Like Great Britain is entering the fifth heat wave of the summermany of us will be used to waking up in streams of sweat by now.
But a top doctor has warned this symptom should never be ignored – as it could be an early sign of it cancer.
“During warm weather, almost everyone will experience warmer and more uncomfortable nights,” says Dr. Jiri Kubes, radiation oncologist at the Proton Therapy Center at University College Hospital in London.
“That makes it very easy to overlook a symptom that would otherwise have caused concern.”
According to Cancer Research UK, around a third (32 percent) of people who noticed a possible ‘red flag’ symptom of cancer did not contact their GP within six months.
These warning symptoms include night sweats, fatigue, persistent itching, change in appetite and bloating. While they are all likely caused by other health problems and external factors, they can also be a sign of deadly cancer.
And delaying diagnosis can have serious and even fatal consequences, says Dr. Kubes.
“The important distinction is whether there is an obvious explanation,” he said.
Blood cancer is the fifth most common cancer in Britain, but less than half of adults in Britain can name one symptom
“In the case of night sweats, if the room is cool but you repeatedly wake up with your pajamas soaked, that’s different from just feeling clammy on a warm night.”
So when should waking up drenched in sweat be a cause for concern?
Soaking night sweats have been linked to certain forms of blood cancer – a disease that shockingly affects less than half of adults in Britain. name one symptom.
Blood cancers, such as lymphomas, are caused by changes in the DNA in blood cells that cause them to behave abnormally. These cells can continue to multiply, preventing healthy cells from growing and functioning.
More than 40,000 people are diagnosed with the disease in Britain every year.
Although symptoms vary depending on the type of blood cancer, night sweats are one of the most common symptoms, along with fatigue and frequent infections.
‘One or two sweaty nights during a heat wave are rarely a reason to panic. However, if unexplained night sweats persist regularly for more than two or three weeks, it would be wise to make an appointment with your GP,” says Dr Kubes.
‘People should seek advice earlier if the sweating is severe or occurs with other worrying symptoms.
‘Crucially, you don’t have to wait several weeks if you feel significantly unwell.’
Other common symptoms include unexplained bruising, bleeding, or pain in your bones and joints that disrupt your sleep or daily activities, unexplained weight loss, shortness of breath, and itchy skin that does not improve with treatment.
Painless swellings in the neck, armpit or groin are also a cause for concern.
Dr. However, Kubes emphasizes that cancer is far from the most common explanation.
“Night sweats have numerous possible causes, including menopause, anxiety, an overactive thyroid, alcohol and certain medications such as antidepressants, steroids and some painkillers,” he said.
‘Fatigue during a heat wave is also very common. It becomes more concerning if it is severe, prolonged and accompanied by symptoms such as heavy sweating, fever or weight loss.”
Anyone experiencing these symptoms should contact their GP.
Dr. Kubes added: ‘The message is not to panic after a few hot nights. It involves recognizing a persistent and unexplained change, especially if other warning signs are present.
“Don’t simply wait for the weather to cool if the sweating is severe, persistent, or accompanied by other symptoms.”
Britain has been hit by the fifth heat wave this year, with temperatures rising predicted to be achieved 38C (100F) today in some areas.
England is currently under an amber health alert from the UK Health Security Agency (UKHSA). warns of ‘increase in deaths’‘.
Deaths in Britain linked to extreme temperatures in May and June this year were almost double the entire 2025 figure, with 2,877 deaths linked to hot weather.
‘These figures highlight the significant danger that very hot weather can pose to people’s health. This is particularly true for those who are more vulnerable, including older adults and people with underlying medical conditions,” said Dr Ross Thompson, lead environmental and public health researcher at UKHSA.
