Medical Oncologist
Medicines
Letrozole side effects: the complete list and timeline
Most letrozole side effects come from low oestrogen, similar to a stronger menopause. Hot flushes often start early, joint pain within months, and bone thinning over years. This page lists common and less common side effects, explains their usual timing, and describes practical ways to manage them and when to seek help.
NG
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 side effects can letrozole cause, and when do they appear?
- The side effects women report most often
- When side effects commonly appear
- The vocabulary, in plain language
- Honest realities about letrozole side effects
- Practical ways to ease common side effects
- Symptoms to report promptly
- Less common side effects worth knowing about
- What people assume about letrozole side effects
- Common questions about letrozole side effects
The short answer
What side effects can letrozole cause, and when do they appear?
Letrozole works by lowering oestrogen, and most of its side effects come from that low-oestrogen state, which is similar to a stronger version of menopause. Many women have only mild side effects, while others find some of them hard to live with. The most common are hot flushes and sweating, joint pain and stiffness, tiredness, and gradual bone thinning. Other frequent effects include vaginal dryness and discomfort during sex, headaches, dizziness, hair thinning, changes in mood or sleep, weight gain, and a rise in cholesterol. Less commonly, women notice swelling of the hands or feet, tingling in the fingers from carpal tunnel syndrome, a finger that catches or locks, called trigger finger, or skin rashes. Serious side effects are uncommon but include significant bone fractures, marked changes in liver tests, allergic reactions, and chest pain or heart symptoms, which need prompt attention. The timing tends to follow a pattern. Hot flushes often start within the first few weeks. Joint pain usually appears within the first few months and may ease or persist. Bone thinning happens silently over years, which is why bone density scans are done. Many side effects improve over time or can be managed with exercise, practical steps, medicines or switching to another hormone tablet. Reporting them early, rather than stopping treatment, helps you stay on letrozole for the full planned time.
Most side effects come from low oestrogen
They resemble menopause symptoms, sometimes more strongly.
Timing follows a pattern
Flushes come early, joint pain within months, bone loss over years.
Most can be managed
Tell your team early so they can help before you consider stopping.
This page gives general information only. Report side effects to your oncologist or pharmacist.Most common
The side effects women report most often
Not everyone gets these, and their severity varies widely.
Hot flushes and sweating
Sudden warmth, flushing and night sweats, often in the early weeks, and sometimes easing over months.
Joint pain and stiffness
Aching in the hands, wrists, knees, hips or back, often worse in the morning or after sitting.
Exercise is one of the most helpful steps.Tiredness
Feeling more tired than usual, particularly early in treatment or after chemotherapy.
Bone thinning
Gradual loss of bone strength that causes no symptoms until a fracture.
Monitored with
- Bone density scans
- Vitamin D blood tests
- Fracture risk assessment
Timeline
When side effects commonly appear
Time on treatment
What some women notice
First few weeks
Hot flushes, sweating, headaches, tiredness, mild nausea
First few months
Joint pain and stiffness, vaginal dryness, sleep changes
Within the first year
Hair thinning, weight changes, carpal tunnel symptoms, cholesterol rise on blood tests
Over several years
Bone thinning, sometimes leading to fractures if untreated
After stopping
Most side effects ease over weeks to months; bone density may partly recover
Words you may hear
The vocabulary, in plain language
- Aromatase inhibitor musculoskeletal syndrome
- The joint and muscle aches and stiffness linked to letrozole and similar medicines.
- Osteopenia
- Bone density lower than normal, but not low enough to be called osteoporosis.
- Osteoporosis
- Significantly thinned bones that break more easily.
- Carpal tunnel syndrome
- Pressure on a nerve at the wrist causing tingling, numbness or weakness in the fingers.
- Trigger finger
- A finger that catches, clicks or locks when bending and straightening.
- Vaginal atrophy
- Thinning and dryness of vaginal tissues caused by low oestrogen.
Being straight with you
Honest realities about letrozole side effects
Side effects are a real reason some women struggle with letrozole, and it is fair to be open about that.
Some side effects last
Joint pain and vaginal dryness can persist for the whole course of treatment in some women.
Not every symptom is from letrozole
Ageing, previous chemotherapy, arthritis or thyroid problems can cause similar symptoms, so checks may be needed.
Stopping early is common but costly
Many women stop because of side effects, which reduces protection against recurrence.
Alternatives exist
Switching to anastrozole, exemestane or tamoxifen helps some women continue hormone therapy.
What this page cannot tell you
It cannot say which side effects you will get. Your team can help you monitor and manage them.
Talk to our team
Have a question about your situation?
Call the helpline or leave your details, and someone will help you arrange a consultation at the CION centre nearest you. One helpline serves every CION centre.
Call 1800 202 8726
Helpline open 24/7
Managing side effects
Practical ways to ease common side effects
Simple steps help many women, and your team can add medicines when needed.
For hot flushes
Wear cotton layers, keep a fan nearby, limit spicy food, caffeine and alcohol, and ask about non-hormonal medicines such as venlafaxine or gabapentin.
For joint pain
Regular walking, stretching, strength exercises and yoga help; paracetamol or anti-inflammatory painkillers may be suggested.
For vaginal dryness
Non-hormonal moisturisers and water-based lubricants help; ask before using any vaginal oestrogen.
For tiredness
Gentle daily activity, regular sleep and balanced meals help more than long rest.
For bone health
Weight-bearing exercise, calcium, vitamin D and, when needed, bone-strengthening medicines.
Getting help
Symptoms to report promptly
Most side effects are not urgent, but some need attention without delay.
Seek urgent help for
Chest pain, sudden breathlessness, a painful swollen leg, signs of a severe allergic reaction, or yellowing of the skin or eyes.
