Bleeding under the skin shows up as flat, discolored patches that don’t fade when you press on them. The appearance varies widely depending on the size of the bleed, from tiny red dots smaller than a pinhead to large, spreading purple patches the size of your palm. What they all share is that characteristic non-blanching quality: unlike a normal rash, pressing on the area won’t make the color disappear, because the blood is trapped beneath the surface rather than flowing through intact vessels.
Three Types, Sorted by Size
Doctors classify bleeding under the skin into three categories based on how large the discolored area is, and each one looks distinctly different.
Petechiae are the smallest, measuring less than 2 millimeters across. They look like tiny pinpoint dots, usually red or reddish-purple, scattered across the skin. You might mistake them for a rash at first glance, but they won’t fade under pressure. They often appear in clusters and can show up on mucous membranes inside the mouth as well as on the skin.
Purpura refers to spots larger than 2 millimeters but smaller than about 1 centimeter. These look like small, flat, reddish-purple blotches, noticeably bigger than petechiae but not yet what most people would call a bruise.
Ecchymosis is the medical term for what most people recognize as a bruise: a flat, discolored area larger than 1 centimeter. It appears as a bluish-purple patch on the skin’s surface. Unlike a hematoma, which pools enough blood to create a raised, swollen lump that’s painful to touch, ecchymosis stays flat. Hematomas look puffy and feel tender, while standard bruises are level with the surrounding skin.
The Glass Test
A simple way to check whether discoloration is bleeding under the skin or just a rash is the glass test. Press the side of a clear drinking glass firmly against the spot and look through it. If the color fades or disappears, blood is still flowing normally through the vessels and you’re likely looking at an ordinary rash. If the spots stay visible through the glass, blood has leaked out of the vessels and is sitting in the tissue beneath your skin.
This test is especially important for identifying a meningitis rash, which often starts as a few small, isolated spots that are red, purplish, or brown. In the early stages of the illness, the rash may actually blanch when pressed, but as the infection progresses, the spots become non-blanching and can grow into larger, bruise-like marks within hours.
How Bruise Colors Change Over Time
A typical bruise moves through a predictable color sequence as your body breaks down and reabsorbs the trapped blood. It starts as a pinkish-red mark, shifts to dark blue or purple, then fades through violet and green before turning dark yellow and eventually pale yellow. The whole process takes about two weeks from start to finish. If a bruise hasn’t noticeably improved after two weeks, or if it’s growing rather than fading, that’s worth paying attention to.
Common Causes of Skin Bleeding
The most familiar cause is simple trauma: you bump into something, blood vessels break, and a bruise forms. But several medications can make bleeding under the skin happen more easily or from less obvious injuries.
Blood thinners and antiplatelet drugs like aspirin, warfarin, and newer oral anticoagulants are well-known culprits. NSAIDs (ibuprofen, naproxen) also increase bleeding risk, especially when combined with corticosteroids or taken long-term. If you need pain relief while on blood thinners, acetaminophen is generally a safer choice.
Less obviously, common antidepressants can contribute. SSRIs and SNRIs interfere with how platelets use serotonin to form clots, which can lead to easier bruising. Some specific antidepressants carry higher risk than others because of how they interact with other medications.
What Causes Petechiae Specifically
Petechiae deserve their own mention because they look different from ordinary bruises and often signal something other than a simple bump. The four main causes are low platelet counts (thrombocytopenia), platelets that don’t function properly, clotting disorders, and weakened blood vessel walls. If you notice clusters of tiny pinpoint dots appearing without any injury, particularly if they’re spreading or accompanied by fever, that pattern is more concerning than a single bruise on your shin.
Vitamin Deficiencies and Skin Bleeding
Vitamin C plays a direct role in keeping blood vessels strong. When levels drop low enough to cause scurvy, one of the earliest skin signs is small subcutaneous bleeding spots, along with thickening of the skin. This happens because collagen production falls off, and collagen is what keeps blood vessel walls intact. The connective tissue becomes fragile, vessels break more easily, and wounds heal poorly. The good news is that these skin changes reverse once vitamin C intake is restored.
Age-Related Bruising
If you’re older and noticing purple patches on your forearms and hands that appear without any memorable injury, you’re likely seeing senile (or actinic) purpura. This is the most common form of bleeding under the skin in elderly adults. It shows up as flat purplish patches, most often on the lower arms and hands (affecting nearly all people with the condition), followed by the lower legs, feet, and thighs. Years of sun exposure thin the skin and weaken the connective tissue supporting blood vessels, so even minor contact can cause a bleed. These patches typically fade within three weeks but tend to recur in the same sun-exposed areas.
When the Appearance Signals Something Serious
Most bruises are harmless and heal on their own. But certain patterns are worth flagging. Petechiae spreading rapidly across your body, especially with fever, can indicate meningitis or a serious blood disorder. A rash that starts as a few spots and grows into large, bruise-like blotches over hours is a medical emergency.
Unexplained bruising that shows up frequently without clear injuries, particularly in unusual locations like the torso or back rather than the shins and forearms, can point to underlying clotting problems. Some bleeding disorders, including von Willebrand disease and certain platelet function issues, don’t always show up on standard blood work, so persistent unexplained bruising may require more specialized testing beyond a routine blood count.