Medical Oncologist
Medicines
Anastrozole side effects: the complete list and timeline
Most side effects of anastrozole come from low oestrogen, such as hot flushes, joint pain, tiredness and vaginal dryness, while bone thinning builds silently over years. This page lists common and rare side effects, shows when they typically appear, explains practical ways to ease them and describes warning signs that need prompt attention.
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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 side effects can anastrozole cause, and when do they appear?
- The main groups of side effects
- When side effects typically appear, in general terms
- The vocabulary, in plain language
- The honest picture on side effects
- Practical ways to manage common side effects
- Side effects that need prompt attention
- Options when side effects are hard to live with
- What people assume about anastrozole side effects
- Common questions about anastrozole side effects
The short answer
What side effects can anastrozole cause, and when do they appear?
Most side effects of anastrozole come from the low oestrogen levels it creates, so many feel like strong menopause symptoms. The commonest are hot flushes and night sweats, joint pain and stiffness, tiredness and weakness, headache, feeling sick, a mild rash, vaginal dryness and lower sex drive, hair thinning and changes in mood or sleep. Over time, anastrozole also thins the bones, which raises the risk of fractures, and it can raise cholesterol a little. Less common effects include tingling or numbness in the hands from carpal tunnel syndrome, a finger that catches or locks, and changes in liver blood tests. Rarely, people have serious skin reactions with blistering or peeling, allergic swelling of the face or throat, or inflammation of the liver, which need urgent care. Many side effects appear in a predictable pattern. Hot flushes and tiredness often start in the first weeks. Joint pain and stiffness usually begin within the first few months and may peak within the first year, then ease for some women. Bone thinning builds up silently over years and is found on scans rather than felt. Not everyone gets side effects, and most are mild to moderate. When they are troublesome, simple measures such as exercise, painkillers, vaginal moisturisers or non-hormonal hot flush treatments help, and switching to another aromatase inhibitor or to tamoxifen is an option. Report side effects rather than stopping on your own, because staying on treatment is what protects you.
Most effects mimic menopause
Hot flushes, dryness and joint aches reflect low oestrogen.
Bone thinning is silent
It does not cause symptoms until a fracture, so scans are used to check.
Help is available
Most side effects can be eased, and switching tablets is an option.
This page gives general information only. It is not a complete list. Read the leaflet in your pack and ask your team about anything new.By type
The main groups of side effects
Grouping side effects makes them easier to recognise and discuss.
Menopause-type symptoms
Hot flushes, night sweats, vaginal dryness, lower sex drive, poor sleep and mood changes.
Joints and muscles
Aching or stiff joints, especially in the hands, knees, hips and back, often worst in the morning.
Staying active often helps stiffness.Bones and blood fats
Gradual bone thinning, higher fracture risk, and a modest rise in cholesterol in some women.
General effects
Tiredness, weakness, headache, feeling sick, mild rash and hair thinning.
Less common
- Tingling and numbness in the hands
- A finger that locks or clicks
- Changes in liver blood tests
Timeline
When side effects typically appear, in general terms
Time on treatment
What some women notice
First few weeks
Hot flushes, tiredness, headache, mild nausea
First few months
Joint pain and stiffness, vaginal dryness, sleep changes
Within the first year
Joint symptoms often at their worst, then may ease
Over years
Gradual bone thinning and possible cholesterol rise
After stopping
Most symptoms ease over weeks to months; bones partly recover
Words you will hear
The vocabulary, in plain language
- Aromatase inhibitor musculoskeletal syndrome
- The joint and muscle pain and stiffness linked with anastrozole and similar tablets.
- Carpal tunnel syndrome
- Pressure on a nerve in the wrist causing tingling, numbness or weakness in the hand.
- Trigger finger
- A finger that catches, clicks or locks when bent.
- Vasomotor symptoms
- Hot flushes and night sweats.
- Osteoporosis
- Thin, fragile bones that break more easily.
- Stevens-Johnson syndrome
- A rare, serious skin reaction with blistering that needs emergency care.
Being straight with you
The honest picture on side effects
Side effect lists can look frightening. It helps to keep them in perspective.
Lists include rare effects
Leaflets must mention effects that very few people get. Most women experience only a few of the listed effects, and many are mild.
Joint pain is a real problem for many
It is one of the main reasons women stop early. Taking it seriously and treating it helps many women stay on treatment.
