Key points
- Chemotherapy can make periods irregular or stop them. The chance rises with age: about 3 in 4 women over 40 and about 1 in 4 women under 35 [2].
- Periods stopping does not always mean permanent menopause: in many younger women, periods come back in the months that follow [1, 3]; this is why you need to avoid pregnancy during treatment [1, 4].
- Hot flushes are the most common symptom, especially with tamoxifen and with the aromatase inhibitor tablets such as letrozole and anastrozole [4, 6].
- Non-hormonal treatments work: talking therapy, venlafaxine, gabapentin, oxybutynin and newer medicines [5, 7, 8].
- Vaginal dryness improves with lubricants and vaginal moisturisers [9].
- Look after your bones: early menopause and some hormone tablets weaken the bones; exercise, a good diet and sometimes medicines help [1, 6, 10].
- Do not stop your hormone tablets on your own because of side effects. Most side effects can be treated; talk to your doctor [5, 12].
Why does cancer treatment cause menopause?
The ovaries make the female hormone oestrogen and release an egg each month. Some cancer treatments reduce or stop the work of the ovaries and bring on the symptoms of menopause earlier than expected [1]:
- chemotherapy, especially a group of medicines called "alkylating agents" [1]
- radiotherapy to the pelvis near the ovaries [1]
- surgery to remove both ovaries [1]
- hormone therapy, that is, medicines that block or lower female hormones [1]
The symptoms of this early menopause are like those of a natural menopause, and sometimes stronger [1]: irregular or no periods, hot flushes and night sweats, vaginal dryness, mood swings, and joint and muscle aches. In the long term, weaker bones and a higher risk of heart disease are also possible [1].
Does chemotherapy cause menopause? Periods during chemotherapy
During chemotherapy, many women's periods become irregular or stop [1]. Whether this change is temporary or permanent depends mostly on your age and the type of medicines [1, 3]. In a review of more than 70 studies of women with breast cancer, periods stopped after chemotherapy in about half of the women [2]:
- under 35: about 1 in 4
- 35 to 40: about 4 in 10
- over 40: about 3 in 4
Taking tamoxifen also made it more likely that periods would stop [2]. The older you are, the more common and the longer-lasting the loss of periods [2, 3].
Periods after chemotherapy: how long until they come back?
The answer is different for every woman. In a study that recorded the periods of women aged 20 to 45 with breast cancer day by day, one month after the standard course of chemotherapy (the medicines doxorubicin and cyclophosphamide, with or without paclitaxel or docetaxel) only about 1 in 6 women had a monthly period. Periods came back gradually over about 9 months, and after that almost half of these women had monthly periods [3]. Age, the type of medicines and taking tamoxifen all affected whether periods came back [3].
Sometimes the ovaries still release eggs and periods come now and then; sometimes the damage is permanent and early menopause follows [1]. Not having periods does not necessarily mean you cannot get pregnant; avoid pregnancy during treatment and talk to your doctor about the right method [1, 4]. If you would like to have children in the future, read: Fertility and sex during cancer treatment.
Tamoxifen and periods stopping; hormone tablets in younger women
Tamoxifen can make periods irregular or stop them [4]. In the study above, women who took tamoxifen after chemotherapy had fewer periods in the second year [3]. Because tamoxifen harms an unborn baby, women who have not yet gone through menopause must avoid pregnancy with a non-hormonal method (such as condoms) while taking it and for about 2 months after stopping it [4].
Anastrozole on its own does not work in women who have not gone through menopause [6]; this is why, before starting these tablets in younger women, the doctor checks whether you are past menopause. Read about these medicines: tamoxifen, letrozole, anastrozole and exemestane.
Hot flushes with tamoxifen and other hormone tablets: what can I do?
A hot flush is a sudden feeling of heat in the face, neck and chest, often with sweating; when it happens at night it is called a "night sweat" [5]. Hot flushes are the most common side effect of tamoxifen: in a large study, about 2 in 3 women who took tamoxifen had hot flushes, although about half of the women who took a dummy tablet had them too [4]. With anastrozole, about 1 in 3 women had hot flushes, slightly fewer than with tamoxifen [6].
The options below are listed in order, from simple measures to medicines. Choose with your doctor which suits you best.
Ways to reduce hot flushes
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Talking therapy and hypnotherapy
"Cognitive behavioural therapy" is a type of talking therapy that teaches you ways to cope with hot flushes and the worries that come with them; in women with breast cancer it made hot flushes less bothersome. Hypnotherapy (with a trained therapist) also reduced how often hot flushes happened and how bad they were [5].
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- 3
Layered clothing and a cool room
Layered clothing made of breathable fabric, a fan and a cooler bedroom are simple measures that may help, but there is not yet strong evidence that they reduce hot flushes [5].
