Petechiae are tiny, flat spots that appear when capillaries (the smallest blood vessels near the skin’s surface) break and leak blood into surrounding tissue. They can be a sign of something as minor as a hard coughing fit or as serious as a life-threatening blood infection. The key distinction is whether the spots are isolated and explainable or widespread and accompanied by other symptoms like fever, fatigue, or easy bruising.
These spots are usually less than 2 millimeters across, roughly the size of a pinpoint. They’re most often red, purple, or brown depending on skin tone, and they don’t fade when you press on them. That last detail is what separates petechiae from ordinary rashes. You can test this at home by pressing a clear glass against the spots. If the color disappears under pressure, it’s not petechiae. If the spots stay visible, the blood is trapped outside the vessels and can’t be pushed away.
Straining and Physical Causes
The most common and least worrisome cause of petechiae is simple physical strain. Forceful vomiting, a prolonged coughing episode, intense weightlifting, or even childbirth can generate enough pressure to rupture tiny capillaries. When this happens, the spots usually cluster in predictable areas: around the eyes, on the face, or on the upper chest. They’re limited to the area that experienced the most pressure.
These strain-related petechiae typically fade on their own within a few days and don’t come back unless you’re straining again. If you’ve recently had a stomach bug that caused heavy vomiting and you notice pinpoint spots around your eyes the next morning, that’s almost certainly the explanation. No treatment is needed.
Low Platelet Count
Platelets are the blood cells responsible for clotting. When your platelet count drops low enough, blood leaks from capillaries with little or no provocation. In immune thrombocytopenia (ITP), the immune system mistakenly destroys platelets faster than the body can replace them. When platelet counts fall below about 10,000 per microliter of blood (normal is 150,000 to 400,000), patients often develop petechiae and bruising from minimal contact.
Other conditions that lower platelet counts include leukemia and other blood cancers, aplastic anemia (where the bone marrow stops making enough blood cells), and certain viral infections like hepatitis C or HIV. If petechiae appear without an obvious physical cause and are widespread across your arms, legs, or torso, a low platelet count is one of the first things a blood test will check for.
Infections
Several infections can trigger petechiae, but the one doctors worry about most is meningococcal disease. This bacterial blood infection can cause a rash that progresses from a few vague spots to a widespread petechial eruption within hours. Petechiae develop in 50 to 80 percent of patients with meningococcal disease, typically starting on the trunk and legs before spreading. In severe cases, the small spots rapidly enlarge into larger purple patches as the infection overwhelms the body’s clotting system.
The critical warning signs that distinguish an infectious cause from a benign one are fever, rapid illness, confusion, stiff neck, and a rash that visibly worsens over a short period. Rocky Mountain spotted fever, endocarditis (infection of the heart valves), and severe sepsis from various bacteria can also present with petechiae. In children, the combination of a new petechial rash and fever always warrants urgent evaluation.
Medications That Cause Petechiae
Several drug classes can lead to petechiae through different mechanisms. Blood thinners reduce the blood’s ability to clot, making capillary leaks more visible. Some antibiotics (particularly penicillins and sulfonamides), seizure medications, and gout drugs like allopurinol can inflame small blood vessels in the skin, a condition called cutaneous small vessel vasculitis. This inflammation damages the vessel walls and allows blood to seep out, producing spots that range from pinpoint petechiae to larger purplish patches.
If you notice new petechiae after starting a medication, that timing is worth mentioning to your prescriber. Drug-related petechiae usually resolve after the medication is stopped or changed.
Vitamin C Deficiency
Vitamin C is essential for building collagen, the protein that gives structure to blood vessel walls. When vitamin C levels drop low enough to cause scurvy, capillaries weaken and bleed spontaneously. The petechiae in scurvy have a distinctive pattern: they cluster around hair follicles, often on the shins and thighs, and the hairs themselves may become coiled or corkscrew-shaped. This combination of perifollicular bleeding and abnormal hair growth is considered nearly diagnostic of scurvy.
Scurvy is rare in developed countries but still occurs in people with extremely limited diets, particularly older adults living alone, people with alcohol use disorder, and those with conditions that impair nutrient absorption.
Vasculitis and Autoimmune Conditions
IgA vasculitis (formerly called Henoch-Schönlein purpura) is an autoimmune condition where the immune system attacks small blood vessels. It’s most common in children and produces a characteristic set of four symptoms: palpable purpura (raised, non-blanching spots, often starting as petechiae), joint pain, abdominal pain, and kidney involvement. The rash typically appears on the legs and buttocks and feels slightly raised to the touch, unlike the flat petechiae from straining or low platelets.
Lupus, rheumatoid vasculitis, and other autoimmune diseases can also damage small blood vessels and cause petechiae. In these conditions, the spots are usually one piece of a larger picture that includes joint symptoms, fatigue, or organ involvement.
How to Tell Harmless From Serious
The context around petechiae matters more than the spots themselves. A few spots on your eyelids after vomiting are self-explanatory. Widespread petechiae that appear without a clear physical trigger are a different situation entirely. Here are the features that point toward a serious cause:
- Rapid spread: spots that multiply or enlarge over hours rather than days
- Fever: especially high fever with a sick appearance
- Easy bruising: bruises appearing from minor bumps or with no known cause
- Bleeding elsewhere: nosebleeds, bleeding gums, or blood in urine or stool
- Fatigue and pallor: suggesting an underlying blood disorder
- Joint or abdominal pain: which may point to vasculitis
Petechiae that are confined to one area, clearly linked to a strain event, and not accompanied by any other symptoms are rarely dangerous. Petechiae that are unexplained, widespread, or paired with any of the features above need a medical evaluation, often starting with a simple complete blood count to check platelet levels and rule out infection or blood disorders.