Purpura
Definition
Purpura is purple-colored spots and patches that occur on the skin, and in mucus membranes, including the lining of the mouth.
Alternative Names
Blood spots; Skin hemorrhages
Considerations
Purpura occurs when small blood vessels leak blood under the skin.
Purpura measure between 4 and 10 millimeters (mm) in diameter. When purpura spots are less than 4 mm in diameter, they are called petechiae. Purpura spots larger than 1 centimeter(cm) are called ecchymoses.
Platelets help the blood clot. A person with purpura may have a normal platelet count (non-thrombocytopenic purpuras) or a low platelet count (thrombocytopenic purpuras).
Causes
Non-thrombocytopenic purpuras may be due to:
- Amyloidosis (disorder in which abnormal proteins build up in tissues and organs)
- Blood clotting disorders
- Certain infections
- Congenital cytomegalovirus (condition in which an infant is infected with a virus called cytomegalovirus before birth)
- Congenital rubella syndrome
- Fragile blood vessels seen in older people (senile purpura)
- Hemangioma (abnormal buildup of blood vessels in the skin or internal organs)
- Inflammation of the blood vessels (vasculitis), such as Henoch-Schönlein purpura, which causes a raised type of purpura
- Injury
- Medicines that affect platelet function or clotting factors
- Pressure changes that occur during vaginal childbirth
- Scurvy (vitamin C deficiency)
- Steroid use
Thrombocytopenic purpura may be due to:
- Idiopathic thrombocytopenic purpura (ITP) -- a bleeding disorder
- Immune neonatal thrombocytopenia (can occur in infants whose mothers have ITP)
- Medicines that reduce the platelet count
- Meningococcemia (bloodstream infection)
When to Contact a Medical Professional
Contact your health care provider for an appointment if you have signs of purpura.
What to Expect at Your Office Visit
Your provider will examine your skin and ask about your medical history and symptoms, including:
- Is this the first time you have had such spots?
- When did they develop?
- What color are they?
- Do they look like bruises?
- What medicines do you take?
- What other medical problems have you had?
- Does anyone in your family have similar spots?
- What other symptoms do you have?
A skin biopsy may be done. Blood and urine tests may be ordered to determine the cause of the purpura.
References
James WD. Cutaneous vascular diseases. In: James WD, ed. Andrews' Diseases of the Skin: Clinical Dermatology. 14th ed. Philadelphia, PA: Elsevier; 2026:chap 30.
Piette WW. Purpura: Mechanisms and differential diagnosis. In: Bolognia JL, Schaffer JV, Cerroni L, eds. Dermatology. 5th ed. Philadelphia, PA: Elsevier; 2025:chap 22.
Reviewed By: Ramin Fathi, MD, FAAD, Director, Phoenix Surgical Dermatology Group, Phoenix, AZ. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.
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