Purpura and petechiae are spots of skin discoloration that occur when small blood vessels under the skin break and bleed. The main difference between the two is their appearance.
Below, we describe what purpura and petechiae are and the key differences between them. Next, we explore their causes and treatments, and when to contact a doctor.
Purpura and petechiae can both appear in rash-like clusters. An unexplained rash may require treatment, and any child with an unexplained rash and a fever should receive urgent medical attention.
Purpura form when tiny blood vessels called capillaries burst and leak, causing blood to pool beneath the skin. They are also known as blood spots or skin hemorrhages. Though they are usually flat, they can be slightly raised.
In most cases, purpura develop in rash-like clusters on a single area of skin, which may be large. Generally, the larger the affected area, the more severe the underlying bleeding.
A purpura cluster is not generally irritating or itchy. The spots are also non-blanching, meaning that they do not fade or change color under pressure.
As purpura heal and the body breaks down and absorbs the pooled blood, the patches change color. These changes vary — a spot may turn from reddish-purple to brown, orange, blue, or green.
Purpura do not represent a medical condition. They are a symptom.
Generally, petechiae are smaller versions of purpura, and they, too, are sometimes called blood spots. They form when capillaries break and leak blood that pools beneath the skin.
Like purpura, petechiae change color as the body breaks down and absorbs the pooled blood. The color transitions from reddish-purplish to brown, orange, blue, or green, and these spots do not fade or change color under pressure.
Petechiae can develop in small clusters or patches, resembling a rash. This may spread over a larger area of skin or be confined to a single area. Petechiae can occur around or among purpura.
Petechiae in children
Petechial rashes can develop in children. According to estimates,
Pediatric petechial rashes are often harmless and resolve on their own. However, it may be necessary for the doctor to treat the underlying cause.
Like purpura, petechiae are a symptom of a health issue. It is important to consult a doctor if a child develops any unexplained rash.
The most obvious difference involves size: petechiae are smaller than 2 mm, while purpura are larger. Purpura may be petechiae that have spread and joined together, forming larger areas of discoloration.
Both petechiae and purpura clusters tend to have rash-like appearances. Though the spots are often flat, they can be slightly raised.
There are three types of purpura and petechiae:
- Thrombocytopenic purpura and petechiae: These occur due to conditions that cause the irregular destruction of blood platelets — cell fragments that help the blood clot. Autoimmune conditions or certain medications or infections can have this effect.
- Non-thrombocytopenic purpura and petechiae: These occur when blood vessels are damaged or ruptured, or due to the loss of the skin’s structural elements.
- Purpura and petechiae from other clotting disorders: These disorders may relate to medication use, as in the case of warfarin-induced necrosis or heparin-induced thrombocytopenia.
A wide range of factors can cause purpura and petechiae to develop, such as:
- straining while coughing, vomiting, lifting something heavy, exercising vigorously, or using the bathroom
- damage from UV light
- skin aging, leading to a loss of collagen
- laser treatments
- vitamin K deficiency
- vitamin C deficiency, known as scurvy
- allergic reactions, such as those caused by insect bites
- medical procedures and surgeries
- skin damage or trauma
- blood vessel damage
Certain medications can cause purpura and petechiae, including:
- medications for overactive autoimmune disorders, such as lupus, arthritis, psoriasis, and eczema
- sulfonamides, a type of antibiotic
- blood-thinning medications
- heart medications
- chemotherapy medications
Other health conditions
Several autoimmune conditions or health issues that cause irregular bleeding or affect blood clotting can cause purpura and petechiae. Among them are:
- Sjogren’s syndrome
- Schamberg’s disease, which causes blood vessels in the skin to leak
- Finkelstein’s disease, which causes severe hemorrhaging and swelling
- Wiskott-Aldrich syndrome, which impairs blood clotting
- Bernard-Soulier syndrome, which also impairs clotting
- Glanzmann thrombasthenia, a bleeding disorder
- idiopathic thrombocytopenic purpura, a clotting disorder
Many other medical conditions that can cause blood vessels to burst or leak can also cause purpura and petechiae, including:
- chronic liver disease
- an embolism, or blockage in a blood vessel
- calciphylaxis, an irregular deposition of calcium on the blood vessel walls
- fibrointimal hyperplasia, an enlargement of tissue due to an increase in cell numbers
- Ehlers-Danlos syndromes, a group of inherited disorders that affect connective tissue
- inflammation of the small blood vessels
- Henoch-Schönlein purpura, which causes this inflammation
- cancerous tumors
Infections can also cause blood vessel damage and lead to purpura and petechiae. Some of these infections and pathogens include:
The key to treating purpura and petechiae is to address the underlying cause. This treatment may involve:
- vitamin K or C supplements or dietary changes
- anti-inflammatory medications
- medications to increase the platelet count
- organ transplant or spleen removal
- other surgical procedures
- chemotherapy or radiation therapy
Purpura or petechiae resulting from minor injury often do not require medical attention, as they usually heal on their own. If there is pain or swelling, the following may help:
- taking over-the-counter pain medication, such as acetaminophen (Tylenol)
- applying an ice pack wrapped in cloth for 15–20 minutes at a time
- avoiding activities that strain or put pressure on the affected area
- staying hydrated and having a healthful, balanced diet
Unexplained rashes of any kind require medical attention,
People who develop purpura or petechiae along with additional symptoms should also contact a doctor.
Both types of discoloration have associations with underlying health conditions, many of which require medical treatment. Receiving a prompt diagnosis and treatment reduces the risk of serious complications.
Purpura and petechiae are discolored spots on the skin that appear in rash-like clusters. Both result from blood vessels breaking and leaking. Purpura are larger than petechiae. They may develop when numerous petechiae join together.
There are many possible causes of purpura and petechaie, from a minor injury or medication to an infection or genetic condition. Overall, it is important to contact a doctor about any unexplained rash.