Small red spots on the skin can be petechiae, which are caused by bleeding under the skin due to blood vessel injuries or life-threatening conditions, explains Mayo Clinic. The spots are usually less than one-eighth of an inch in diameter and can be red, brown or purple in appearance.
Petechiae do not disappear when the skin is pressed and can spread over large areas of the body in a matter of hours, according to eMedicineHealth. When they develop quickly, it can be a sign of a serious infection or a platelet abnormality, both of which require immediate treatment.
Common causes of bleeding under the skin and a subsequent development of petechiae include prolonged straining, the use of certain medications, and infectious diseases, suggests Mayo Clinic. Prolonged straining such as crying, coughing, vomiting, childbirth and weightlifting can cause tiny red dots to appear on the face, neck and chest. Medications that can cause petechiae include aspirin, atropine, carbamazepine, chloral hydrate, cimetidine, desipramine, indomethacin, morphine, naproxen, nitrofurantoin, penicillin and quinine.
Certain bacterial, viral and fungal infections can cause petechiae on the skin, in the mouth and on eyelids, explains Mayo Clinic. They include cytomegalovirus infections, parvovirus infections, endocarditis, hantavirus pulmonary syndrome, meningococcemia, mononucleosis, Rocky Mountain spotted fever, scarlet fever, strep throat and viral hemorrhagic fever. Other non-infectious causes include hemolytic uremic syndrome, idiopathic thrombocytopenia purpura, leukemia, infantile scurvy, vasculitis and vitamin K deficiency.