Although both forms of treatment involve poking the muscles, the actual treatment method, approach, and philosophy are very different. Acupuncture is an ancient form of Chinese medicine. Thin, tiny needles are placed in specific points along an invisible line called a meridian.
Meridians are pathways along which energy runs throughout the body. The belief is that the meridian pathways can be over-charged with energy, under-charged, or have areas of blockage. Placing needles at specific acupuncture points can help relieve energy deficits, areas of congestion, or blockage.
Once the needles are in place, the acupuncturist may gently twist or turn them to stimulate the point. The needles are left in place for a short period of time. This can vary from three to five minutes up to an hour. The average session is about 20 minutes.
The needles used in acupuncture may be dipped in herbs or natural pain relieving substances. But most often (at least in the U.S.), the needles are sterilized without the addition of any supplements. On the other hand, trigger point therapy also involves the use of needles. Areas of hyperirritability within the painful muscle (not necessarily along an acupuncture meridian) are injected with a numbing agent and antiinflammatory drug.
There is some evidence that just stimulating muscles with needles invokes some kind of healing response. Studies comparing patients who have had dry needling report similar results (reduced pain, improved function) when compared with trigger point injections.
More studies are needed to figure out what works and why it works. With the exception of some local skin irritation and the possibility of skin infection, both acupuncture and trigger point therapy seem to be safe, if not effective for chronic muscle pain.