Night sweats and unintentional weight loss are common symptoms with many possible causes, most of them benign. Anxiety, hormonal changes and viral infections are far more common explanations than cancer. When the symptoms persist for more than two to three weeks without a clear cause, a CT chest scan excludes the less common thoracic causes: lung cancer, lymphoma, pleural infection and tuberculosis. Dr Lawrence Okiror, Consultant Thoracic and Robotic Surgeon (GMC 6150382), investigates thoracic causes at London Bridge Hospital. Where cancer is found, every case is discussed with a specialist team before any decision is made. Private appointments within 2–3 days. Self-referrals welcome.
Last reviewed: October 2026 · Dr Lawrence Okiror FRCS(CTh) FRCSEd(CTh) · GMC 6150382
The most common causes of night sweats are anxiety, hormonal changes and viral infections, all manageable and all far more frequent than cancer. Unintentional weight loss is most often caused by poor appetite from another illness, infection or inflammatory disease.
When night sweats are drenching, have persisted for two to three weeks, and are accompanied by unintentional weight loss without a clear cause, a CT chest scan is the right investigation. It either gives reassurance or finds something treatable at an earlier stage.
Where a thoracic cancer is found while constitutional symptoms are the main complaint, the disease is often at an earlier stage than when breathlessness or pain develop. Earlier means more treatment options and a better chance of complete treatment.
Four thoracic conditions can present with night sweats and weight loss as prominent early symptoms. All four are identifiable on a CT scan and all four are treatable.
Lung cancer can cause night sweats and weight loss as early symptoms, sometimes before breathlessness or cough become prominent. Finding it at a stage where constitutional symptoms are still the main complaint means surgery and targeted therapies are more likely to be possible. If a scan has already shown a shadow or nodule, the shadow on a lung scan page explains what happens next. Lung nodule & cancer →
Lymphoma affecting the chest or mediastinum is one of the classic causes of drenching night sweats, weight loss and fatigue, known together as B symptoms. CT identifies enlarged lymph nodes; a mediastinal lymph node biopsy confirms the diagnosis and the subtype. What a finding in the middle of the chest means is covered on the mediastinal finding on a scan page. Lymphoma is highly treatable, particularly at earlier stages.
An infected fluid collection in the pleural space (an empyema) causes night sweats, fever and weight loss alongside chest pain, and often follows a chest infection that has not fully resolved. Drainage and antibiotics treat most cases; keyhole surgery clears the infection when they do not. Empyema & pleural infection →
TB classically causes night sweats, weight loss, fatigue and a persistent cough, and it remains a relevant diagnosis in London. CT and sputum tests identify it, and it is treated with antibiotics. Where surgery is needed alongside antibiotic treatment, for a fungal ball in an old TB cavity or persistent bleeding for example, Dr Okiror works with the respiratory medicine or infectious disease team. Lung infection surgery →
For GPs: the NICE threshold
NICE guideline NG12 recommends an urgent chest X-ray, within two weeks, for anyone aged 40 or over with two or more unexplained symptoms from cough, fatigue, shortness of breath, chest pain, weight loss and appetite loss, or with one of them if they have ever smoked. Unexplained weight loss in a current or former smoker therefore meets the threshold on its own. Where the X-ray is normal and the symptoms persist, a CT chest scan is the next step; Dr Okiror sees these patients within 2–3 days and reviews any existing imaging at the first appointment. Referral details are on the For GPs page.
Every cancer case is discussed with a multidisciplinary team of specialist oncologists at the London Bridge Hospital chest MDT, which Dr Okiror attends fortnightly. Where a case needs urgent discussion, Dr Okiror has direct access to the same specialist colleagues outside the formal meeting, so an urgent decision is not held over to the next MDT. No treatment plan is made by a single doctor alone.
Questions most commonly asked by patients experiencing persistent night sweats and unexplained weight loss.
Book an Assessment →Jo Mitchelson, PA
020 7952 2882
pa@lungsurgeon.co.uk
Self-referrals welcome. Private appointments at London Bridge Hospital within 2–3 days. Dr Okiror reviews all findings personally and gives you a clear answer and a clear plan.
Jo Mitchelson, PA · 020 7952 2882 · pa@lungsurgeon.co.uk
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A cough lasting more than three weeks without a clear explanation, and when it needs a specialist opinion
Coughing Up BloodHaemoptysis always needs prompt assessment; most causes are treatable
BreathlessnessWhen breathlessness needs a thoracic opinion, and the surgical causes that can be treated
Unexplained Chest PainChest pain after the heart and lungs have been cleared: the chest wall, pleural and rib causes
Shadow on a Lung ScanWhat a shadow or nodule on a chest X-ray or CT can mean, and how it is investigated
A Finding in the Middle of the ChestWhat a mediastinal finding on a scan means, including enlarged lymph nodes and lymphoma
Lung Infection SurgerySurgery for localised bronchiectasis, aspergilloma, lung abscess and TB, by specialist referral
Empyema & Pleural InfectionInfected fluid around the lung: drainage, antibiotics and keyhole surgery when they are not enough
Specialist Second OpinionIndependent review of your scans, blood tests and the plan, within 2–3 days