What Causes Petechiae?

Petechiae are tiny purple, red, or brown spots on the skin. They usually appear on your arms, legs, stomach, and buttocks. You might also find them inside your mouth or on your eyelids. These pinpoint spots can be signs of many different conditions — some minor, others serious. They can also appear as a reaction to some medications.

Though petechiae look like a rash, they’re actually caused by bleeding under the skin. One way to tell the difference is by pressing on the spots. Petechiae won’t turn white when you press on them. A rash will turn pale.

Causes of petechiae
Petechiae are caused when tiny blood vessels called capillaries break open. When these blood vessels break, blood leaks into your skin. Infections and reactions to medications are two common causes of petechiae.

Conditions that may cause petechiae include:Conditions that may cause petechiae include:
Possible cause Additional symptoms and informationCytomegalovirus (CMV) CMV is an illness caused by a virus. Other symptoms include fatigue, fever, sore throat, and muscle aches.Endocarditis This infection of the inner lining of the heart includes symptoms like fever, chills, fatigue, achy joints and muscles, shortness of breath, cough, and pale skin.Hantavirus pulmonary syndrome This viral infection causes flu-like symptoms and breathing problems. Other symptoms include fatigue, fever, and muscle aches.Injuries Damage to the skin, such as from blunt force (for example, a car accident), biting, or hitting can cause petechiae to form. A sunburn can also cause petechiae.Leukemia Leukemia is a cancer of your bone marrow. Other symptoms include fever, chills, fatigue, unintentional weight loss, swollen glands, bleeding, bruising, nosebleeds, and night sweats.Meningococcemia This is a bacterial infection in the respiratory tract. Other symptoms include fever, headache, muscle pain, and nausea.Mononucleosis (mono) Mono is a viral infection that’s transmitted through saliva and other bodily fluids. Other symptoms include extreme fatigue, sore throat, fever, swollen lymph nodes, swollen tonsils, and headache.Rocky Mountain spotted fever (RMSF) RMSF is a bacterial infection transmitted by ticks. Other symptoms include high fever, chills, severe headache, muscle aches, nausea, and vomiting.Scarlet fever This bacterial infection can develop in people after they’ve had strep throat. Other symptoms include a rash, red lines on the skin, flushing of the face, red tongue, fever, and sore throat.Scurvy Scurvy is caused by too little vitamin C in your diet. Other symptoms include fatigue, swollen gums, joint pain, shortness of breath, and bruising.Sepsis This is a life-threatening blood infection. Other symptoms include a high fever, fast heart rate, and trouble breathing.Straining Activities that cause you to strain can tear blood vessels in your face, neck, and chest. These activities include crying, coughing, vomiting, lifting weights, or giving birth.Strep throat Strep throat is a bacterial infection that causes a sore throat. Other symptoms include swollen tonsils, swollen glands, fever, headache, nausea, vomiting, and body aches.Thrombocytopenia Thrombocytopenia is a condition in which you have too few platelets — blood cells that help your blood clot. Other symptoms include bruises, bleeding from your gums or nose, blood in your urine or stool, fatigue, and yellow skin and eyes.Vasculitis Vasculitis is marked by swelling, narrowing, and scarring of the blood vessels. Other symptoms include fever, headache, fatigue, weight loss, aches and pains, night sweats, and nerve problems.Viral hemorrhagic fevers Infections such as dengue, Ebola, and yellow fever are all viral hemorrhagic fevers. These infections make it harder for your blood to clot. Other symptoms include high fever, fatigue, dizziness, aches, bleeding under the skin, and weakness.Petechiae are a side effect of certain drugs. Some examples of medications that may cause petechiae as a side effect include: Type of drugExamples Antibioticsnitrofurantoin (Macrobid), penicillin Antidepressantsdesipramine (Norpramin) Anti-seizure drugscarbamazepine (Carbatrol, Epitol, Tegretol, others) Blood thinnerswarfarin, heparin Heart rhythm drugsatropine (Atropen) Nonsteroidal anti-inflammatory drugs (NSAIDs)indomethacin (Indocin), naproxen (Aleve, Anaprox, Naprosyn) SedativesPetechiae are a side effect of certain drugs. Some examples of medications that may cause petechiae as a side effect include:
Type of drug ExamplesAntibiotics nitrofurantoin (Macrobid), penicillinAntidepressants desipramine (Norpramin)Anti-seizure drugs carbamazepine (Carbatrol, Epitol, Tegretol, others)Blood thinners warfarin, heparinHeart rhythm drugs atropine (Atropen)Nonsteroidal anti-inflammatory drugs (NSAIDs) indomethacin (Indocin), naproxen (Aleve, Anaprox, Naprosyn)Sedatives chloral hydrate

When to call your doctor
If you or your child has petechiae, call a doctor. Some of the underlying causes of petechiae are serious and need to be treated. It’s hard to know whether you have something mild or serious until you see your doctor for a diagnosis.

You should also call if you have serious symptoms like these:

high fever
trouble breathing
confusion
change in consciousness
COMPLICATIONS

Are there complications?
Petechiae themselves don’t cause complications, and they won’t leave scars. Some of the conditions that cause this symptom can have complications, such as:

damage to the kidneys, liver, spleen, heart, lungs, or other organs
heart problems
infections in other parts of your body

source: Healthline