Cao Gio-

Also known as "coin rubbing" or "coining", is practiced throughout Southeast Asia (esp. Vietnam and Thailand) and by immigrants from such areas to the US and other countries.  Literally, "Cao Gio" means catch the wind.  In the Southeastern Asia belief, the "wind" is a "body force" or humor that is  imbalanced. An excess of "wind" in the body can be released by pulling the "wind" to the surface of the body, creating a pathway in which it can be released.  Cao Gio uses a coin to create abrasion lines of the skin, extending from the spine outwards along the path of the ribs.  The body is first treated with an oil (eucalyptus, peppermint, cinnamon, winter green, menthol, camphor) or ointment or balm (such as Tiger Balm), then the edge of a coin makes linear red abrasions of the skin over and over again .  The amount of "wind" is measured by the degree of redness appearing on the body after coining, that also measures the severity of the illness.  If the red marks are mild, then the underlying illness is mild.  If the marks are severely red, then there is much "excess wind" and the disease is major. The long red marks on the back (up to 20) fade after a few days.  Cao Gio is used to treat a variety of illnesses such as aches, pains, fevers, colds, cough, nausea, abdominal pain, chills and symptoms related to changes in the weather.  

     Levels of evidence: There is no alpha, beta, gamma, or delta evidence of effectiveness.  

Also see gua sha, a closely related technique used in China and Korea, except a sharpened object is used to create the dermabrasion rather than a coin.