Do Some People Sweat Blood?

Sweating blood is an extremely rare phenomenon caused by a condition known as hematohidrosis. It occurs when tiny blood vessels in sweat glands suddenly rupture and seep into sweat. Hematohidrosis may seem alarming (and be distressing for someone who has it) but it is a relatively benign (not harmful) condition thought to be triggered by stress and anxiety.

This article describes the symptoms and causes of bloody sweat and explains how hematohidrosis is diagnosed and treated.

What Are the Symptoms of Hematohidrosis?

Hematohidrosis is an extremely rare but benign condition with few cases reported in the medical literature. The condition can occur differently in different people, with some people experiencing lightly blood-tinged sweat and others having dark red secretions resembling blood.

Hematohidrosis can occur on any part of the body, including the trunk and limbs, but is most common in the following areas:

• Forehead
• Scalp
• Face
• Ears
• Eyes

When the eyes are involved, it can seem as if a person is "crying tears." If mucosal (mucous-secreting) tissues are affected, a person may have nosebleeds or vaginal bleeding.

People with hematohidrosis often report having a headache in advance of a bleeding episode. There may also be pain or tingling sensations at the site of the impending outflow of bloody sweat.

Hematohidrosis is a recurrent condition. People may have bleeding episodes as frequently as 35 times per year or as infrequently as once per year. Most episodes last a few seconds to a few minutes. Some cases may clear spontaneously.

While the loss of blood is minimal, hematohidrosis can cause the skin to become very tender and fragile.

What Causes Bloody Sweat?

Until recently, hematohidrosis was thought by many to be either an urban legend or a misdiagnosis of a more common coagulopathy (bleeding disorder). Only in recent years have scientists begun to recognize hematohidrosis as a unique disease entity and weed out verified cases from questionable ones.

Mechanism for Blood Sweating

While there remains debate as to the cause of hematohidrosis, most experts believe that the symptoms occur when tiny blood vessels (called capillaries) that supply blood to the sweat glands spontaneously rupture. The rupture is accompanied by a simultaneous outpouring of sweat.

With hematohidrosis, a specific type of sweat gland—called an eccrine gland—is most commonly affected. These glands open directly onto the skin, unlike apocrine glands that open into hair follicles. Apocrine glands are also mainly confined to the armpits, groin, and anus, while eccrine glands densely populate most areas of the skin (especially the face, trunk, and limbs).

The trigger for hematohidrosis is believed to be stress. At moments of extreme stress, the body will release a hormone called epinephrine (adrenaline) that not only activates eccrine glands but also causes the constriction (narrowing) of blood vessels.

Under normal circumstances, the passing of stress will cause capillaries to dilate (widen) and return to their normal size. But with hematohidrosis, the vessels dilate to the point of rupture, causing the gland to fill with blood. The gland will then push a mixture of blood and sweat onto the surface of the skin.

How Is Hematohidrosis Diagnosed?

Hematohidrosis can be difficult to diagnose because scientists don't yet understand the cause and mechanisms of the disease. There are no tests that can make or confirm a diagnosis and no established criteria to definitively diagnose the disorder.

Some healthcare providers have used a benzidine test (commonly used to detect blood in stools) to evidence the presence of blood in sweat. A microscopic examination of the sweat may also reveal red blood cells. But these tests only work if a person is having a bleeding episode at the time of the evaluation.

Other tests or imaging studies may be ordered to rule out other possible causes for the symptom, such as:

• Hemophilia (an inherited bleeding disorder)
• Idiopathic thrombocytopenic purpura (a bleeding disorder caused by the lack of platelets)
• Von Willebrand disease (a bleeding disorder caused by the lack of clotting factors)
  
• Chromhidrosis (a rare condition that changes the color of sweat)
• Vasculitis (a group of conditions that cause blood vessel inflammation)
• Munchausen syndrome (an illness that is "made up" )

A skin biopsy may be performed so that a sample of skin can be looked at under the microscope. In people with hematohidrosis, the skin cells will look normal.

How Is Hematohidrosis Treated?

There is no cure for hematohidrosis and no treatments known to control symptoms in all people. Several prescription drugs have proven useful, most notably:

• Beta-blockers: These drugs are used to treat high blood pressure and may help prevent the overdilation of capillaries in eccrine glands. The drug Inderal (propranolol) is one of the more commonly used beta-blockers for people with hematohidrosis.
• Anxiolytics: These prescription drugs are used to treat anxiety and may be useful if the bleeding episodes are frequent and triggered by stress.
• Antidepressants: Anxiety and depression go hand in hand, and antidepressants may be appropriate should stress-related bleeding episodes be frequent.

Relaxation techniques, like meditation and deep breathing exercises, are also sometimes used alongside a form of psychotherapy called cognitive behavioral therapy (CBT). These may be useful in people with frequent stress-related attacks.

Summary

Hematohidrosis is an extremely rare disorder that causes a person to sweat blood. It is a distressing but otherwise benign condition that most often occurs during moments of extreme stress. Few cases have been reported in the medical literature.

Hematohidrosis is thought to occur when blood vessels in sweat glands burst. The disorder is diagnosed based on the exclusion of all other causes. Beta-blocker, antidepressants, anti-anxiety drugs, psychotherapy, and relaxation techniques have all been used to treat hematohidrosis.