The breaking of blood vessels can be caused by trauma, various medical conditions or disease, states Reference.com. The most common cause of blood vessels breaking and bruising (discoloration due to bleeding into the skin) is trauma to the body.
Reference.com cites other medical conditions as causes, such as hypertension, vasculitis and varicose veins. The autoimmune disorder vasculitis causes inflammation in vessels, which can lead to breakage among small vessels, states Cleveland Clinic. This leaves small red or purple dots on the skin.
According to Healthline, several potential physical injuries, side effects or diseases can cause blood vessels to break. Its list of causes includes side effects from cancer treatments, such as radiation or chemotherapy, reactions to medications, allergic reactions and infections. Specific diseases and infections Healthline lists as associated with blood vessels breaking are meningitis, an inflammation of the membranes around the brain and spinal cord, leukemia, strep throat and sepsis where the whole body is inflamed due to a bacterial infection.
Healthline recommends seeking immediate medical attention if pain, bleeding through the skin, darkening of the skin or swelling accompanies the bleeding into the skin. Fortunately, most bleeding into the skin is due to light trauma and heals quickly, and if it doesn't, that is most likely due to high blood pressure.