Cupping therapy involves heating the air inside a glass cup, which removes some of the air from the cup. The cup is then quickly placed on the skin. This creates a negative pressure so the cup will pull the skin part of the way into the cup. The cup may be left in place for several minutes and then removed. The theory behind cupping is that it raises the stuck qi to the surface and allows room for new qi and blood to flow into the areas which will then promote healing.