Report soon
New or worsening bone pain, a fall with pain afterwards, persistent low mood, or numbness in the fingers.
Mention at your next review
Hot flushes, joint stiffness, vaginal dryness, hair thinning or weight changes that bother you.
Keep a symptom diary
Noting when symptoms occur and what helps makes appointments more productive.
Less common
Less common side effects worth knowing about
These affect fewer women, but knowing about them helps you recognise them and mention them early.
Swelling of the hands, feet or ankles
Mild fluid swelling can occur. Report swelling that is sudden, one-sided or painful.
Rash or itchy skin
Usually mild, but a widespread rash, blistering or swelling of the face needs prompt review.
Changes in liver blood tests
These are usually picked up on routine tests rather than noticed as symptoms.
Vaginal bleeding
Any bleeding after menopause should be reported so it can be checked.
Commonly believed
What people assume about letrozole side effects
Side effects mean letrozole is working better.
There is no reliable link between side effect severity and how well it works for an individual.
You just have to put up with side effects.
Many can be eased, and switching medicines is sometimes possible.
Letrozole causes the same blood clot risk as tamoxifen.
Aromatase inhibitors carry a lower clot risk than tamoxifen.
Bone loss causes pain you will notice.
Bone thinning is usually silent, so scans are needed to detect it.
Questions we are asked
Common questions about letrozole side effects
Do letrozole side effects go away?
Some do. Hot flushes often lessen over months, and many women adapt to tiredness. Joint pain and vaginal dryness can persist for some women throughout treatment. Most side effects ease within weeks to months after stopping letrozole, and bone density may partly recover.
Does letrozole cause weight gain?
Some women gain weight during hormone therapy, though it is not clear how much is due to letrozole itself versus menopause, reduced activity or earlier treatments. Regular exercise and balanced eating help. A dietitian can support you if weight is a concern.
Can letrozole cause hair loss?
Letrozole can cause hair thinning in some women, usually gradual and mild, not the complete hair loss seen with some chemotherapy. Gentle hair care and checking thyroid and iron levels can help. Tell your team if thinning worries you.
Does letrozole affect mood?
Some women notice low mood, irritability, anxiety or poor sleep, which may relate to low oestrogen, hot flushes or the stress of cancer. Talk to your team if mood changes last more than a couple of weeks. Counselling and some medicines can help.
Will letrozole raise my cholesterol?
Letrozole can raise cholesterol in some women. Your team may check cholesterol before and during treatment, especially if you have heart risk factors. Diet, exercise and, when needed, cholesterol-lowering medicines manage this effectively.
Can I switch if side effects are too much?
Yes, often. Some women tolerate anastrozole or exemestane better, and others may switch to tamoxifen. A short supervised break followed by a different medicine is sometimes tried. Discuss options with your oncologist rather than stopping on your own.
Does letrozole cause dizziness?
Some women feel dizzy or light-headed, particularly early in treatment. Take care when standing up quickly and avoid driving if you feel affected. Tell your team if dizziness is severe, persistent or comes with other symptoms.
Are side effects worse than with tamoxifen?
They are different rather than simply worse. Letrozole more often causes joint pain and bone thinning, while tamoxifen more often causes blood clots, womb lining changes and some gynaecological symptoms. Your team weighs these against your health and cancer risk.
Meet the Specialists
17+ senior cancer specialists. One panel for your case.
Trained at AIIMS, Tata Memorial, and leading international centres. Combined 150+ years of experience. Every complex case is reviewed by 3+ of them — together.
Medical Oncologist
Dr. C. Raghavendra Reddy
MBBS(Gold Medal), DNB(General Medicine), DM(Medical Oncology)(Gold Medal)
Medical Oncologist
Dr. Bharati Devi Gorantla
MBBS, MD(General Medicine), DM(Medical Oncology)(Adyar,Chennai), ECMO, MRCP SCE(UK)
Medical Oncologist
Dr. Owais Mohammed
MBBS, MD (General Medicine), DrNB (Medical Oncology), ECMO, MRCP SCE (Medical Oncology) (UK)
Medical Oncologist
Medical Oncologist
Surgical Oncologist
Dr. Muralidhar Muddusetty
MBBS (AIIMS), MS (Surgery) (AIIMS), DNB (Surgical Oncology), MRCS (Edinburgh)
Surgical Oncologist
Surgical Oncologist
Surgical Oncologist
Dr. Vinay Mamidala
MBBS, MS(General Surgery), M.Ch(Surgical Oncology), FMAS, FARIS(Ongoing)
Surgical Oncologist
Radiation Oncologist
Radiation Oncologist
Radiation Oncologist
Hematologist
Surgical Oncologist
Dr. Vajja Sandeep Kumar
MBBS, MS (General Surgery), DrNB (Surgical Oncology), FALS Oncology
Surgical Oncologist
Want a specific doctor for your case? Mention them when booking.
Book Free ConsultationBook an appointment with our specialist
Share your name and number — we'll call you back within 30 minutes to schedule your consultation.
Where to find us
Our centres in and around Hyderabad
Addressed by landmark, because that is how this city navigates. Each centre also names the areas it serves, so you can place it without a map. Consultation and day-care Chemotherapy run at every one of them.
Warangal
Vizag
Talk to our team
Speak to a breast cancer specialist
Call the helpline or leave your details, and someone will help you arrange a consultation at the CION centre nearest you. One helpline serves every CION centre.
Call 1800 202 8726
Helpline open 24/7
Sources
- Cancer Research UK — Letrozole (Femara) side effects
- MedlinePlus — Letrozole
- Macmillan Cancer Support — 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.