Not every symptom is the tablet
Age, earlier chemotherapy and natural menopause cause similar symptoms, so causes can overlap.
What this page cannot tell you
It cannot say what you will experience. Your team can assess any symptom you notice.
Talk to our team
Have a question about your situation?
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Easing side effects
Practical ways to manage common side effects
Most side effects respond to simple steps, and your team can add treatments if needed.
Joint pain and stiffness
Regular walking, stretching, yoga, strength exercises and keeping a healthy weight help many women. Paracetamol or anti-inflammatory painkillers, used as advised, can ease pain.
Hot flushes
Cotton clothing, a fan, cool drinks and limiting alcohol and spicy food help. Non-hormonal medicines such as venlafaxine or gabapentin may be prescribed.
Vaginal dryness
Regular non-hormonal moisturisers and lubricants during sex ease discomfort.
Tiredness and mood
Exercise, a regular sleep routine and talking to someone help. Tell your team about lasting low mood.
Warning signs
Side effects that need prompt attention
Serious side effects are uncommon, but you should know what to look out for.
Seek emergency help
For swelling of the face, lips, tongue or throat, difficulty breathing, or a widespread rash with blisters or peeling skin.
Contact your team the same day
For yellowing of the skin or eyes, dark urine, severe tummy pain, or chest pain.
Contact your team soon
For new or worsening bone pain, a fracture after a minor fall, vaginal bleeding, or numbness in the hands that affects daily tasks.
When it is too much
Options when side effects are hard to live with
Stopping on your own is the option most likely to cause harm. There are usually better choices.
A short supervised break
Some oncologists suggest a brief pause to see whether symptoms settle, then restarting or switching.
Another aromatase inhibitor
Letrozole or exemestane suit some women better, though side effects may return.
Tamoxifen
For women who cannot tolerate any aromatase inhibitor, tamoxifen is a well-established alternative.
Commonly believed
What people assume about anastrozole side effects
Everyone gets every side effect on the leaflet.
Most women have only a few, and many are mild.
Joint pain means the cancer has spread to bones.
Joint aches are a common tablet effect, though new, lasting bone pain should be checked.
Resting is the best treatment for stiffness.
Regular movement and exercise usually help more than rest.
Side effects last for the whole course unchanged.
Many settle after the first year, and most ease after stopping.
Questions we are asked
Common questions about anastrozole side effects
How common is joint pain on anastrozole?
Joint pain and stiffness are among the most common side effects of all aromatase inhibitors, reported by a large share of women. For most it is mild to moderate. Exercise, weight management and pain relief help, and switching tablets is possible if needed.
Will anastrozole make me gain weight?
Weight gain is not a clearly established direct effect. Many women gain weight around menopause and after treatment for other reasons, such as lower activity. Regular exercise and balanced meals help keep weight steady.
Can anastrozole affect my memory?
Some women describe poor concentration or forgetfulness. Studies are mixed, and tiredness, poor sleep, low mood and earlier chemotherapy all play a part. Tell your team if it affects daily life, as sleep and mood can often be improved.
Is the tingling in my hands from anastrozole?
It may be carpal tunnel syndrome, which is more common on aromatase inhibitors. Wrist splints at night and hand exercises can help. Tell your team, as other causes such as nerve damage from chemotherapy or diabetes may need checking.
Does anastrozole cause vaginal bleeding?
Light bleeding occasionally happens in the first weeks, especially after switching from tamoxifen. Any bleeding after menopause should be reported so your doctor can check for other causes and decide whether tests are needed.
Do side effects mean the tablet is working?
No reliable link has been shown. Women with few side effects benefit too. Side effects are not a test of whether anastrozole is working, and troublesome ones should be reported and treated rather than endured.
Will side effects go away when I stop?
Most, such as hot flushes and joint stiffness, ease over the weeks to months after stopping. Bone density often recovers partly. If a side effect continues after stopping, tell your doctor so other causes can be checked.
Should I stop anastrozole if I get a rash?
A mild rash is fairly common; contact your team for advice. Stop and seek emergency help if a rash spreads quickly, blisters, peels or comes with swelling of the face or difficulty breathing.
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Sources
- NHS — Side effects of anastrozole
- Macmillan Cancer Support — Anastrozole
- MedlinePlus — Anastrozole
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.