Purpura
Purple-red spots from bleeding under the skin
Quick Facts
- Type: Bleeding into the skin
- Spot size: Petechiae under 2 mm, purpura larger
- Common causes: Low platelets, fragile vessels, clotting issues
- Seek urgent care: Fever with rash, widespread spots, bleeding
Overview
Purpura refers to purple, red, or brownish spots and patches that develop when blood leaks from small vessels into the skin or the mucous membranes. Unlike a rash caused by inflammation, these marks do not fade or blanch when you press on them, because the blood sits in the tissue rather than inside the vessels.
Very small pinpoint spots under about 2 millimeters are called petechiae, while larger flat patches are called purpura, and very large bruise-like areas are called ecchymoses. Purpura is not a disease in itself but a sign that something is affecting the platelets, the blood vessel walls, or the body's clotting system. Some causes are minor, while others are serious and need prompt evaluation.
Symptoms
The hallmark of purpura is discolored areas of skin that do not turn white when pressed:
- Flat red, purple, or brown spots and patches
- Pinpoint dots (petechiae) or larger blotches
- Spots that do not blanch under pressure
- Sometimes a slightly raised, tender rash if blood vessels are inflamed
Depending on the cause, there may be other signs such as easy bruising, bleeding gums, nosebleeds, blood in the urine or stool, joint pain, or fever. Widespread purpura with fever can signal a serious infection and is a medical emergency.
Causes
Purpura is grouped into two broad types based on the platelet count. The causes include:
- Low or abnormal platelets (thrombocytopenic purpura): Conditions such as immune thrombocytopenia, certain medications, infections, or bone marrow problems reduce the platelets needed for clotting.
- Normal platelets (non-thrombocytopenic purpura): Fragile or inflamed blood vessels, as in aging skin, vitamin C deficiency, or vasculitis such as Henoch-Schonlein purpura.
- Clotting problems: Inherited or acquired disorders, or blood-thinning medications.
- Infections: Severe bacterial infections such as meningococcal disease can cause rapidly spreading purpura.
Risk Factors
- Use of blood thinners, aspirin, or steroids
- Older age with thin, fragile skin
- Recent viral or bacterial infection
- Autoimmune conditions
- Liver disease or blood disorders
- Nutritional deficiencies, such as low vitamin C or K
Diagnosis
Because purpura has many possible causes, doctors take a careful history and run tests to find the source:
- Physical exam: Looking at the size, location, and pattern of the spots and checking for other bleeding.
- Complete blood count: To measure platelets and look for anemia or infection.
- Clotting tests: To assess how well the blood clots.
- Additional tests: Such as a urine test, blood smear, or, in some cases, a skin biopsy or bone marrow exam.
Treatment
Treatment depends entirely on the underlying cause rather than the spots themselves:
- Stopping a triggering drug: If a medication is responsible, the doctor may change or stop it.
- Treating low platelets: Immune thrombocytopenia may be treated with steroids, immune globulin, or other medicines.
- Treating infection or inflammation: Antibiotics for bacterial infection, or anti-inflammatory treatment for vasculitis.
- Supportive care: Mild, age-related purpura on the forearms often needs no treatment beyond protecting the skin.
Serious causes such as severe infection or very low platelets require urgent hospital treatment.
Prevention
- Take blood thinners exactly as prescribed and report unusual bruising
- Protect fragile skin from bumps and pressure
- Eat a balanced diet with adequate vitamin C and K
- Manage underlying conditions such as liver disease or autoimmune disorders
- Keep up with vaccines that prevent severe infections
When to See a Doctor
See a doctor for any new purpura that you cannot explain. Seek emergency care immediately if purpura is accompanied by:
- Fever, especially with a rapidly spreading rash and feeling very unwell
- A stiff neck, severe headache, or confusion
- Heavy bleeding from the nose, gums, urine, or stool
- Severe abdominal or joint pain
Fever with spreading purpura can be a sign of a life-threatening infection and requires emergency services without delay.
Frequently Asked Questions
What is the difference between purpura and a bruise?
Both are bleeding under the skin, but a typical bruise follows an injury and fades through color changes. Purpura often appears without obvious injury and can signal a problem with platelets, blood vessels, or clotting, so unexplained purpura should be checked.
Is purpura dangerous?
It depends on the cause. Age-related purpura on the forearms is usually harmless, but purpura with fever, widespread spreading, or heavy bleeding can indicate a serious infection or blood disorder and needs emergency care.
How can I tell purpura from a normal rash?
Press a clear glass against the spots. Most rashes briefly fade or turn white under pressure, while purpura does not because the blood is outside the vessels. Non-blanching spots with fever are an emergency.
Can medications cause purpura?
Yes. Blood thinners, aspirin, steroids, and some other drugs can thin the blood or weaken vessels and cause purpura. Never stop a prescribed medication on your own; report new bruising or spots to your doctor.
Does purpura go away on its own?
Mild purpura from a minor or self-limited cause may fade over days to weeks. Purpura caused by an ongoing condition will persist or recur until the underlying problem is treated, which is why evaluation matters.
References
- MedlinePlus, U.S. National Library of Medicine. Bleeding into the skin.
- Merck Manual Consumer Version. Bruising and Bleeding.
- National Heart, Lung, and Blood Institute (NHLBI). Immune Thrombocytopenia.
- Mayo Clinic. Thrombocytopenia (low platelet count).