Mythology and religious texts are full of stories of leaders and heroes sweating blood. This phenomenon is not just fantasy, however, but very real. As well as bloody sweat, people can ooze blood from their eyes, nose, and other mucous membranes in a condition known as hematidrosis.

Most studies suggest that stress and involuntary nervous system reactions cause hematidrosis or bloody sweat. Hematidrosis is also sometimes called hematohidrosis or hemidrosis.

Hematidrosis is not a medical condition, so treatment focuses on determining the underlying cause.

Fast facts on hematidrosis:

  • Hematidrosis remains mysterious due to its rare occurrence.
  • Hematidrosis is so rare that studies on it usually focus on a single case.
  • Research suggests that tiny blood vessels that cause bloody sweat are more likely to rupture under intense stress. The stress can be physical, psychological, or both.
  • Treatment depends on the underlying cause.

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Hematidrosis is a medical complication characterized by the person appearing to sweat blood, or blood oozing from mucus membranes.

Hermatidrosis is extremely rare, which makes it difficult for doctors to research the condition.

The condition may manifest differently in every individual. This makes it difficult for doctors to offer clear prognoses or test which treatments are most effective.

A case study published in 2013 gathered data on an 18-year-old woman with hematidrosis. For 6 months, she experienced bleeding from the forehead, eyes, hands, navel, and fingernails. All laboratory and other tests were normal, though the frequency of the bleeding increased over time.

While hospitalized, the woman experienced 30 distinct bleeding episodes. Doctors were never able to diagnose or treat the cause of the bleeding, but 20 months after her diagnosis, the bleeding had greatly decreased.

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Hematidrosis can originate from various parts of the body, such as the forehead, eyes, ears, or belly button.
Image credit: Saugato Biswas, Trupti Surana, Abhishek De, and Falguni Nag, (2013, October 17).

Bleeding occurs when tiny blood vessels rupture. Some blood vessels, including those near the sweat glands and in mucous membranes, are closer to the skin’s surface. This makes them more likely to rupture. It also explains why hematidrosis is more common near the nose, forehead, and other parts of the body located near sweat glands or mucous membranes.

Physical and psychological stresses are suspected of causing the condition. This theory might explain why reports on religious figures often highlight stories of bloody sweat. In biblical mythology, for example, Jesus purportedly sweats blood while praying in anticipation of his crucifixion and death. This apparently miraculous occurrence could be little more than intense stress causing blood vessels to rupture.

Although stress likely plays a role, it cannot fully explain this phenomenon. Rates of stress, anxiety disorders, and other mental health conditions have increased in recent years, yet hematidrosis has not. This suggests that other abnormalities may play a role.

People with a history of hematidrosis may have defects in the dermis, the layer of skin beneath the outer layer. This hypothetical skin defect could provide space for blood to accumulate, making it possible to sweat blood.

However, not all cases of bloody sweat are attributable to physical or emotional stress. A 2013 case study details the story of a 12-year-old girl with hematidrosis. The girl had no bleeding disorders, no apparent other medical conditions, and no history of psychological problems or stress. Each bleeding episode lasted 10-15 minutes and did not appear to upset the girl.

Doctors treated her with atropine, a drug that blocks certain functions of the involuntary nervous system. Over time, her symptoms decreased, and she received no other treatment. The underlying cause of her symptoms remains a mystery.

It is common for doctors to find no underlying cause for hematidrosis. Some other studies have found that nervous system issues may play a role in hematidrosis

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Various tests may be performed to diagnose the cause of hematidrosis, including biopsies, blood tests, and brain scans.

Doctors normally perform a wide variety of tests, including:

  • blood tests to see if platelet and red and white blood cell counts are normal
  • biopsies of the affected area to test for abnormal cells
  • testing for various infections
  • psychological testing
  • neurological testing, including brain scans

Alleviating the immediate cause of the physical or emotional stress often also stops the bleeding. All other treatments are experimental, since the number of people with hematidrosis is too small to prove the effectiveness of any single treatment.

Some research suggests that beta-blockers, a group of drugs that reduce high blood pressure, can slow or stop the bleeding of hematidrosis.

Hematidrosis rarely causes serious side effects, though some people experience dehydration and anxiety. Doctors may give additional medication to treat these symptoms. Psychological counseling can also help if a person with hermatidrosis has depression and anxiety.

Because hematidrosis is so rare, it is common for doctors to ask people with hematidrosis to stay in the hospital for observation.

Bloody sweat can be terrifying. For some people, even the notion that it is possible to sweat blood can be unnerving. However, hematidrosis is not typically dangerous.

The blood comes from small blood vessels located near the skin’s surface, not deep veins or arteries. This makes it virtually impossible to bleed to death from hematidrosis.

Even people experiencing hematidrosis across many areas of the body are at virtually no risk of bleeding to death though they may experience dizziness, anxiety, and moderate dehydration.

Because hematidrosis involves blood mixing with sweat, people with this syndrome may appear to be bleeding much more than they are. The watered-down blood looks more significant than it is, and the startling sudden appearance of blood may trigger fears that something is seriously wrong.

Hematidrosis is not associated with or a symptom of any life-threatening medical conditions. The bleeding usually stops on its own, and even without treatment, symptoms may disappear over time.