Night sweats (NS) is a common patient complaint, affecting about a third of hospitalized patients on medical wards¹.  Despite its long list of potential causes, direct relationship between the often- cited conditions and NS is usually unclear², its cause may remain elusive In about a third to half of cases in the primary care setting, and its prognosis, at least in those >65 y of age, does not appear to be unfavorable ^2,3.

Selected commonly and less frequently cited conditions associated with NS are listed (Table)^2-9.  Although tuberculosis is one of the first conditions we think of when faced with a patient with NS, it should be emphasized that NS is not common in this disease (unless advanced) and is rare among hospitalized patients as a cause of their NS^1,9.

In one of the larger study of adult patients seen in primary care setting, 23% reported pure NS and an additional 18% reported night and day sweats⁵; the prevalence of NS in both men and women was highest in 41-55 y age group. In multivariate analyses, factors associated with pure NS in women were hot flashes and panic attacks; in men, sleep disorders. 

Table. Selected causes of night sweats

Commonly cited	Less frequently cited
Neoplastic/hematologic (eg, lymphoma, leukemia, myelofibrosis) Infections (eg, HIV, tuberculosis, endocarditis) Endocrine (eg, ovarian failure, hyperthyroidism, orchiectomy, carcinoid tumor, diabetes mellitus [nocturnal hypoglycemia], pheochromocytoma) Rheumatologic (eg, giant cell arteritis)	Gastroesophageal reflux disease B-12 deficiency Pulmonary embolism Drugs (eg, anti-depressants, SSRIs, donepezil [Aricept], tacatuzumab) Sleep disturbances (eg, obstructive sleep apnea) Panic attacks/anxiety disorder Obesity Hemachromatosis Diabetes insipidus

References

1. Lea MJ, Aber RC, Descriptive epidemiology of night sweats upon admission to a university hospital. South Med J 1985;78:1065-67.
2. Mold JW, Holtzclaw BJ, McCarthy L. Night sweats: A systematic review of the literature. J Am Board Fam Med 2012; 25-878-893.
3. Mold JW, Lawler F. The prognostic implications of night sweats in two cohorts of older patients. J Am Board Fam Med 2010;23:97-103.
4. Mold JW, Holtzclaw BJ. Selective serotonin reuptake inhibitors and night sweats in a primary care population. Drugs-Real World Outcomes 2015;2:29-33.
5. Mold JW, Mathew MK, Belgore S, et al. Prevalence of night sweats in primary care patients: An OKPRN and TAFP-Net collaborative study. J Fam Pract 2002; 31:452-56.
6. Feher A, Muhsin SA, Maw AM. Night sweats as a prominent symptom of a patient presenting with pulmonary embolism. Case reports in Pulmonology 2015. http://dx.doi.org/10.1155/2015/841272
7. Rehman HU. Vitamin B12 deficiency causing night sweats. Scottish Med J 2014;59:e8-11.
8. Murday HK, Rusli FD, Blandy C, et al. Night sweats: it may be hemochromatosis. Climacteric 2016;19:406-8.
9. Fred HL. Night sweats. Hosp Pract 1993 (Aug 15):88.