What are the causes of night sweats?

Causes of Night Sweats

Night sweats have multiple etiologies, with menopause being the most common hormonal cause in women, while tuberculosis and lymphoma remain critical infectious and malignant causes that must be systematically excluded through targeted evaluation.

Primary Etiologic Categories

Hormonal and Physiologic Causes

• Menopause is the most frequent hormonal cause in women, characterized by recurrent episodes of flushing, perspiration, and intense heat sensations on the upper body and face, sometimes followed by chills 1
• Menopausal symptoms affect approximately 46-73% of female cancer survivors and 50-80% of men receiving androgen deprivation therapy 2
• Hyperthyroidism represents another important hormonal cause that should be evaluated 3, 4
• Hypogonadism in aging males is a rarer cause and must be associated with sexual dysfunction and repeatedly low morning testosterone levels 4

Infectious Causes

• Tuberculosis is a significant infectious cause, especially when accompanied by persistent cough, weight loss, loss of appetite, or fever 5, 3
• Tuberculin skin test or interferon-gamma release assay should be performed in high-risk patients, including those with TB contact history, residence in high-prevalence areas, or HIV infection 5
• HIV infection itself can cause night sweats and requires testing in high-risk individuals 5, 6

Malignant Causes

• Lymphoma commonly presents with night sweats, particularly when accompanied by weight loss, fever, and lymphadenopathy (B symptoms) 3
• Other malignant tumors may cause night sweats, though tuberculosis and lymphoma remain the dominant disease-associated causes 7

Other Medical Conditions

• Gastroesophageal reflux disease (GERD) is a frequently overlooked cause in primary care 7, 6
• Obstructive sleep apnea should be considered, particularly in patients with sleep disruption 7
• Autoimmune diseases, including various rheumatic and musculoskeletal conditions, can present with night sweats 1
• Hypoglycemia may cause nocturnal sweating episodes 7
• Mood disorders and panic attacks are common causes that should be explored when patients report night sweats 6, 4

Medication-Induced Causes

• Antihypertensives and antipyretics are common pharmacologic causes 7
• Serotonin reuptake inhibitors can cause night sweats (alpha-adrenergic blockers may reduce this side effect) 8
• Drugs of abuse, including alcohol and heroin, may trigger night sweats 7

Diagnostic Approach

Initial History and Physical Examination

• Determine frequency, severity, and impact on quality of life of the night sweats 1
• Assess for associated symptoms: weight loss, fever, persistent cough, fatigue, lymphadenopathy 5, 3, 1
• Evaluate tuberculosis risk factors: contact history, origin from high-prevalence areas, HIV status 5, 3
• Review medication history and substance use 7
• In women, assess menopausal status and timing relative to last menses 2

Laboratory and Imaging Studies

When history and physical examination do not reveal a specific cause, proceed with:

• Complete blood count to evaluate for hematologic malignancies 7, 6
• Tuberculin skin test or interferon-gamma release assay in high-risk patients 5
• HIV testing in appropriate populations 5, 6
• Thyroid-stimulating hormone (TSH) to exclude hyperthyroidism 7, 6
• C-reactive protein or erythrocyte sedimentation rate as inflammatory markers 7, 6
• Chest radiograph as initial imaging 7, 6

Additional Selective Testing

• Chest and/or abdominal CT scans if malignancy is suspected 7, 6
• Bone marrow biopsy if hematologic malignancy remains a concern 7, 6
• Polysomnography if obstructive sleep apnea is suspected 6
• Intestinal tuberculosis PCR and biopsy in patients with gastrointestinal symptoms suggesting intestinal TB 5

Important Clinical Considerations

Reassuring Prognostic Information

• Life expectancy of primary care patients reporting night sweats does not appear to be reduced 8
• The presence of night sweats alone does not indicate an increased risk of death 6
• Prevalence ranges from 10% in older primary care patients to 60% in hospitalized obstetric patients, indicating this is a common, often benign symptom 8

Special Populations

• HIV patients with night sweats require more aggressive tuberculosis evaluation given diagnostic challenges in this population 3
• Cancer survivors on aromatase inhibitors or androgen deprivation therapy commonly experience night sweats as treatment-related menopausal symptoms 2
• Postmenopausal women should have other causes ruled out, particularly hyperthyroidism, before attributing symptoms solely to menopause 3

Clinical Pitfalls

• Many suggested clinical causes are not well-supported by evidence, and algorithmic approaches to evaluation lack evidence-based validation 8
• Night sweats appear to be a nonspecific symptom, and most primary care patients reporting persistent night sweats do not have a serious underlying disorder 8, 6
• If initial evaluation with readily available tests is normal and no additional disorders are suspected, reassurance and continued monitoring are appropriate 6