Cupping refers to an ancient Chinese practice in which a cup is applied to the skin and the pressure in the cup is reduced (by using change in heat or by suctioning out air), so that the skin and superficial muscle layer is drawn into and held in the cup. In some cases, the cup may be moved while the suction of skin is active, causing a regional pulling of the skin and muscle (the technique is called gliding cupping).
This treatment has some relation to certain massage techniques, such as the rapid skin pinching along the back that is an important aspect of tuina (12). In that practice, the skin is pinched, sometimes at specific points (e.g., bladder meridian points), until a redness is generated. Cupping is applied by acupuncturists to certain acupuncture points, as well as to regions of the body that are affected by pain (where the pain is deeper than the tissues to be pulled). When the cups are moved along the surface of the skin, the treatment is somewhat like guasha (literally, sand scraping), a folk remedy of southeast Asia which is often carried out by scraping the skin with a coin or other object with the intention of breaking up stagnation. Movement of the cups is a gentler technique than guasha, as a lubricant allows the cup to slide without causing as much of the subcutaneous bruising that is an objective of guasha. Still, a certain amount of bruising is expected both from fixed position cupping (especially at the site of the cup rim) and with movement of the cups.
Traditional cupping, with use of heated cups, also has some similarity to moxibustion therapy. Heating of the cups was the method used to obtain suction: the hot air in the cups has a low density and, as the cups cool with the opening sealed by the skin, the pressure within the cups declines, sucking the skin into it. In this case, the cups are hot and have a stimulating effect something like that of burning moxa wool.
In some cases, a small amount of blood letting (luoci; vein pricking) is done first, using a pricking needle, and then the cup is applied over the site. The pricking is usually done with a three-edged needle, applied to a vein, and it typically draws 3–4 drops of blood (sometimes the skin on either side is squeezed to aid release of blood). A standard thick-gauge acupuncture needle or plum blossom needle may be used instead. This technique is said to promote blood circulation, remove stasis, and alleviate swelling and pain. It is employed especially when there is a toxic heat syndrome and for a variety of acute ailments.