There are little red spots on the body, how is it painless to return a responsibility

There are little red spots on the body, which can be considered as allergic purpura, mainly because contact with allergens induces immune reaction, leading to subcutaneous bleeding points, bleeding points will not fade under light pressure, generally about a week can subside by itself, if the little red spots grow on the trunk or limbs, rice grains or mung bean size, can be considered as cherry-like hemangioma.