placebo gels were rubbed onto the skin in the same way as active treatments, we found that active treatments were significantly better than placebo. Creating double blind conditions in trials of counter irritants can be problematic as rubefacients irritate the skin whereas inactive placebos do not. Some studies allowed for this by removing the principle ingredient from the treatment, leaving a placebo vehicle containing some other potentially irritant ingredients. Although the number needed to treat for combined outcomes of trials of this type was greater (worse) than for trials with inactive placebo, the difference was not statistically significant and there was insufficient evidence to draw conclusions.