How does letrozole work?
Letrozole blocks the aromatase enzyme, which is responsible for converting androgens into oestrogen. This reduces oestrogen levels, which can help slow the growth of certain breast cancers and induce ovulation in women with fertility problems.
What is letrozole used to treat?
Letrozole is commonly prescribed for:
- Breast cancer (especially hormone receptor-positive breast cancer in postmenopausal women)
- Fertility treatment (to stimulate ovulation in women with polycystic ovary syndrome (PCOS) or unexplained infertility)
- Preventing breast cancer recurrence
Who can take letrozole?
Letrozole is suitable for postmenopausal women with hormone receptor-positive breast cancer and some premenopausal women undergoing fertility treatment.
Who might not be able to take letrozole?
Letrozole may not be suitable if you:
- Are pregnant or trying to conceive (unless prescribed for fertility treatment)
- Have severe liver disease
- Have osteoporosis or brittle bones (as letrozole can reduce bone density)
Can I take letrozole if I’m pregnant or breastfeeding?
Letrozole should not be taken during pregnancy or breastfeeding unless specifically prescribed for fertility treatment. If you are taking letrozole for fertility, you must stop taking it once pregnancy is confirmed.
What if I miss a dose?
If you forget a dose, take it as soon as you remember. If it’s close to your next dose, skip the missed one—do not take two doses at once.
How effective is letrozole?
Letrozole is highly effective at reducing oestrogen levels, helping to slow breast cancer growth and promote ovulation in fertility treatments.
What should I do if I take too much?
Taking too much letrozole may cause dizziness, nausea, and severe fatigue. If you feel unwell, seek medical advice immediately.
What dose of letrozole is usually taken?
- For breast cancer: 2.5mg once daily
- For fertility treatment: 2.5mg to 7.5mg daily for 5 days at the start of the menstrual cycle
Your doctor will determine the correct dose based on your condition.
Powered by pharmacies
With over 1,700 pharmacy partners across the UK, you can get the help you need, wherever you are based.
Our website and mobile app make it easy and convenient to manage your health needs and book services at a pharmacy nearby.
What are the side effects of letrozole?
Common side effects include:
- Hot flushes
- Fatigue or tiredness
- Joint pain or stiffness
- Headaches
- Dizziness
Serious side effects, such as osteoporosis, severe bone pain, or liver problems, require urgent medical attention.
How should I take letrozole?
Letrozole is taken as a tablet, once daily, swallowed whole with water.
When should letrozole be taken?
Letrozole should be taken at the same time each day, with or without food.
What are the brand names for letrozole?
Letrozole is available as a generic medicine, but some branded versions include:
- Femara
Final thoughts
Letrozole is an effective treatment for breast cancer and fertility issues, but it should be taken exactly as prescribed. Regular monitoring may be needed for bone health and hormone levels. If you experience side effects, speak to your doctor or pharmacist.
