blood
The doctors eventually diagnosed the patient as having an incredibly rare condition called hematohidrosis, which is known to cause blood to spontaneously ooze out from intact skin iStock

A mysterious and rare condition has caused a woman to spontaneously sweat blood from her face and palms for years, in a case that reportedly left doctors baffled. A 21-year-old Italian woman, without any injuries or skin lesions, reported to doctors that over the past three years, she has been sweating blood spontaneously in episodes that lasted between one to five minutes. The woman reported that the bleeding would often begin during some physical activity or even during sleep, with intensifying bouts when she was stressed.

The rare condition was published as a case study in the Canadian Medical Journal. Doctors Roberto Maglie and Marzia Caproni wrote that the patient reported symptoms of depression, self-isolation and panic disorder. The doctors eventually diagnosed the patient as having an incredibly rare condition called hematohidrosis, which is known to cause blood to spontaneously ooze out from intact skin.

The patient was treated with beta blockers and antidepressents. Although the drugs reduced some of the episodes of blood sweating, it was not completely stopped.

Although the condition has been medically reported for centuries, dating back to the writings of Aristotle, some experts have previously been sceptical of its existence. According to Dr Jacalyn Duffin, a medical historian and hematologist at Queen's University in Kingston, Ontario, who wrote a commentary accompanying the case report, there have only been around 12 similar cases reported across the globe over the past 15 years. "Credible, though scant, observations of sweating blood persist" in medical literature, she wrote in her commentary. "This collection of well-documented observations commands respect and acceptance."

No one knows what causes the condition

According to Duffin, little is known about the condition, apart from the manifesting symptoms. The likely causes of the bleeding as well as any methods to stop it, still remain a mystery.

Duffin wrote that description of "blood sweat" date as far back as the third century BC. Although in some cases they were reported during the late medieval era, the references were made alongside Christianity and the crucifixion of Christ. However, from the 1600s onwards, Duffin says that "eyewitness accounts" of the condition began appearing in medical literature.

In more recent years, five cases of blood sweating have been reported in 2013, four in 2014, three in 2015, four in 2016 and two so far in 2017.

"In other words, almost half the total output from more than a century came in the last five years. Is the incidence of this condition increasing? Is it being more frequently recognized, as other causes or diagnoses are identified and eliminated?" Duffin wrote. "But why — with all this evidence — do we still harbour doubts about its existence? Other rare conditions are not viewed with similar scepticism. Ironically, for an increasingly secular world, the long-standing association of hematohidrosis with religious mystery may make its existence harder to accept. It seems that humans do sweat blood, albeit far less often literally than metaphorically."