Red dots on your skin can come from a wide range of causes, from completely harmless overgrowths of tiny blood vessels to signs of a bleeding disorder that needs medical attention. The key to figuring out what yours are lies in their size, texture, and whether they fade when you press on them.
The Glass Test: A Quick Way to Sort Them Out
Before anything else, try this simple check. Press the side of a clear drinking glass firmly against the red dots and watch what happens. If the dots fade or disappear under pressure, they’re “blanching,” which means blood is still flowing normally through the vessels beneath your skin. This points toward common, usually harmless causes like heat rash, minor irritation, or dilated blood vessels.
If the dots stay red, purple, or brown even under the glass, they’re “non-blanching.” That means blood has leaked out of the vessels and is sitting in the surrounding tissue. Non-blanching spots deserve closer attention because they can signal low platelets, a clotting problem, or in rare cases, a serious infection like meningitis. If non-blanching spots appear alongside fever, confusion, trouble breathing, or rapid spreading, get medical help immediately.
Cherry Angiomas: The Most Common Harmless Cause
If your red dots are small, raised bumps that have been there for a while and aren’t multiplying fast, they’re very likely cherry angiomas. These are caused by an overgrowth of tiny blood vessels in the skin, and they’re incredibly common. About 50% of adults develop them after age 30, and roughly 75% of adults over 75 have them. They range from pinpoint-sized to a few millimeters across, are bright red or dark red, and may bleed if scratched or nicked. They’re harmless and don’t need treatment unless they bother you cosmetically or get caught on clothing.
Petechiae: Tiny Flat Dots That Don’t Fade
Petechiae are flat, pinpoint dots smaller than 2 millimeters, roughly the size of a ballpoint pen tip. On lighter skin they look red, purple, or brown. On darker skin tones they tend to appear brown and can be harder to spot. They’re not raised, not rough, and not painful. The defining feature: they don’t fade when you press on them.
These dots appear when tiny capillaries under the skin break and leak a small amount of blood into the surrounding tissue. Sometimes the cause is purely mechanical. Hard coughing, vomiting, straining during a bowel movement, or even vigorous crying can create enough pressure to burst small capillaries, especially around the face, chest, and neck. In these cases, the spots usually resolve on their own within a few days.
Petechiae also show up when your platelet count is low. Platelets are the blood cells responsible for sealing off damaged vessels, and a normal count ranges from 150,000 to 450,000 per microliter of blood. When that number drops below normal, even minor bumps or friction can cause bleeding under the skin that doesn’t get plugged. Low platelets can result from viral infections, certain medications, autoimmune conditions like lupus, heavy alcohol use, or bone marrow problems including leukemia and lymphoma. Pregnancy can cause a mild drop in platelets close to delivery as well.
Purpura: Larger Patches of Leaked Blood
When non-blanching spots measure between 4 and 10 millimeters, they’re classified as purpura. Anything larger than 10 millimeters is essentially a bruise (called ecchymosis in medical terms). Purpura often appear in clusters and may come with visible bruising or skin discoloration around them. Like petechiae, they result from blood leaking out of vessels, but the larger size suggests more significant bleeding. Purpura can point to a blood disorder, a vitamin C deficiency, or certain medications that affect clotting.
Heat Rash
If your red dots appeared after sweating, exercise, or hot weather, heat rash is a strong possibility. It produces small, red, slightly rough bumps in areas where sweat gets trapped: skin folds, the chest, the back, and anywhere clothing creates friction. The itching is usually mild compared to other rashes. Heat rash resolves on its own once your skin cools down and dries out. Wearing loose, breathable fabrics and staying in cooler environments speeds recovery.
Folliculitis: Infected Hair Follicles
Red bumps centered around individual hair follicles, especially if they have a white or yellow tip, are likely folliculitis. The most common culprit is staph bacteria, which can enter follicles through shaving, tight clothing, or skin irritation. A yeast-based version causes itchy, uniform bumps that are often mistaken for acne, particularly on the chest and back. There’s also a form caused by pseudomonas bacteria picked up from poorly maintained hot tubs and heated pools, which typically appears one to three days after exposure.
Mild bacterial folliculitis often clears with warm compresses and good hygiene. Yeast-driven folliculitis won’t respond to antibacterial treatments and needs antifungal care instead, so getting the right diagnosis matters if bumps keep coming back despite standard treatment.
Keratosis Pilaris: Rough, Bumpy Patches
If you have clusters of small, rough, reddish bumps on your upper arms, thighs, buttocks, or cheeks that have been there for months or years, keratosis pilaris is the likely explanation. It happens when a protein called keratin clumps together inside hair follicles, forming tiny plugs. Dry skin and friction make it worse. The bumps are harmless and very common, though they can be cosmetically frustrating. Regular moisturizing and gentle exfoliation can reduce their appearance over time.
Contact Dermatitis and Eczema
Red dots or patches that are intensely itchy, flaky, or swollen may be an allergic or irritant reaction. Contact dermatitis shows up where your skin touched something it reacted to: a new soap, a metal in jewelry, a plant, or a chemical. Eczema produces dry, inflamed, sometimes thickened patches that can appear anywhere, including the hands, face, and inner elbows. Both conditions cause redness that blanches (fades with pressure), which distinguishes them from the bleeding-related causes above.
How to Tell What You’re Dealing With
- Raised and bright red, painless, stable over time: likely a cherry angioma.
- Flat, pinpoint, non-blanching, under 2 mm: petechiae. Consider whether you’ve strained recently or have other symptoms like unusual bruising or fatigue.
- Non-blanching, 4 to 10 mm, possibly with bruising: purpura, which warrants a medical evaluation.
- Small bumps in sweaty areas, mild itch: heat rash.
- Bumps around hair follicles with possible pus: folliculitis.
- Rough, sandpaper-like bumps on upper arms or thighs: keratosis pilaris.
- Itchy, flaky, inflamed patches that fade with pressure: eczema or contact dermatitis.
The glass test is your best starting point at home. Non-blanching dots that appear suddenly, spread quickly, or come with fever, confusion, or difficulty breathing need urgent medical evaluation. Non-blanching dots that appear gradually, without other symptoms, still deserve a doctor’s visit since blood work can check your platelet count and rule out underlying conditions. Blanching red dots, on the other hand, are far less likely to signal something serious, though persistent or worsening rashes are always worth getting checked.