And a minimal acupuncture course works almost as well as traditional Chinese therapy, say the researchers. In a randomised controlled trial - the gold standard of clinical trials - researchers in Germany divided 270 patients with a similar severity of tension headache into three groups. Over an eight week period one set were treated with traditional acupuncture, one with minimal acupuncture (needles inserted only superficially into the skin, at non-acupuncture points), and one group had neither treatment ('control' group).

Those receiving traditional acupuncture care saw their headache rates drop by almost half - suffering 7 days less headaches over the four weeks following the treatment. Those receiving minimal acupuncture had 6.6 less days of headaches. While the control group experienced 1.5 less days of headaches - a drop of just a tenth.

Improvements to headache rates continued for months after the acupuncture treatment, though they began to rise slightly as time went on.

Those in the 'no treatment' group were subsequently given acupuncture for eight weeks after the main study period. These patients also improved significantly after the treatment, though not to the same level as those given acupuncture initially.

Of the 195 patients in the acupuncture groups, 37 reported some side effects - the most common being dizziness, other headaches and bruising.

Such a small difference in results between traditional and minimal acupuncture treatments seems to indicate that the location of acupuncture points and other aspects of traditional Chinese acupuncture do not make a major difference for tension headache, say the authors.

Acupuncture treatments are sometimes associated with strong placebo effects, caution the authors. But these findings show that acupuncture produces just as good improvements for tension headache sufferers as treatments already accepted, they conclude.