Traditional acupuncture involves the insertion of extremely fine needles into the skin at specific "acupoints." This may relieve pain by releasing endorphins, the body's natural pain-killing chemicals, and by affecting the part of the brain that governs serotonin, a brain chemical involved with mood. One well-researched effect of acupuncture is reducing inflammation throughout the body. Acupuncture stimulates chemicals that reduce swelling and quiet unwanted immune responses and allergic reactions.