Cupping therapy falls under the classification of 'alternative medicine', altough widely practiced today it has been around for a very long time. There is evidence of cupping therapy being used by the egyptians in 1500 B.C.E. and in recent years becoming popular again. The basic idea of cupping therapy is to use cups applied to the skin to create suction. Cupping therapy is used for the same reasons people get deep tissue massage, because it is supposed to increase blood flow, ease tension, increase blood flow, and reduce stress allowing the body to heal quickly. The cups used for cupping therapy can be made of glass, bamboo, or silicone. Fire is used to burn a flammable liquid within the cup(such as alcohol), and then the cup is flipped upside down on the patient's skin, as the cup cools it creates a vacuum.
The modern version of cupping doesn't use fire, and simply uses a machine to vacuum out all of the air within the cup. Cups are left on the skin with suction for around 3 minutes, expanding the blood vessels. After the cup is removed the therapists uses a small scalpel to make tiny cuts on the skin where the cups were left on the skin, and then a second round of suction in the same place is applied removing a very small amount of blood from the area. It is common for first timers to only receive one cup to 'see how it feels', people who get cupping therapy done often usually don't have more than 7 cups done in a session. After the session it is common to receive an antibiotic ointment over the area to prevent infection and your skin usually goes back to normal within 10 days. Some people combine acupuncture with cupping therapy, this is called needle cupping when an acupuncture needle is applied before the cups are applied with suction.
Cupping therapy is said to help with many ailments such as fertility, acne, anemia, hemophilia, arthritis, fibromyalgia, high blood pressure, migraines, anxiety, depression, allergies, asthma, and varicose veins.
Cupping is considered safe as long as you go to a certified profesional, but you could always get some mild side effects such as burns, bruises, and skin infections. You should always consult with a doctor before trying any form of new procedure even if it is considered an alternative medicine like cupping therapy.