gone through the menopause you should not take letrozole.
  • Do you have osteoporosis (a condition that causes your bones to be thinner and weaker than normal)?
  • Do you have problems with your liver?
  • Are you taking any other medicines, including medicines you can buy without a prescription, such as herbal and complementary medicines?

If any of these apply, it’s important that you tell your doctor or pharmacist before you start letrozole. Sometimes a medicine isn’t suitable for a person with certain conditions, or it can only be used with extra care.

Possible side effects

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
  • Try taking letrozole with food or just before bed
  • Tell your doctor if troublesome
  • Increased appetite
  • Falling hair
  • Joint pain, stiffness 
  • Feeling tired, lack of energy 
  • These may improve with time 
  • Tell your doctor if troublesome
  • Vaginal bleeding 
  • Swollen legs or feet
  • Tell your doctor immediately or ring HealthLine 0800 611 116

Interactions

Letrozole may interact with some medicines and herbal supplements so check with your doctor or pharmacist before starting letrozole or before starting any new medicines or supplements.

Learn more

References

  1. Letrozole New Zealand Formulary
Credits: Sandra Ponen, Pharmacist. Last reviewed: 07 Jan 2019