Purpura occurs when small blood vessels burst, causing blood to pool just under the skin. They appear as small purple spots just beneath the skin's surface.

Purpura, also known as skin hemorrhages or blood spots, can signal a number of medical problems, ranging from minor injuries to life-threatening infections.

Purpura is a symptom rather than a disease in itself, and there are a number of potential causes.

In this article, we will explain what purpura is, why it happens, its diagnosis, and treatment.

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An example of a purpura rash.

Purpura is characterized by small purple spots on the skin, typically 4-10 millimeters in diameter. Some people develop larger patches of 1 centimeter or greater. These are called ecchymoses.

Sometimes the spots can appear on mucous membranes, for instance, inside the mouth.

Purpura tends to occur in clusters that are found in a single area or cover a large portion of the body. The larger the rash is, the greater the bleeding will often be.

Unlike some other rashes, purpura will not change color or blanch when pressed. The rash can look a lot like tiny clusters of bruises, but the skin should not be itchy or irritated - this would suggest a cause other than purpura.

Purpura itself is a symptom rather than a condition. To determine the cause, doctors must run a range of tests. These tests will assess the patient's nutrition, platelet levels, inflammation, potential for infection, and blood vessel health.

Treatment for purpura usually requires treating the rash's underlying cause.

Doctors break purpura rashes into two categories based on platelet counts. Platelets are cell fragments that help blood clot more effectively, preventing dangerous bleeding.

  • Thrombocytopenic purpuras - platelet counts are low, suggesting an underlying clotting disorder.
  • Nonthrombocytopenic purpuras - platelet levels are normal, suggesting another cause.

A low platelet count can cause excessive bleeding and bruising and be caused by a number of factors, including:

A range of underlying medical conditions can cause both kinds of purpura.

One of the most-studied varieties of purpura is Henoch-Schönlein purpura, a nonthrombocytopenic version of purpura. More common among young children, this type of purpura is frequently preceded by a respiratory infection. Symptoms often go away on their own, but some people with Henoch-Schönlein purpura suffer dangerous inflammation that leads to kidney problems.

Idiopathic thrombocytopenic purpura (ITP) is a form of purpura with an unknown cause. Patients with ITP experience platelet destruction in the bloodstream. This leaves them more at risk of the bleeding that creates purpura's typical rash.

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A lack of vitamin C can lead to purpura.

To treat purpura, doctors must determine its cause. Purpura that does not lower platelet levels (nonthrombocytopenia) has a range of causes and risk factors, including:

  • Disorders and infections present from birth that cause abnormalities in blood vessels or blood production, such as Ehlers-Danlos syndrome and rubella.
  • Amyloidosis, which causes amyloid plaques to build up in the body.
  • Blood vessel deterioration associated with age.
  • A lack of vitamin C, also known as scurvy.
  • Infectious or inflammatory diseases that affect the blood vessels.
  • Some drugs, such as steroids and sulfonamides.

Purpura with a lowered platelet count (thrombocytopenia) has a number of potential causes:

  • drugs that reduce platelet count
  • recent blood transfusions
  • Rocky Mountain spotted fever
  • systemic lupus erythema
  • severe infections, including HIV and hepatitis C

ITP occurs when the body attacks its own platelets, increasing the risk of bleeding and purpuric rashes. In newborns whose mothers have ITP, reduced platelet count can also lead to purpura.

Diseases that impair bone marrow function may restrict the body's ability to make platelets, and attack bone marrow, such as:

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An example of a purpura rash.
Image credit: Hektor

The main symptom of purpura is a purplish-red rash just beneath the skin's surface. The rash can appear anywhere on the body, including on mucous membranes such as the lining of the mouth.

The symptoms that sometimes accompany purpura can help identify its cause.

Patients who experience purpura with any of the following symptoms should seek medical treatment:

  • Low platelet count, which may lead to increased bleeding after an injury, bleeding gums or nose, or blood in urine or bowel movements.
  • Sore, swollen joints, particularly in the ankles and knees.
  • Gut problems such as nausea, vomiting, diarrhea, or stomach pain.
  • Kidney problems, particularly protein or blood in the urine.
  • Excessive tiredness.

Because purpura can signal an underlying medical problem, it may lead to complications if left untreated. When purpura is the result of a blood clotting condition, the untreated disorder can cause life-threatening bleeding. Quick diagnosis and treatment of the underlying cause can reduce a patient's risk of serious complications.

Kidney damage can occur in people with Henoch-Schönlein purpura; this damage may require dialysis or a kidney transplant and can become life-threatening if left untreated.

