If you notice that your blood is an unusual purple color, it can be alarming. However, there are a few potential causes for purple blood that are worth exploring.
Quick Answer Summary
In most cases, purple blood is caused by a rare condition called sulfhemoglobinemia, where sulfur atoms bind to the iron in hemoglobin. This prevents hemoglobin from carrying oxygen effectively, causing a purplish hue to the blood. Less common causes include dyes or infections. Treatment depends on the underlying cause but may include medications, blood transfusions, or oxygen therapy.
What Causes Purple Blood?
Here are some of the most common potential causes for purple-colored blood:
Sulfhemoglobinemia
Sulfhemoglobinemia is a rare condition where sulfur atoms bind to the iron in hemoglobin, preventing it from carrying oxygen effectively. This causes a purple hue to the blood and symptoms like shortness of breath, headaches, and cyanosis (blue tint to skin). It can be congenital or acquired through sulfur drug exposure or infections.
Dyes and Food Coloring
Ingesting large amounts of dyes or food coloring can sometimes tint the blood a purple shade. This is often seen in medical students or anatomy lab workers exposed to preserving dyes. The discoloration is harmless and clears quickly when the exposure stops.
Bacterial Infections
Certain bacterial infections, like endocarditis or sepsis, can also turn blood purple. Bacteria produce sulfur-containing compounds that bind to hemoglobin, inducing sulfhemoglobinemia. Infections need antibiotic treatment.
Methemoglobinemia
Methemoglobinemia is similar to sulfhemoglobinemia but is caused by iron being oxidized rather than bound to sulfur. Risk factors include anemia, nitrate toxicity, and genetic enzyme deficiencies. It requires different treatment but also causes purple blood.
Polycythemia Vera
Polycythemia vera, a rare bone marrow disorder, results in overproduction of red blood cells. The excessive concentration of red blood cells can create a dark purplish tint to the blood.
Medications and Toxins
Exposure to certain medications, like dapsone, nitrates, or aniline dyes, can also oxidize hemoglobin and induce methemoglobinemia. Recreational drugs like amyl nitrate have similar effects. Removing the substance reverses this cause.
Congenital Heart Defects
Some severe congenital heart defects, like transposition of the great arteries, can restrict oxygenation of blood and give it a dusky purple color. These require surgical correction.
When to See a Doctor
Purple blood is always abnormal and merits medical evaluation. Seek urgent care if you notice purple blood along with:
- Shortness of breath or trouble breathing
- Headache, dizziness, or fainting
- Chest pain
- Cyanosis – blueish lips, skin, or nail beds
- Severe infection symptoms like high fever
Call 911 or go to an emergency room if you have severe symptoms like loss of consciousness, seizure, or suffocation.
Diagnosing Purple Blood
Doctors can use several tests and exams to diagnose what’s causing purple blood:
Physical Exam
Checking for cyanosis in skin, lips, or tongue. Listening to heart and lungs.
Blood Tests
Measuring levels of hemoglobin, sulfhemoglobin, and methemoglobin. Blood cultures if infection.
Pulse Oximetry
A device that measures oxygen saturation of blood, which may be low.
Blood Gas Analysis
Measures blood pH and oxygen and carbon dioxide levels.
Imaging
Chest x-ray or CT scan to assess for underlying lung issues or heart defects.
| Test | Purpose |
|---|---|
| Physical exam | Check for cyanosis and listen to heart/lungs |
| Blood tests | Measure hemoglobin types and oxygen capacity |
| Pulse oximetry | Measure blood oxygen saturation |
| Blood gas analysis | Assess blood pH, oxygen, and carbon dioxide levels |
| Imaging | X-rays or CT scans to examine lungs and heart |
Treating Purple Blood
Treatment depends on the underlying cause of the purple blood:
Sulfhemoglobinemia
- Oxygen therapy
- Blood transfusion in severe cases
- Medications like methylene blue or vitamin C to counteract sulfhemoglobin
- Discontinuing any sulfur drugs
- Treating infections with antibiotics
Methemoglobinemia
- Stopping the causative drug or toxin
- Methylene blue injections to restore iron oxidation
- Oxygen therapy
- Blood transfusion for severe cases
Dyes or Food Coloring
- Removing the exposure and waiting for discoloration to clear
- Activated charcoal to absorb remaining dye
Bacterial Infections
- Antibiotics to treat the infection
- Oxygen therapy and ventilation support if needed
Congenital Heart Defects
- Surgical repair to correct the abnormal circulation
- Medications to help manage heart failure symptoms
In most cases, purple blood is reversible once the underlying condition is treated. However, immediate medical care is important to prevent complications.
Preventing Purple Blood
There are some measures you can take to reduce the risk of developing purple blood:
- Avoid exposure to sulfur drugs, nitrates, and toxins known to cause methemoglobinemia.
- Treat infections quickly to prevent bacteria from altering blood.
- Maintain good heart health through diet, exercise, and medication adherence.
- Use protective gear to avoid skin exposure to industrial dyes.
- Drink water to flush out food dyes and limit intake of highly colored foods.
- Careful monitoring if you have anemia, heart defects, or enzyme deficiencies.
Conclusion
While purple blood is quite rare, being aware of the potential causes can help you seek prompt treatment if it occurs. Sulfhemoglobinemia is the most common reason, but dyes, infections, and congenital defects may also be to blame. Doctors can run tests to determine the source and offer appropriate solutions like oxygen, transfusions, antibiotics, or surgery. In most cases, the color change is reversible. But when paired with serious symptoms, seek immediate medical care for purple blood to prevent complications.