Gua Sha is used as a way of moving stagnant blood and fluid in the tissues. These fluids get stuck from old bruises, other injuries, injections, and general muscle tightness and trigger points. It’s like your closets at home; over time they just accrue stuff and need to be expunged.
Gua Sha is performed with a tool (I typically use a Chinese soup spoon or sea shell, depending on the area) and some lubricant to be applied to a specific area. Other commercial tools are typically made of bull’s horn and jade. Western medicine has developed its own similar treatment called Graston. Gua Sha differs from cupping in that small rounded areas are more easily treated with the latter.
With Gua Sha, fluids are brought to the surface. Some bruising can occur but it is not new bruising, only the expulsion of old fluids. The bruising typically goes away within a week. The aftereffect is a looser muscle, more range of motion and improved circulation of blood.