What causes pinhead size blood spots under skin?

Pinhead-sized blood spots under the skin, known as petechiae, can be caused by various factors including minor trauma, certain medical conditions like thrombocytopenia (low platelet count), infections, or allergic reactions. They occur when small blood vessels break and leak blood into the skin. Certain medications and conditions that affect blood clotting can also contribute to their appearance. If petechiae occur without an obvious cause or are accompanied by other symptoms, it’s important to seek medical attention.