Acupuncture prevents headaches and migraines but faked treatments when needles are incorrectly inserted appear to work nearly as well, German researchers said on Wednesday.

Their findings suggest the benefits of acupuncture may stem more from people's belief in the technique, said Klaus Linde, a complementary medicine researcher at the Technical University in Munich, who led the analysis published in the Cochrane Review journal.

"Much of the clinical benefit of acupuncture might be due to non-specific needling effects and powerful placebo effects, meaning selection of specific needle points may be less important than many practitioners have traditionally argued," he said in a statement.

Acupressure and acupuncture both are based on the theory of lines of energy running through the body. With acupressure, a fingertip or a bead is used to press a specific pressure point, while needles are used in acupuncture.

Several studies have shown both treatments may stimulate the release of hormones known as endorphins, which can relieve stress, pain and nausea.

Linde and colleagues conducted two separate reviews that included 33 studies of nearly 7,000 men and women to see whether the technique was effective at preventing headaches and migraines.

Overall, they found that over eight weeks people treated with acupuncture suffered fewer headaches compared to men and women given only pain killers.

When it came to migraines, the needles beat drugs but faked treatments worked too, the researchers said. For less severe headaches, acupuncture worked just slightly better than sticking the needles randomly, the researchers said.

"Doctors need to know how long improvements associated with acupuncture will last and whether better trained acupuncturists really achieve better results than those with basic training only," Linde said.