In a method of clotting blood in which the blood exhibits a reduced tendency to clot and may be from a person undergoing an anticoagulant therapy or having type A or B hemophilia or von Willebrand disease, a therapeutically effective amount of a composition comprising clay as the active ingredient is administered to a wound from which the blood emanates. Upon contacting the blood, this clay, which may be kaolin, bentonite, or any type of layered clay, causes the blood to clot. In a method of arresting blood flowing from a wound, a therapeutically effective amount of a composition comprising clay as the active ingredient is administered to the bleeding wound. In this method, the blood has a reduced tendency to clot and may be from a person undergoing an anticoagulant therapy or having at least one of hemophilia A or B or von Willebrand disease.