Through suction, the skin is drawn into the cup by creating a vacuum in the cup placed on the skin over the targeted area. The vacuum can be created either by the heating and subsequent cooling of the air in the cup, or via a mechanical pump. The cup is usually left in place for somewhere between five and fifteen minutes. It is believed by some to help treat pain, deep scar tissues in the muscles and connective tissue, muscle knots, and swelling.
The cups can be various shapes including balls or bells, and may range in size from 1 to 3 inches (25 to 76 mm) across the opening. Plastic and glass are the most common materials used today, replacing the horn, pottery, bronze and bamboo cups used in earlier times. The low air pressure required may be created by heating the cup or the air inside it with an open flame or a bath in hot scented oils, then placing it against the skin. As the air inside the cup cools, it contracts and draws the skin slightly inside. More recently, vacuum can be created with a mechanical suction pump acting through a valve located at the top of the cup. Rubber cups are also available that squeeze the air out and adapt to uneven or bony surfaces.
In practice, cups are normally used only on softer tissue that can form a good seal with the edge of the cup. They may be used singly or with many to cover a larger area. They may be used by themselves or placed over an acupuncture needle. Skin may be lubricated, allowing the cup to move across the skin slowly.
Depending on the specific treatment, skin marking is common after the cups are removed. This may be a simple red ring that disappears quickly, the discolouration left by the cups is normally from bruising especially if dragging the cups while suctioned from one place to another to break down muscle fiber. Usually treatments are not painful.
Fire cuppingFire cupping involves soaking a cotton ball in 99% alcohol. The cotton is then clamped by a pair of forceps and lit via match or lighter. The flaming cotton ball is then, in one fluid motion, placed into the cup, quickly removed, and the cup is placed on the skin. Fire heats the inside of the cup and a small amount of suction is created by the air cooling down again and contracting. Massage oil may be applied to create a better seal as well as allow the cups to glide over muscle groups (e.g. trapezius, erectors, latisimus dorsi, etc.) in an act called "moving cupping". Dark circles may appear where the cups were placed because of rupture of the capillaries just under the skin, but are not the same as a bruise caused by blunt-force trauma. There are documented cases of burns caused by fire cupping.
Today, wet cupping is a popular remedy practiced in many parts of the Muslim world .
Alternatively, mild suction is created using a cup and a pump (or heat suction) on the selected area and left for about three minutes. The cup is then removed and small superficial skin incisions are made using a cupping scalpel. A second suction is used to carefully draw out a small quantity of blood.
In Finland, wet cupping has been done at least since the 15th century, and it is done traditionally in saunas. The cupping cups were made of cattle horns with a valve mechanism in it to create an partial vacuum by sucking the air out. Cupping is still used in Finland as an alternative medicine.