Pearl of the Month

Night sweats

Publish date: November 30, 2018

A 46-year-old man comes to clinic for evaluation of night sweats. He has been having drenching night sweats for the past 3 months. He has to change his night shirt at least once per night. He has had a 10-pound weight gain over the past 6 months. No chest pain, nausea, or fatigue. He has had a cough for the past 6 months.

Which is the most likely diagnosis?

A. Gastroesophageal reflux disease.

B. Tuberculosis.

C. Lymphoma.

D. Multiple myeloma.

Night sweats are a common symptom in the general population, estimated to occur in about 10% of people. They can range in frequency and severity. We become most concerned when the patient is concerned, usually when they report drenching night sweats.

Dr. Douglas S. Paauw

Two diagnoses that most people think of when they hear night sweats are lymphoma and tuberculosis. These make up a tiny minority of diagnosis of night sweats, however. In the absence of other features suggestive of these diseases, including alarm features such as weight loss, these two diagnoses should not be aggressively pursued.

What do we need to know about this symptom to help us think of more likely causes and guide us in a more appropriate workup?

Night sweats do not seem to be a bad prognostic symptom. James W. Mold, MD, and his colleagues looked at the prognostic significance of night sweats in two cohorts of elderly patients.¹ The prevalence of night sweats in this study was 10%. These two cohorts were followed for a little more than 7 years. More than 1,500 patients were included in the two cohorts. Patients who reported night sweats were not more likely to die, or die sooner, than were those who didn’t have night sweats. The severity of the night sweats did not make a difference.

Lea et al. described the prevalence of night sweats among different inpatient populations, with a range from 33% in surgical and medicine patients, to 60% on obstetrics service.²

Night sweats are common, and don’t appear to be correlated with worse prognosis. So, what are the likely common causes?

There just aren’t good studies on causes of night sweats, but there are studies that suggest that they are seen in some very common diseases. It is always good to look at medication lists as a start when evaluating unexplained symptoms.

Dr. Mold, along with Barbara J. Holtzclaw, PhD, reported higher odds ratios for night sweats for patients on SSRIs (OR, 3.01), angiotensin receptor blockers (OR, 3.44) and thyroid hormone supplements (OR, 2.53).³ W.A. Reynolds, MD, looked at the prevalence of night sweats in a GI practice.⁴ A total of 41% of the patients reported night sweats, and 12 of 12 patients with GERD who had night sweats had resolution of the night sweats with effective treatment of the GERD.

Dr. Mold and his colleagues found that night sweats were associated with several sleep-related symptoms, including waking up with a bitter taste in the mouth (OR, 1.94), daytime tiredness (OR, 1.99), and legs jerking during sleep (OR, 1.87).⁵

Erna Arnardottir, PhD, and her colleagues found that obstructive sleep apnea was associated with frequent nocturnal sweating.⁶ They found that 31% of men and 33% of women with OSA had nocturnal sweating, compared with about 10% of the general population. When the OSA patients were treated with positive airway pressure, the prevalence of nocturnal sweating decreased to 11.5%, similar to general population numbers.

Pearl: Night sweats are associated with common conditions: medications, GERD, and sleep disorders. These are more likely than lymphoma and tuberculosis.

Dr. Paauw is professor of medicine in the division of general internal medicine at the University of Washington, Seattle, and serves as third-year medical student clerkship director at the University of Washington. Contact Dr. Paauw at dpaauw@uw.edu.