Medical Oncologist
Medicines
Letrozole (Femara) for breast cancer: the complete patient guide
Letrozole is an aromatase inhibitor tablet that lowers oestrogen after menopause, used for hormone receptor positive breast cancer. It is taken daily, often for five years after early cancer, or with targeted tablets in advanced cancer. This page explains, in general terms, how it is used, side effects and safety.
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Medically reviewed by Dr. Naresh GunduConsultant Medical Oncologist · MBBS, DNB (Internal Medicine), DM (Medical Oncology, AIIMS) · last reviewed September 2026, next review due September 2027
On this page
- What is letrozole and how is it used for breast cancer?
- The main situations letrozole is prescribed for
- Letrozole in brief
- The vocabulary, in plain language
- Honest realities about letrozole
- Side effects and how they are managed
- Important safety points
- What people assume about letrozole
- Common questions about letrozole
The short answer
What is letrozole and how is it used for breast cancer?
Letrozole, also known by the brand name Femara and sold in India under many generic names, is a hormone therapy tablet for breast cancer that is hormone receptor positive, meaning its growth is fuelled by oestrogen. It belongs to a group of medicines called aromatase inhibitors. After menopause, the ovaries stop making most oestrogen, but the body still produces small amounts in fat, muscle and other tissues using an enzyme called aromatase. Letrozole blocks this enzyme, lowering oestrogen levels so hormone-sensitive cancer cells are starved of the signal that helps them grow. It is mainly used for women who have gone through menopause. In early breast cancer, it is usually taken after surgery, and sometimes radiotherapy and chemotherapy, to lower the chance of the cancer coming back. It may be started straight away, or after a few years of tamoxifen, and treatment commonly lasts five years, sometimes longer. In advanced breast cancer, letrozole is often combined with a targeted tablet such as ribociclib, palbociclib or abemaciclib. Premenopausal women can take it only if their ovaries are switched off with ovarian suppression. It is taken once a day, with or without food. Common side effects include hot flushes, joint pain and stiffness, tiredness and gradual bone thinning, so bone health is monitored during treatment. Taking it every day for the full planned time gives the greatest benefit.
It lowers oestrogen after menopause
Letrozole blocks the aromatase enzyme that makes oestrogen outside the ovaries.
It is for hormone-sensitive cancer
It only helps cancers that are oestrogen receptor positive.
Staying on it matters
Taking it daily for the planned years gives the most protection.
This page gives general information only. Whether letrozole suits you is a decision for your oncologist.When it is used
The main situations letrozole is prescribed for
Letrozole has several roles, depending on the stage of cancer and menopausal status.
After surgery for early cancer
Taken for several years to lower the chance of hormone-sensitive breast cancer returning in postmenopausal women.
After tamoxifen
Some women switch to letrozole after a few years of tamoxifen, or take it as extended treatment afterwards.
The sequence depends on your cancer and side effects.Before surgery
Occasionally used to shrink a hormone-sensitive tumour before surgery, especially in older women.
Advanced breast cancer
Used to control cancer that has spread, often with a targeted tablet.
Common partners
- Ribociclib
- Palbociclib
- Abemaciclib
At a glance
Letrozole in brief
Question
General answer
How is it taken?
One tablet once a day, at the dose your doctor prescribes, with or without food
Who is it for?
Mainly postmenopausal women with hormone receptor positive breast cancer
How long is it taken?
Often five years after early cancer, sometimes longer; ongoing in advanced cancer
Most common side effects
Hot flushes, joint pain and stiffness, tiredness and bone thinning
Key monitoring
Bone density scans, cholesterol checks and regular reviews
Words you may hear
The vocabulary, in plain language
- Aromatase inhibitor
- A medicine that blocks the enzyme making oestrogen outside the ovaries, such as letrozole, anastrozole or exemestane.
- Hormone receptor positive
- Breast cancer cells that have receptors for oestrogen or progesterone and can be fuelled by these hormones.
- Adjuvant hormone therapy
- Hormone treatment taken after surgery to lower the chance of cancer returning.
- Ovarian suppression
- Treatment that switches off the ovaries so a premenopausal woman can take an aromatase inhibitor.
- Bone density scan
- A low-dose X-ray scan, often called a DEXA scan, that checks for bone thinning.
- Generic medicine
- A version made by another company, containing the same active drug as the original brand.
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Being straight with you
Honest realities about letrozole
Letrozole is an effective, widely used medicine, but it helps to be realistic about what it can and cannot do.
It lowers risk, it does not remove it
Letrozole reduces the chance of cancer returning, but some women still have a recurrence despite taking it.