- 4
Venlafaxine and similar medicines
Venlafaxine and several similar medicines from the antidepressant group, at low doses, reduce hot flushes; taking them for hot flushes does not mean you are depressed [5]. Nausea or dizziness is common in the first week or two and usually gets better [5]. If you take tamoxifen, the antidepressants paroxetine and fluoxetine are not suitable because they may reduce the effect of tamoxifen; venlafaxine is a safer choice [5].
- 5
Gabapentin
Gabapentin, a medicine for epilepsy and nerve pain, roughly halved how bad hot flushes were at an adequate dose in a study of 420 women with breast cancer, much more than a dummy tablet [7]. Drowsiness and dizziness are common in the first week, so taking it at night suits women whose sleep is disturbed by hot flushes [5].
- 6
Oxybutynin
Oxybutynin, a medicine for bladder leakage, reduces hot flushes. A dry mouth and difficulty passing urine are among its side effects, and long-term use in older people may be linked with weaker memory [5].
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Newer medicines
Fezolinetant and elinzanetant are new medicines that act on the brain's temperature control centre [5]. Elinzanetant was tested in a large study of women taking hormone tablets to treat or prevent breast cancer and, on average, cut moderate to severe hot flushes from about 11 a day to fewer than 4, more than a dummy tablet did; its most common side effects were headache, tiredness and sleepiness [8].
Vaginal dryness and pain during sex
Vaginal dryness is a symptom of early menopause [1] and can make sex painful. The first step is a lubricant during sex together with a vaginal moisturiser used regularly [9]. If this is not enough, your doctor may in some cases consider a low-dose vaginal oestrogen cream or other medicines; if you have had breast cancer, always make this decision with your cancer doctor [9]. Talking to a counsellor or a sexual health specialist also helps [9]. Read more: Fertility and sex during cancer treatment.
Joint pain, weight and bones: side effects of letrozole, anastrozole and tamoxifen
- Joint and muscle pain: a common side effect of aromatase inhibitors; with anastrozole about 1 in 3 women had joint problems, more than with tamoxifen [6]. In one study, regular exercise (about two and a half hours of aerobic exercise such as brisk walking a week, plus strength training twice a week) reduced the worst joint pain by nearly a third after one year [12].
- Weight: in large studies of women past menopause, tamoxifen and anastrozole did not raise weight more than a dummy tablet; weight gain was seen mainly in the first year of treatment and only in some women [11]. Exercise and healthy eating help; read: Nutrition during cancer treatment.
- Bones: aromatase inhibitors lower bone density, and fractures were slightly more common with them than with tamoxifen [6]. Tamoxifen did not cause bone loss in women past menopause, but in women before menopause it was linked with lower bone density [4]. Early menopause also raises the risk of osteoporosis [1]. Your doctor may ask for a bone density scan; a good diet, exercise and, if needed, bone-strengthening medicines (such as bisphosphonates or denosumab) help [10].
- Blood fats: anastrozole may raise cholesterol; your doctor may ask for a blood cholesterol test [6].
Can I take menopausal hormone therapy?
Menopausal hormone therapy is the most effective treatment for hot flushes [5]. But for cancers that grow with hormones, such as most breast cancers, it is usually not suitable [5]. If your cancer was not hormone-dependent (lymphoma, for example) and you have gone through an early menopause, hormone therapy may be offered; make the decision with your doctor [5]. Read more: Does menopausal hormone therapy (HRT) increase the risk of breast cancer?
When should I call my doctor?
In these situations, contact your doctor within the next few days:
- unusual vaginal bleeding, a change in vaginal discharge, or pain or pressure in the pelvis, if you take tamoxifen or have taken it in the past [4]
- a new breast lump or changes in your vision [4]
- a late period or a possible pregnancy during treatment [1, 4]
- a broken bone, even after a simple fall [10]
- hot flushes, poor sleep or joint pain that are disrupting your life or making you think about stopping your hormone tablets; these side effects can be treated [5, 12]
- a sudden worsening of mood or thoughts of harming yourself after starting a medicine for hot flushes; report this the same day [5]
A swollen, painful leg, sudden or unexplained shortness of breath, chest pain, or sudden weakness on one side of the body and difficulty speaking can be signs of a blood clot or a stroke; call your local emergency number straight away [4]. If you are still having chemotherapy and have a fever, read: Fever and warning signs during chemotherapy.
Frequently asked questions
Can menopause after chemotherapy go away? Will my periods come back?
