You're braced for sickness and tiredness during chemo treatment, and then you find yourself throwing the duvet off at three in the morning, soaked through, for the fourth night running.
Hot flushes and night sweats affect a very large proportion of people treated for breast cancer, and they're often more severe and longer-lasting than the flushes of a natural menopause. They're also common with other treatments that affect hormones. If yours feel disproportionate, you're not imagining it.
Why night sweats happen during chemo
Several parts of treatment can trigger night sweats. Chemotherapy can affect how the ovaries work, sometimes pushing you into an early or temporary menopause. Hormone therapies like tamoxifen and aromatase inhibitors change how oestrogen behaves in the body. Ovarian suppression or removal does it too. Men on hormone therapy for prostate cancer get flushes for similar reasons.
The common thread is a fairly sudden drop in hormone levels, which upsets the part of the brain that regulates your temperature. It gets the signal wrong and dumps heat.
Some people find things settle after a few months. Others find they carry on for as long as the hormone treatment does, which can be years. Neither means anything has gone wrong.
Say something rather than putting up with it
This is the important bit. A lot of people assume flushes are simply the price of treatment and never mention them.
There are non-hormonal prescription options that help many people, and your team can talk you through what's suitable alongside your particular treatment. There's also good evidence that a specific kind of cognitive behavioural therapy helps with flushes, and some areas run menopause-specific CBT courses.
Standard HRT is usually not an option after a hormone-sensitive cancer, but that doesn't mean there's nothing available, so its best to ask.
If flushes are making you consider stopping your hormone treatment, tell someone straight away rather than stopping. That's exactly the situation your team wants to know about.
Be careful with anything herbal
This is worth spelling out, because real harm can happen.
St John's Wort interferes with how the body processes several cancer drugs, including tamoxifen and docetaxel, and it's not recommended for people with a history of breast cancer.
Black cohosh, sage, red clover, soy isoflavones and various menopause supplements come up constantly online. Some are plant oestrogens, and their safety after a hormone-sensitive cancer isn't established.
Check with your oncology team or pharmacist before taking anything, including things sold as natural. Tell them everything you're taking, including anything you buy over the counter.
Working out what triggers your night sweats
Most people have a trigger, and they're not the same for everyone. Common ones include:
- Hot drinks, particularly coffee
- Alcohol
- Spicy food
- Warm rooms and hot baths
- Stress and rushing
- Smoking
Keeping a rough note for a fortnight often reveals a pattern. You don't have to give everything up, knowing that your evening glass of wine costs you a bad night is useful information either way.
How to cope with night sweats during chemo
Layers are the best strategy - Something you can take off in ten seconds and put back on when you go cold afterwards, which you will.
- Cotton, linen and bamboo next to the skin rather than synthetics
- A cardigan or overshirt rather than a jumper you'd have to wrestle off
- A small handheld or desk fan
- Cold water to hand, and a cold drink at the first sign of a flush
- A cool flannel or a facial spray in your bag
- Loose necklines, since anything tight round the throat makes it worse
Slow breathing helps some people ride one out, and it's free to try. Breathe out for longer than you breathe in, and keep going for a couple of minutes.
Getting through the night
Night sweats are the worse half of this, because broken sleep makes everything else harder to cope with.
- Keep the bedroom cooler than feels normal, and leave a window open
- Layer the bed with several thin covers rather than one thick duvet, so you can shed them
- Cotton or bamboo bedding, never polyester
- Keep a spare nightshirt and a towel by the bed, so a change at 3am takes thirty seconds
- A fan on a timer, or a cooling pillow
- Cold water within reach
Chemo Headwear matters more here than people expect. A lot of the heat you're dumping goes through your head, and if you're wearing something warm and synthetic to bed you'll cook in it.
Bamboo is the fabric to look for. It breathes considerably better than cotton and doesn't hold heat or dampness against the skin, which is exactly the problem with a woolly hat at 2am. Our bamboo hats and sleep caps are made for this, and it's the single most common reason customers tell us they came back for a second one.
If you're also fighting the cold, and many people swing between the two, our guide to keeping your head warm at night covers the other side of it.
When to mention it to your team
Beyond the flushes themselves, tell someone if:
- You have a temperature alongside the sweats, which needs ruling out urgently through your chemo helpline
- Sweats come with unexplained weight loss
- Sleep is so broken it's affecting how you're coping
- You're thinking about stopping your hormone treatment
- Your mood is dropping, which broken sleep does to people
Night sweats with a fever are a different situation to menopausal sweats, and that one is a phone call rather than a wait-and-see.
It does get more manageable
Not always quickly, and not for everyone at the same pace. Many people find the worst of it settles over the first year, and most find they get better at handling it even when the flushes carry on.
Layers, a cool room, breathable fabrics and a conversation with your team will get you most of the way. And it's worth having that conversation, because putting up with something for three years that could have been treated is a miserable way to spend three years.
Frequently asked questions
Why does cancer treatment cause hot flushes? Chemotherapy, hormone therapies like tamoxifen and aromatase inhibitors, and ovarian suppression all cause hormone levels to drop, often quite suddenly. That disrupts the part of the brain that regulates temperature.
How long do hot flushes last after chemotherapy? It varies. Some people find they settle within months. Others get them for as long as their hormone treatment continues, which can be several years. Many find they become more manageable over time.
Can I take HRT for hot flushes after breast cancer? Usually not, as HRT is generally avoided after a hormone-sensitive cancer. There are non-hormonal prescription options and menopause-specific CBT, so it's worth asking your team what's suitable for you.
Are herbal remedies safe for hot flushes during cancer treatment? Check first. St John's Wort interferes with tamoxifen and docetaxel and isn't recommended after breast cancer. Black cohosh, sage and soy supplements have uncertain safety after hormone-sensitive cancers.
What should I wear in bed for night sweats? Breathable natural fabrics. Bamboo handles heat and moisture better than cotton and much better than synthetics. Layer thin covers instead of one thick duvet, and keep a spare nightshirt by the bed.
When should I worry about night sweats? Sweats with a temperature need a call to your chemo helpline rather than a wait. Also mention unexplained weight loss, or sweats severe enough to affect how you're coping.
Not medical advice. Always check with your oncology team or pharmacist before taking anything new, including supplements and herbal remedies.