Side effects can be hard to live with
Joint pain and hot flushes lead some women to stop early, which reduces the benefit.
It does not work on hormone-negative cancer
If your cancer has no hormone receptors, letrozole will not help it.
Premenopausal women need extra treatment
Without ovarian suppression, letrozole can stimulate the ovaries rather than lower oestrogen.
What this page cannot tell you
It cannot say whether letrozole, anastrozole, exemestane or tamoxifen is best for you. Your oncologist can.
Side effects
Side effects and how they are managed
Many women have mild or manageable side effects, and most can be eased with practical steps or medicines.
Hot flushes and sweating
Layered clothing, a fan, avoiding triggers such as spicy food and alcohol, and some non-hormonal medicines can help.
Joint pain and stiffness
Regular exercise, gentle stretching, walking and simple painkillers help many women; switching to another aromatase inhibitor is sometimes tried.
Bone thinning
Weight-bearing exercise, calcium and vitamin D, and bone-strengthening medicines when needed protect bones.
Vaginal dryness
Non-hormonal moisturisers and lubricants often help; discuss any hormone creams with your oncologist first.
Tiredness and mood
Activity, good sleep and talking about low mood with your team can make a difference.
Safety
Important safety points
These points help you take letrozole safely over the years of treatment.
Not in pregnancy
Letrozole can harm an unborn baby. If there is any chance you could become pregnant, use reliable non-hormonal contraception.
Avoid oestrogen products
Hormone replacement therapy and many herbal products with plant oestrogens may work against letrozole.
Tell every doctor
Let dentists, pharmacists and other doctors know you take letrozole, including before any new medicine.
Check with your team about supplements
Some supplements and traditional remedies may interact or affect the liver.
Keep regular reviews
Appointments allow side effects, bone health and cholesterol to be checked.
Commonly believed
What people assume about letrozole
Letrozole is a form of chemotherapy.
It is a hormone therapy tablet that lowers oestrogen, not chemotherapy.
If I feel well, I can stop after a year or two.
The benefit comes from taking it for the full planned time.
Generic letrozole does not work as well as the brand.
Approved generics contain the same active drug; buy from licensed pharmacies.
Joint pain means the cancer has spread to bones.
Joint pain is a common side effect, though new or severe bone pain should be checked.
Questions we are asked
Common questions about letrozole
How long will I take letrozole?
After early breast cancer, letrozole is commonly taken for five years, either on its own or after a few years of tamoxifen. Some women at higher risk are advised to continue for longer. In advanced cancer, it is usually taken for as long as it keeps the cancer controlled. Your oncologist will set the plan.
Can premenopausal women take letrozole?
Only with ovarian suppression. In women whose ovaries still work, letrozole alone can trigger the ovaries to make more oestrogen. With injections or surgery that switch off the ovaries, letrozole can be used and may suit some higher-risk younger women.
What are the most common side effects?
Hot flushes, joint pain and stiffness, tiredness, sweating and gradual bone thinning are the most commonly reported. Some women also notice vaginal dryness, hair thinning, headaches or raised cholesterol. Many side effects ease over time or can be managed, so tell your team rather than stopping.
Is letrozole better than tamoxifen?
For postmenopausal women, studies show aromatase inhibitors such as letrozole lower the chance of recurrence somewhat more than tamoxifen alone. However, they have different side effects, and tamoxifen may suit some women better. Your oncologist will weigh your risk, bones and other health conditions.
Will letrozole thin my bones?
Lowering oestrogen can gradually reduce bone density. A bone density scan is usually done at the start and repeated during treatment. Exercise, calcium, vitamin D and, when needed, bone-strengthening medicines help protect your bones.
Can I drink alcohol while taking letrozole?
There is no known direct interaction, but alcohol can worsen hot flushes, affect bone health and is linked with a higher breast cancer risk. Most guidance suggests keeping alcohol low or avoiding it. Ask your team for advice suited to you.
What if I forget a tablet?
Take it as soon as you remember, unless it is nearly time for the next one, in which case skip the missed tablet. Do not take two tablets together. Occasional missed doses are not dangerous, but a daily reminder helps keep treatment regular.
Is generic letrozole safe?
Approved generic letrozole contains the same active drug and is widely used in India. Buy from licensed pharmacies, check packaging and expiry dates, and try to stay with one manufacturer where possible. Ask your pharmacist or oncologist if you have concerns about a product.
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Sources
- National Cancer Institute — Letrozole
- Cancer Research UK — Letrozole (Femara)
- MedlinePlus — Letrozole
This page is general information, not a prescription. Do not change or stop any treatment based on what you read here. If anything is worrying you, contact your own treating team — or call our helpline and we will help you reach the right specialist.