Sometimes, yes. In many younger women periods come back in the months after treatment; in one study, most of this recovery happened in about the first 9 months after chemotherapy [3]. The older you are, the more likely your periods are to stop [2]. Talk to your doctor about how your ovaries are working.
My periods stopped during chemotherapy; can I still get pregnant?
Are hot flushes with tamoxifen normal?
Does tamoxifen cause weight gain?
What are the side effects of letrozole and anastrozole in women?
The most common side effects are hot flushes, joint and muscle pain, lower bone density and sometimes raised cholesterol [6]. Regular exercise reduces joint pain [12], and a bone density scan shows whether you need treatment to prevent fractures [10]. Read the details on the letrozole and anastrozole pages.
Related pages
Amenorrhoea, vasomotor symptoms and bone health (for doctors)
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Chemotherapy-induced amenorrhoea (CIA). Meta-analysis of 75 breast cancer studies (using 19 different definitions of CIA): pooled rate 55% (95% CI 50–60); 26% under 35, 39% at 35–40 and 77% over 40 years; age over 40 and tamoxifen were risk factors supported by strong evidence [2]. In a prospective cohort of 595 women aged 20–45 (stage I–III): in the month after AC (with or without a taxane) about 16%, and after CMF 48%, had monthly bleeding; after AC there was gradual recovery over about 9 months followed by a plateau with bleeding in almost half, and after CMF a continual decline to about 18%; tamoxifen reduced bleeding by 15% in months 12–24 [3]. Amenorrhoea does not mean ovulation has definitely stopped; with tamoxifen, non-hormonal contraception is needed until about 2 months after stopping [1, 4].
Non-hormonal treatment of vasomotor symptoms (NAMS 2023). Level I: CBT, clinical hypnosis, SSRIs/SNRIs, gabapentin and fezolinetant; oxybutynin Levels I–II; weight loss Levels II–III; clonidine and pregabalin are not recommended. Doses: venlafaxine 37.5–150 mg/day (start 37.5), desvenlafaxine 100–150, citalopram and escitalopram 10–20 mg/day; gabapentin 900–2,400 mg/day in divided doses (start 100–300 mg at night); oxybutynin 2.5 or 5 mg twice daily up to 15 mg extended release; fezolinetant 45 mg/day. With tamoxifen, paroxetine and fluoxetine inhibit CYP2D6 (reduced conversion to endoxifen); venlafaxine, desvenlafaxine, escitalopram or citalopram are safer. Long-term anticholinergic use may be associated with cognitive decline in older people. HT is the most effective treatment but is not a suitable option in oestrogen-dependent cancers [5]. Gabapentin 900 mg/day (420 women with breast cancer) reduced the hot flush severity score at week 8 by 46% vs 15% with placebo; 300 mg/day was not effective [7]. Elinzanetant 120 mg daily (OASIS-4; 474 women aged 18–70 on endocrine therapy for HR-positive breast cancer or its prevention; baseline about 11.4 moderate to severe episodes a day): change at week 4 −6.5 vs −3.0 and at week 12 −7.8 vs −4.2 (P < .001); the most common adverse events were headache, fatigue and somnolence [8].
Genitourinary symptoms. First, lubricants plus vaginal moisturisers; low-dose vaginal oestrogen, lidocaine and DHEA in some cases; psychosexual counselling for all [9].
Aromatase inhibitors and bone. ATAC (anastrozole label; anastrozole vs tamoxifen): hot flushes 36% vs 41%, joint symptoms 36% vs 29%, all fractures 10% vs 7%, weight gain 9% in both, raised cholesterol 9% vs 3.5%; lumbar spine and total hip BMD fell with anastrozole; consider monitoring BMD and cholesterol [6]. Tamoxifen was associated with significant lumbar spine and hip bone loss in premenopausal women, with no evidence of bone loss in postmenopausal women [4]. ASCO: assess fracture risk with validated tools, DXA when risk is substantial, optimise nutrition and exercise, and when indicated a bisphosphonate or denosumab at osteoporosis doses [10]. Exercise (150 minutes of aerobic exercise a week plus supervised strength training twice a week for 12 months; 121 women with AI-induced arthralgia) reduced worst joint pain by 1.6 points (29%) vs a 0.2-point increase with usual care (P < .001) [12]. In IBIS-I, ATAC and IBIS-II, 12-month weight change did not differ significantly between tamoxifen, anastrozole and placebo [11].
Related cancer types
Related guides
References
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Numbers in the text, such as [1], refer to these sources. Sources with a “Study card” button are summarised in the site’s evidence library.
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This page is based on reputable scientific sources and was last updated on 28 October 2026. The content of this website is for educational and informational purposes only and does not replace consultation, diagnosis or treatment by a specialist physician. Consult your treating physician about any treatment decision.
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