Do Some People Really Sweat Blood?

Although bloody sweat—or hematohidrosis—may appear alarming, from a somatic perspective, it is a relatively benign condition. The negative effects of this rare condition are psychosocial, and people with hematohidrosis have trouble interacting with others for fear that they may start bleeding, especially under stressful situations.   

In the literature, there are only a handful of case reports, or accounts, or bloody sweat. There are some hypotheses as to what causes or triggers hematohidrosis, but empirical support is lacking. Furthermore, no evidence-based treatment for hematohidrosis exists. Let’s take a look at the little we do know about sweating blood.

Hematohidrosis happens over intact, unbroken skin without lesions. It usually occurs during times of emotional stress. It can also happen during exercise or sleep. The bloody sweat is perspired from the face and hands. Interestingly, hematohidrosis has also been documented in a 10-year-old girl with hemolacria, another rare condition which results in bloody tears. (This girl experienced bloody sweat and tears.)

Episodes of bloody sweat have been observed to last between one and five minutes. Apparently, the sweat is blood-tinged with a consistency akin to regular sweat.

In addition to medical history, hematohidrosis is diagnosed when red blood cells (i.e., erythrocytes) are observed in bloody sweat under the microscope. Other laboratory measures of blood are within normal limits including complete blood cell count, metabolic panel, and coagulation studies. Moreover, results from physical and gynecological examinations are unremarkable.

Skin biopsies have been done on a few individuals diagnosed with hematohidrosis. The results of these biopsies are inconclusive and inconsistent, with some showing normal histology while others showed congestion of periglandular blood vessels, leakage of blood around dermal capillaries, or red blood cells in the cavities of hair follicles.

One differential—or alternative—diagnosis in patients who present with bloody sweat is factitious disorder. Factitious disorder is a serious psychiatric disorder that involves a patient assuming the sick role, and falsely presenting with illness, injury, or physical symptoms. Similarly, malingering is also considered as a differential diagnosis for hematohidrosis. Importantly, malingering differs from factitious disorder in intention: Malingering is motivated by personal gain. To rule out both factitious disorder and malingering, patients who present with bloody sweat can be clinically monitored for bleeding episodes.

Based on case studies in the literature, it appears that hematohidrosis can exacerbate mental illnesses, such as depression, generalized anxiety disorder, and panic disorder. Sadly, people with this condition isolate themselves from others due to embarrassment and anxiety.

Classically, it’s been proposed that blood vessels surrounding the eccrine sweat glands leak blood into the ducts of these glands due to abnormal constrictions and expansions (i.e., dilatations). Other explanations propose high blood pressure and inflammation of blood vessels (i.e., vasculitis) as causes of bleeding into the eccrine sweat glands.

These hypotheses, however, remain unproven, and similar bleeding occurs from hair follicles as well as in areas sans sweat glands. In fact, in the literature, a few patients have presented with blood-tinged otorrhea, or ear drainage.

In a 2015 article titled “Hematohidrosis: insights in the pathology,”  Uber and colleagues write the following regarding hematohidrosis:

"Some theories have been proposed, including: increased vascular pressure leading to the passage of blood cells through the ducts of the sweat glands; vasculitis of dermal vessels; and exacerbated sympathetic activation leading to periglandular vessel constriction and subsequent expansion, allowing the passage of blood content into the ducts."

In this article, Uber and colleagues were the first to document a link between hypertensive episodes and hematohidrosis. Using 24-hour ambulatory blood pressure monitoring, the researchers observed that blood pressure readings in an 18-year-old white woman peaked to 180/90 during bleeding episodes.

There’s no proven way to treat hematohidrosis. Propanolol, which is a beta-blocker used to treat high blood pressure, has helped some people with this condition. The reason why beta-blockers are effective in the treatment of hematohidrosis may have to do with the fact that sympathetic innervation, which is targeted by beta-blockers, probably plays a role in this condition.