Cupping involves applying heated glass or plastic cups to specific areas of the skin in a way that creates suction to restore the flow of blood and energy, or qi, and stimulate healing. The cups are kept still or gently moved across the skin in a gliding fashion to loosen muscles, increase circulation and draw out toxins that linger in the tissues. It's a form of deep tissue therapy, explains Kathleen Greenough, a doctor of acupuncture and Chinese medicine at the Pacific College of Oriental Medicine in New York City. "By creating a vacuum inside the cup, using heat or suction, it draws the skin and layers of muscle into the cup, which allows [the technique] to break up muscle knots and bruising that's not visible. It also opens pores and circulation in the area and clears any obstructions like lactic acid and build-up of toxins from the environment."

In other words, with the suction effect, "we're creating a controlled injury that kick-starts the healing process," explains Dr. Charles Kim, an acupuncturist and assistant professor of rehabilitation medicine and anesthesiology at the NYU School of Medicine, Rusk Rehabilitation, who sometimes uses cupping for pain management in his practice. "It's a counter-irritant that creates more healing to the area we're addressing." During a session, the technique can cause mild discomfort, similar to having a massage on a sore area, but not pain.

[See: 11 Ways to Cope With Back Pain.]

In fact, cupping is particularly beneficial for relief from back pain, headaches, menstrual cramps and other painful conditions, experts say. In a 2011 study from China, after people with fibromyalgia had daily cupping sessions for 15 days, their pain symptoms and the number of tender points they had decreased considerably, effects that lasted for two additional weeks. More recently, a 2013 study from India found that when people with osteoarthritis of the knee had 11 cupping treatments over a 15-day period, they gained significant relief of pain, swelling and stiffness, results that were comparable to taking 650 milligrams of acetaminophen three times a day, according to the researchers.

The technique is also used to treat respiratory diseases (such as asthma, bronchitis and chronic cough), gastrointestinal conditions (like constipation) and high blood pressure, notes Kylie Study, a licensed acupuncturist and Traditional Chinese Medicine practitioner at the Beaumont Health System in Troy, Michigan. "It can be used as an adjunctive treatment [often with acupuncture or massage] or as a stand-alone treatment."

[See: 8 Lesser-Known Ways to Ruin Your Joints.]

After Jarone Ashkenazi fell and broke his left elbow playing basketball with friends during the summer of 2013, he ended up with a slipped disc and nerve compression in his neck. This led to numbness and tingling in his left arm and neck pain that endured long after the broken bone had healed. He went for physical therapy, which didn't help much, so then he went to a massage therapist for a while. When the massage therapist recommended he go for cupping treatments as well, Ashkenazi was initially skeptical about Eastern medicine but put that aside because he was so frustrated by his lack of progress.

During his first cupping session, "it felt amazing -- my whole back released; all the tension came out," recalls Ashkenazi, now 26, an assistant project manager at Equinox in Los Angeles. Over the next two months, he went for five more cupping sessions and the pain in his neck went away entirely. Now, he can exercise and move through everyday life more comfortably. "I'm definitely a firm believer in cupping," he says. "It really helped me."

It's an especially useful therapy if people can't tolerate anti-inflammatory drugs, Kim says. "Relief can be pretty quick -- I've had patients walk away from treatments feeling looser and more energized. Others need repeated treatments any time they have a flare-up of pain. There's tremendous variation in how people respond."