Purpura are small spots caused by the leaking of blood from blood vessels near the surface of your skin. A purpuric rash is an area of your skin covered in purpura.

These spots may appear purplish red if you have light skin or brownish black if you have dark skin.

A purpuric rash is a symptom of an underlying medical condition but isn’t a medical diagnosis by itself. Many conditions ranging from mild to life threatening can cause purpura or a purpuric rash.

Read on to learn more about purpuric rashes, including symptoms, causes, and treatment options.

A purpuric rash is made up of spots that measure more than 2 millimeters (mm) — 0.08 inches (in.) — across. These spots are flat and can appear anywhere on your skin, including inside your mouth or on your mucous membranes. They usually appear reddish purple on lighter skin tones and brown or black on people with darker skin.

When you press on the rash, it won’t change color. Usually, your skin isn’t itchy or painful, but you may have some irritation.

Purpura types

Doctors use several other terms to refer to purpura that are small or large.

Petechiae are pinpoint spots of bleeding. They most often appear on your arms, stomach, or buttocks. They’re typically smaller than 2 mm across, but doctors sometimes classify spots as petechiae if they’re smaller than 4 mm.

Doctors refer to bleeding under your skin as ecchymosis if the discolored area is larger than 10 mm (0.4 in.). Ecchymosis is what most people call a bruise.

Here are some examples of how a purpuric rash can appear on your skin.

Purpura are classified as thrombocytopenic and nonthrombocytopenic purpura depending on whether you have a low platelet count.

Thrombotic thrombocytopenic purpura

Thrombotic thrombocytopenic purpura is a rare condition that occurs when you don’t have enough of the enzyme ADAMTS13, which leads to excessive blood clotting. “Thrombotic” refers to blood clots and “thrombocytopenic” refers to low levels of platelets.

About 3 to 11 cases develop per 1 million people per year, and it seems to affect women more than twice as often as men.

Approximately half of people have signs or symptoms of other medical conditions. These can include:

Thrombotic thrombocytopenic purpura can also develop in people:

Immune thrombocytopenic purpura

The other half of cases of thrombotic thrombocytopenia purpura develop when your immune system attacks platelet cells. When this happens, it’s called immune thrombocytopenic purpura, previously known as idiopathic thrombocytopenic purpura.

Factors that increase your risk of developing immune thrombocytopenic purpura include:

  • taking antibiotics or antivirals
  • viral or bacterial infections
  • rarely, some vaccines

Nonthrombocytopenic purpura

Nonthrombocytopenic purpura occurs when you have bleeding under your skin but normal platelet levels. It can be caused by factors like:

  • problems with your blood vessels
  • inflammation
  • some medications
  • viruses

Henoch-Schönlein purpura

One of the most common causes of nonthrombocytopenic purpura is a blood vessel condition called Henoch-Schönlein purpura. The exact cause of this condition isn’t known. According to the American College of Rheumatology, it often develops after an upper respiratory tract infection or cold.

It can also cause signs and symptoms like:

  • pain and swelling around joints
  • swelling under your skin
  • adnominal pain around your belly button
  • kidney disease

Solar purpura

Solar purpura is easy bruising that develops when your skin and blood vessels become more delicate due to long-term sun exposure. It becomes more common with age. It affects as many as 12% of people after age 50 and 30% of people after age 75.

Other causes of nonthrombocytopenic purpura

Other causes of nonthrombocytopenic purpura can include:

  • allergic vasculitis
  • side effects of some medications like steroids or sulfonamides
  • infectious and inflammatory diseases of your blood vessels
  • vitamin C deficiency
  • amyloidosis, the buildup of a protein called amyloid
  • other conditions that cause atypical activities with blood vessels

Purpura fulminans

Purpura fulminans is a medical emergency and has a high mortality rate. It is characterized by the rapid development of purpura and the death of skin tissue, which can accompanied by a high fever, chills, and muscle pain. If you develop symptoms of this condition, contact 911 or local emergency services.

It’s a rare condition caused by:

  • certain genetic protein deficiencies
  • infectious diseases like chickenpox or scarlet fever
  • acute illness, usually after sepsis, caused by a bacterial infection

Treatment for a purpuric rash usually revolves around targeting the underlying cause. Many rashes, such as those caused by Henoch-Schönlein purpura, often get better by themselves.

Without treatment, thrombotic thrombocytopenia can progress to multiple organ failure within days to weeks.

The first-line treatment for thrombotic thrombocytopenia often includes:

You may also receive:

There’s no specific treatment for nonthrombocytopenic purpura. Treatment for the underlying cause might include:

  • steroids
  • antibiotics
  • surgery
  • antiviral drugs
  • chemotherapy

Purpura can be a symptom of a serious condition. It’s important to see a doctor if you develop purpura for a proper diagnosis and treatment, especially if you have other concerning symptoms.

Here are some frequently asked questions people have about purpuric rashes.

What’s the difference between purpuric and petechial rashes?

Petechial rashes tend to be made up of smaller spots than purpuric rashes. Petechiae are less than 2 mm (0.08 in.) or 4 mm (0.16 in.) in size, depending on the definition being used.

What is the most common cause of purpura?

The main causes of purpura are conditions that cause problems with:

  • platelet levels
  • your blood’s ability to clot
  • the structure of your blood vessels

When should I worry about purpura?

It’s a good idea to visit a doctor any time you develop a purpuric rash, but it’s especially important to get medical attention if you have other symptoms like:

A purpuric rash is made up of small, discolored spots under your skin from leaking blood vessels. It can be caused by many different conditions that range from mild to life threatening.

It’s a good idea to visit a doctor any time you notice a purpuric rash so you can find out what’s causing it. Some underlying causes can lead to organ damage if left untreated.

Purpura fulminans sources

Please note that images appearing in the sources on purpura fulminans may be disturbing for some readers, as this condition can cause extensive tissue damage and may be life threatening.

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