Yes, humans can literally sweat blood. The condition is called hematidrosis, and it’s one of the rarest phenomena in medicine. Droplets of blood, or blood mixed with sweat, seep through intact skin during moments of extreme emotional or physical stress. Episodes typically last only a few minutes and stop on their own.
How Blood Ends Up in Your Sweat
Tiny blood vessels called capillaries surround every sweat gland in your body. Under intense stress, your sympathetic nervous system (the same system behind the fight-or-flight response) fires hard enough to first constrict and then rapidly dilate those capillaries. During that dilation phase, some capillaries around the sweat glands rupture. Blood leaks into the sweat ducts and gets pushed to the skin’s surface along with normal sweat, appearing as pink or red droplets on otherwise undamaged skin.
The fluid isn’t pure blood. When examined under a microscope, it contains red blood cells mixed with sweat components. The color ranges from pale pink to deep red depending on how much blood is in the mix.
What Triggers It
Extreme psychological stress is the most common trigger by a wide margin. Documented cases include people condemned to execution, a person living through the London Blitz bombing raids, someone facing the threat of sexual assault, and a sailor caught in a terrifying storm. In one well-documented case, a man who had endured two years of continuous family conflict was diagnosed with both hematidrosis and depression.
Beyond acute fear, other reported triggers include intense physical exertion, certain systemic diseases, and psychosomatic disorders. In some cases, no clear trigger is ever identified. There’s also a curious subset of cases in women where bloody sweating occurs in sync with the menstrual cycle, a phenomenon called vicarious menstruation.
Where It Appears on the Body
More than 75% of documented patients bleed from multiple sites on the body. The forehead and ears are the most frequently affected areas overall. Men tend to bleed from their limbs and forehead, while women more often bleed from the eyes and ears. In one case, a 16-year-old girl experienced recurring bloody discharge from her right ear three to five times per week, with each episode resolving within minutes.
How Rare It Actually Is
Hematidrosis is extremely rare. A 2024 review of all published pediatric cases worldwide found just 25 children documented in the entire medical literature. The majority of reported cases (56%) come from India, with smaller numbers from Turkey, Bangladesh, South Africa, China, Thailand, Brazil, and Tunisia. Only a single case has been reported from Europe. The true number of people affected is unknown, partly because the condition is so unusual that many doctors have never encountered it.
How Doctors Confirm the Diagnosis
There’s no single test that immediately confirms hematidrosis. Doctors arrive at the diagnosis through a process of elimination, ruling out bleeding disorders, skin conditions, and external contamination first. Standard blood work, clotting tests, and platelet function tests all come back normal in hematidrosis patients, which is part of what makes it so puzzling.
The key confirmatory step is testing the fluid itself. A chemical test called the benzidine test detects hemoglobin in the secretion. When the fluid is examined under a microscope, it shows red blood cells mixed with sweat. Biochemical analysis confirms components of both blood and sweat are present.
Conditions That Can Look Similar
A few other conditions produce colored sweat and need to be distinguished from hematidrosis:
- Chromhidrosis: Colored sweat (often yellow, green, blue, or black) caused by pigment-producing cells in the apocrine sweat glands. The sweat is colored but doesn’t contain blood.
- Pseudochromhidrosis: Normal, colorless sweat that picks up color after it reaches the skin’s surface, usually from bacteria, dyes, or chemicals on the skin.
- Eccrine chromhidrosis: Sweat that becomes colored after ingesting certain drugs or dyes, including some antibiotics and food additives.
Treatment and Outlook
Because stress drives most cases, treatment focuses on calming the body’s overactive stress response. Beta-blockers, particularly propranolol, have emerged as the most effective option. A systematic review of 20 studies found that propranolol improved symptoms in over 75% of patients. Treatment courses ranged from one week to six months, with doses tailored to each individual.
The condition doesn’t appear to cause lasting skin damage or systemic health problems. Blood work in affected patients consistently shows normal organ function, normal clotting ability, and no underlying blood disorders. The main complications are psychological: the distress of visibly bleeding through your skin, the anxiety that can both trigger and be worsened by episodes, and the challenge of having a condition so rare that many people (including some doctors) don’t believe it exists.
Addressing the underlying stressor, whether through psychiatric treatment for depression or anxiety, removal from a stressful situation, or therapy, is considered just as important as medication. In many documented cases, episodes become less frequent once the triggering stress is managed.