The pain relieving effects of acupuncture are so small, they lack clinical relevance, the results of a new study indicate.

Danish researchers analysed evidence from 13 acupuncture trials involving over 3,000 patients. The trials compared three types of treatment – real acupuncture, placebo or ‘pretend’ acupuncture and no acupuncture. These were analysed in relation to a range of common conditions, such as migraine, lower back pain and knee osteoarthritis.

The study found a small analgesic (pain relieving) effect with real acupuncture compared to placebo acupuncture. This corresponded to a reduction in pain levels of about 4mm on a 10mm pain scoring scale.

However a 10mm reduction on this scale is classed as ‘minimal’ or ‘little change’, therefore the apparent analgesic effect of acupuncture seems to be below a clinically relevant pain improvement, the team from the Nordic Cochrane Centre in Copenhagen said.

They also found a moderate difference between placebo acupuncture and no acupuncture (10mm on a 100mm pain scoring scale), but the effect of placebo acupuncture varied considerably. Some large trials reported effects of placebo that were of clear clinical relevance (24mm), while other large trials produced effects that seemed clinically irrelevant (5mm).

The team could not explain this variation.

“Our findings correspond with several Cochrane reviews on acupuncture for various types of pain, which all concluded that there was no clear evidence of an analgesic effect of acupuncture.

“Our findings also question both the traditional foundation of acupuncture and the prevailing theory that acupuncture has an important effect on pain,” the researchers said.

Details of these findings are published in the British Medical Journal.