Hot flushes can be an uncomfortable side effect of some cancer treatments in both men and women. Here we look at what causes hot flushes and sweats and what you can do about it.

What are hot flushes and sweats?

Hot flushes can vary quite a bit. Some people feel warmth, usually starting in their face and neck. Others feel overwhelmingly hot all over. You may become a bit sweaty or have heavy drenching sweats. These are often described as night sweats because you can get them at night, but really they can happen any time. 

Some people have palpitations (feeling your heart thumping in your chest). You may also feel irritable or panicked.

These feelings usually only last a few minutes. You may have many each day or only one or two a month. Often these symptoms are quite frequent to start with and then come on less often over time.

Which treatments can cause hot flushes and sweats in men?

In men, hormone therapy is generally the only type of treatment that causes hot flushes. If you have prostate cancer, your doctor may want you to have a hormone therapy such as Zoladex (goserelin). This blocks testosterone, which helps to stop prostate cancer growing. Prostate cancer cells are encouraged to grow by this male sex hormone. Blocking testosterone can cause hot flushes and sweats similar to menopausal symptoms in women. 

Testosterone is made by the testicles. Another treatment that blocks testosterone is removing the testicles. This used to be done to treat prostate cancer but hormone therapy is usually used instead these days. Very rarely, men who have testicular cancer in both testicles need to have both testicles removed and will be at risk of hormonal side effects. But usually only one has to be removed and the remaining testicle makes enough testosterone. If you do have both testicles removed for testicular cancer, your doctor will give you testosterone replacement therapy.

Which treatment can cause hot flushes and sweats in women?

For women, several types of treatment that can cause hot flushes. In pre-menopausal women, hot flushes may be caused by anything that cuts off your oestrogen supply. This includes:

  • Surgery that includes removing both ovaries
  • Radiotherapy to both ovaries
  • Chemotherapy 
  • Hormone therapies that temporarily ‘switch off’ your ovaries, such as Zoladex (goserelin)

Not all chemotherapy will cause hot flushes. Whether chemotherapy puts you into early menopause depends on your age, the chemo drugs you have and the total dose.

If you are past your menopause when you have cancer treatment, you may still have hot flushes. Women who’ve had breast cancer often take hormone therapies to lower the risk of their breast cancer coming back. You may have tamoxifen or a medicine called an aromatase inhibitor. This blocks the small amount of oestrogen that your body still makes after menopause. 

Why cancer treatment causes hot flushes

You get hot flushes because your body’s supply of oestrogen or testosterone has been cut off. But doctors don’t completely understand how this comes about. We know that cutting off the sex hormones affects the thermoregulatory centre in the brain, which regulates body temperature. This centre keeps your body temperature within a defined range. But this range is narrower in women who have hot flushes. So a smaller rise in temperature will make you feel too hot.

We also know that levels of some neurotransmitters (chemicals that send messages between nerves) can affect the body’s temperature regulation, including serotonin and norepinephrine. This is why some types of antidepressant can be used to try and treat hot flushes and sweats.

Is there treatment that can stop or reduce hot flushes?

Hormone replacement therapy (HRT) is the only way to completely stop hot flushes. But if you’ve had breast or prostate cancer, your treatment is designed to block these hormones, so you can’t take replacement therapy. Women who’ve had treatment for other types of cancer may be able to have HRT.

Men having hot flushes may be given a hormone treatment called medroxyprogesterone (Megace) or a prostate cancer treatment called cyproterone. Both of these can reduce hot flushes.

If you can’t take hormones, there are a few other medications that have been tried. It’s best to talk to your cancer specialist about this because your choice of treatments may be affected by the type of cancer treatment you’re having. Non hormonal treatments that have been tried include:

  • Venlafaxine and citalopram – drugs normally used for depression and anxiety
  • Clonidine – a tablet normally used for high blood pressure, migraine and headache
  • Gabapentin – a drug used to treat epilepsy and nerve pain

We don’t know exactly how these medicines help. They work better for some people than others. They may reduce the severity of hot flushes as well as the number you have, so if you’re finding hot flushes and sweats distressing, they’re worth discussing with your doctor. Do remember though, that all medicines can have side effects.

How can you manage hot flushes and sweats?

Some people try complementary therapies for hot flushes and sweats, including:

  • Acupuncture
  • Herbal remedies that contain plant oestrogens, such as black cohosh, red clover and soy
  • Evening primrose

Some people find these helpful, but there’s little scientific evidence that they work. If you have a hormone dependent cancer, you need to talk to your doctor before you start taking plant oestrogens. They may increase the risk of your cancer coming back. 

There’s some research evidence that controlled breathing techniques can help to reduce hot flushes. This is called paced respiration. Macmillan has a good explanation of paced respiration. It takes some practice, but isn’t difficult.

There’s a little research that shows that cognitive behavioural therapy (CBT) can help women who’ve had breast cancer with hot flushes. If you’re interested in this, speak to your doctor or nurse.

To manage flushes and sweats yourself, it may help to keep a diary to try and pinpoint anything that triggers them. Some people find that foods or drinks or simply getting too hot can start off a flush. You may find it helps to:

  • Cut down on alcohol and drinks containing caffeine
  • Avoid hot, spicy food
  • Keep your surroundings cool
  • Stop smoking
  • Lose weight

To try and keep comfortable:

  • Wear layers so you can more easily put on or remove clothes
  • Use layers of bedding instead of a duvet
  • Sleep with your window open or have a fan by the bed
  • Carry a small hand fan with you
  • Buy a ‘cooling’ pillow like The Original Chillow
  • Wear cotton or bamboo clothing
  • Try wearing sports or hiking clothing, designed to ‘wick’ away sweat
  • Have warm showers or baths instead of hot ones
  • Use a cold water spray or cooling spritz on your face and wrists if you have a hot flush