Night sweats 

  • Overview

Introduction 

Excessive sweating

People who generally sweat excessively, day and night, may have a condition called hyperhidrosis.

Hyperhidrosis doesn't usually pose a serious threat to a person’s health, but it can be embarrassing and distressing.

Many people with the condition are too embarrassed to seek medical help or believe that nothing can be done to improve their symptoms. However, help is available – for example, lifestyle changes and a prescription antiperspirant may help improve your sweating. 

Read more about hyperhidrosis.

People who suffer night sweats will typically wake in the night to find their bedclothes and bedding drenched, even if their bedroom temperature is cool. This abnormal sweating is annoying, but usually harmless.

However, night sweats can sometimes be a sign of an underlying medical condition, so you should see your GP if they keep happening and you're worried.

In the meantime, you can get a better idea of the possible cause of your night sweats by reading on. However, you should not use this page to diagnose yourself with a condition – always leave that to your doctor.

The medical term for night sweats is nocturnal hyperhidrosis, which literally means 'night-time excessive sweating'.

What is the likely cause?

The main conditions and medications that can cause night sweats are summarised below, although it should be noted that many of these conditions would cause other more specific symptoms as well:

  • the menopause
  • obstructive sleep apnoea, a condition that causes interrupted breathing during sleep 
  • medication – antidepressants and some other psychiatric drugs can sometimes cause night sweats as a side effect, as can aspirin and the steroid drug prednisolone
  • alcohol abuse or drug misuse – especially the use of heroin
  • hypoglycaemia (low blood sugar), which is commonly associated with diabetes and taking insulin  
  • infections – tuberculosis is the most common infection associated with night sweats, but sweating may also be caused by other infections including endocarditis (inflammation of the heart valves), osteomyelitis (a bone infection), abscesses and HIV/AIDS
  • cancer – night sweats can be an early symptom of certain cancers like lymphoma or leukaemia, although this is unusual and cancer would cause other symptoms too, such as unexplained weight loss
  • hormone disorders such as pheochromocytoma and carcinoid syndrome (tumours that cause the body to overproduce hormones) and an overactive thyroid gland
  • gastro-oesophageal reflux disease (GORD), where stomach acid leaks out of the stomach and into the gullet – although night sweats are not a common symptom of this 

There may not be an identifiable cause for your night sweats, and it may just be an annoyance that happens every now and then. When the cause is not known, it is referred to as idiopathic hyperhidrosis.




Page last reviewed: 18/10/2012

Next review due: 18/10/2014

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The 3 comments posted are personal views. Any information they give has not been checked and may not be accurate.

Dalip said on 24 December 2013

Night sweats are also seen in vitamin D deficiency particularly in children

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Oldbill30 said on 17 December 2013

Could eating late at night cause this condition ?. I have noticed that if I do it causes this type of sweating

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ShantiMarie said on 15 August 2013

Night sweats can also be a symptom of Kidney Cancer.
If I had had internet access, and known it could be a cause of cancer, my beloved fiance could be alive today.
The doctors just kept giving him anti-biotics for 6 months.
By the time it was discovered and he'd waited 4-5 weeks to be operated on, it had spread to his lymph, only to return to his lungs a years later.
I wish that this symptom of kidney cancer was better known, as his only other symptom was a cough.
It was finally diagnosed when I insisted he asked his GP for a blood test.

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