The causes of purpura can vary depending on the type of purpura. Here are some common causes of purpura: Thrombocytopenic purpura: caused by a low platelet count in the blood, caused by infections, medication side effects, and certain cancers. Henoch-Schonlein purpura: caused by inflammation in the blood vessels, which can be triggered by infections, medications, or other factors. Senile purpura: caused by thinning and weakening of the skin and blood vessels, which can occur with age. Allergic purpura: This type of purpura is caused by an allergic reaction to medications, foods, or other substances. Trauma-induced purpura: This type of purpura is caused by physical trauma or injury to the skin and blood vessels. Infection-induced purpura: Certain infections, such as meningococcal meningitis or sepsis, can cause purpura. Note that purpura can also be a symptom of an underlying medical condition, such as leukemia, lupus, or vasculitis. If you experience purpura, it is important to seek medical attention to determine the underlying cause and receive appropriate treatment.