Henoch-Schönlein purpura may also cause a rare condition in which the bowel folds over itself; this creates a bowel obstruction that restricts digestion. Bowel obstructions can be fatal if left untreated.

ITP occasionally causes bleeding in the brain causing permanent brain damage or death if not promptly treated.

Purpura itself is not a disease but a symptom of another problem. The only effective method for preventing purpura is avoiding the conditions that cause it. As most of these conditions are not due to lifestyle factors, there is little a person can do to reduce the risk of purpura.

Risk factors for purpura include:

  • blood clotting issues caused by medication or disease
  • infectious diseases, particularly among children and the elderly
  • poor nutrition when it leads to a lack of vitamin C
  • some forms of cancer, such as leukemia and myeloma
  • inflammatory conditions and disorders, such as Ehlers-Danlos syndrome
  • advanced age
  • poor blood vessel health

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A skin doctor should be able to diagnose purpura with a physical examination.
Image credit: Dr. James Heilman

The purple spots of purpura are fairly easy to tell apart from other rashes. Purpura is not normally accompanied by itching or other common skin issues. However, finding the underlying cause of purpura can be tricky.

Doctors often ask questions such as:

  • Do you have any other symptoms?
  • Does anyone else in the home have the same symptoms?
  • How long have you had the rash for?
  • Have you had this rash before?
  • Do you take any medications?
  • Are there any other medical problems?

A number of routine tests, beginning with a complete blood count (CBC) blood test, help investigate the cause of purpura. A CBC will reveal whether the patient has low platelets and whether any underlying infections are occurring.

If the doctor suspects ITP, they may order bone marrow testing. A skin biopsy can also provide important information, particularly when a doctor is unable to find an underlying cause for the purpura.

Some forms of skin cancer look similar to the purple spots of purpura. A biopsy can rule out skin cancer.

If a doctor suspects Henoch-Schönlein purpura, urine tests can assess kidney function by testing for protein and blood in the urine.

Doctors may also perform other tests based on the patient's symptoms and the suspected diagnosis.

Not all cases of purpura demand immediate treatment. Doctors often opt to watch the patient for other symptoms to see if they go away on their own. Children experiencing Henoch-Schönlein purpura are often likely to get better without treatment.

When treatment is necessary, it is not due to the rash itself. Treatment is needed for causes such as leukemia, or effects including kidney failure.

Treatment for Henoch-Schönlein purpura

Treatment for Henoch-Schönlein purpura focuses on improving the symptoms. Doctors may recommend non-steroidal anti-inflammatory drugs (NSAIDS) to reduce inflammation and pain. Steroid treatment can reduce kidney damage and abdominal pain. If kidney damage is severe, doctors may prescribe drugs to suppress the immune system.

Treatment for ITP

ITP symptoms range from mild to severe, and some patients require no treatment at all. Those who do may benefit from drugs designed to boost platelet count, or removal of the spleen.

The spleen can destroy or hold on to platelets, so, by removing it, platelet count is allowed to rise.

Lifestyle treatments can also help since drugs such as aspirin prevent platelets from aggregating and clotting.

Drugs that suppress the immune system such as prednisone may help elevate platelet levels. In patients who suffer platelet counts that are low enough to be life threatening, doctors may offer immune globulin treatment.

Treatment for other forms of purpura

Treatment for other forms of purpura centers around tackling the underlying cause. This can include options such as chemotherapy, antiviral drugs, steroid medications, antibiotics, and surgery.

Corticosteroids - these can help increase platelet count by reducing the activity of the immune system. The drug will be used for 2-6 weeks to ensure the platelets return to a safe level.

The side effects of using corticosteroids for an extended period of time include cataracts, bone loss, and weight gain.

Intravenous immunoglobulin - if the purpura causes significant bleeding, intravenous immunoglobulin can help increase platelet levels. This treatment is normally only effective in the short term.

Side effects include nausea, fever, and headache.

Romiplostim (Nplate) and eltrombopag (Promacta) - these are the latest medications to be used in the treatment of ITP. They both encourage the bone marrow to produce more platelets.

Side effects include dizziness, headaches, joint and muscle pain, nausea, vomiting, increased blood clot risk, and acute respiratory distress syndrome.

Rituximab (Rituxan) - helps lower the immune response. Predominantly used to treat thrombocyotopenic purpura and patients who do not respond to corticosteroids. Side effects include sore throat, low blood pressure, fever, and rash.

When purpura is caused by a medical condition that cannot be cured, ongoing checking of platelet levels and organ functioning may be necessary.