Night sweats - red flag symptoms

Possible causes of night sweats, including questions to ask during consultations and suitable examinations and investigations.

Red flag symptoms

  • Significant unintentional weight loss
  • Any symptoms warranting a two-week wait referral
  • A history of foreign travel
  • Risk factors for HIV
  • Palpable lymph glands
  • Risk factors for TB
  • Recurrent bacterial infections requiring antibiotics
  • History of alcohol excess or recreational drug use
  • Signs of meningeal irritation (meningism), such as neck stiffness, photophobia, headache
  • Haemoptysis

Night sweats are not a common problem, but may be discovered when exploring other concerns or on a systemic review. There is a broad range of differential diagnoses to consider.

Night sweats can be a nonspecific problem, so establishing a cause can be difficult. It is important to find out what the patient means by night sweats and explore what effect they are having. Night sweats requiring patients to change clothing or bed linen should be taken seriously.

Night sweats can be a manifestation of simple infection, underlying malignancy, more complex infections including TB and HIV, connective tissue disorders, menopause or certain prescribed drugs.

Questions to consider

  • How long have the night sweats been a problem?
  • How do they bother the patient?
  • What does the patient feel the problem could be?
  • Has the patient noticed any appetite loss or weight loss?
  • Has the patient had any unexplained persistent fever?
  • Has the patient measured their temperature during the episodes? If so, what is it?
  • Has the patient had any other red flag symptoms, such as persistent cough, dyspnoea, haemoptysis, change in bowel habit, rectal bleeding, haematuria, joint stiffness, swelling or deformity, lumps suggestive of lymph nodes, breast lumps, testicular lumps or postmenopausal bleeding (if relevant)?
  • As lymphadenopathy can affect the neck, axilla and inguinal region, then ask about swelling in these specific areas, if you suspect lymphadenopathy.
  • If you suspect that your patient is menopausal, then consider asking about other vasomotor symptoms, such as hot flushes, urogenital symptoms, such as vaginal dryness, or mood disturbance
  • Ensure you are familiar with the patient’s medications. Certain medications can cause hot flushes, for example hormonal treatments for prostatic cancer
  • Is there a significant alcohol history or history of recreational drug use?
  • Do they smoke? This maybe relevant if malignancy is suspected but also may exacerbate the symptom
  • You may wish to enquire about depressive or anxiety-type symptoms

It may be important to know if the patient has a history of foreign travel if TB or another infectious disease is suspected. Consider HIV if there are risk factors for this. Risk factors include blood transfusions, IV drug use, tattoos or same-sex partners.

Possible causes
  • Simple infection
  • Malignancy
  • Complex infections - TB, HIV
  • Menopause
  • Prescribed drugs
  • Anxiety


Examination will be guided by the history. If appropriate, check the patient's temperature. Do they look cachectic? It may be useful to weigh them.

If malignancy is suspected, examination of the affected system will be necessary. Auscultate and percuss the chest to exclude evidence of pneumonia or effusion.

Check the abdomen for masses, for example hepatosplenomegaly. It may also be necessary to check palpable lymph nodes, for example cervical, axillary or inguinal nodes.


Investigations will be guided by the history and examination findings.

  • Routine blood tests - FBC, U&Es, LFTs, CRP, ESR, HIV, TSH, autoimmune screen
  • Sputum culture and sensitivity
  • Stool cultures may be relevant. If you suspect infective diarrhoea as a cause, you may require three samples on three separate days to increase the likelihood of catching the infection
  • Plain chest X-ray
  • Ultrasound of the abdomen and pelvis may be necessary
  • Ultrasound soft tissue if you find lymph nodes
  • HADS score if you suspect anxiety

Other investigations such as CT, MRI or bone scans may require secondary care referral via the appropriate pathway. More complex elderly patients may require referral to rapid access elderly care service. Testing for tumour markers is not recommended in primary care.

Any red flag symptoms may require appropriate investigations under the two-week rule depending on the rest of the history, examination findings and preliminary investigations.

Pyrexia of unknown origin may require assessment by your local infectious diseases team.

Management will largely depend on the cause of the problem.

  • Dr Singh is a GP in Northumberland

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This is an updated version of an article first published in August 2013

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