The conclusions of many trials and numerous systematic reviews of acupuncture are largely inconsistent.[5][13] An overview of Cochrane reviews found that acupuncture is not effective for a wide range of conditions, and they suggest it may be effective for only chemotherapy-induced nausea/vomiting, postoperative nausea/vomiting, and idiopathic headache.[13] An overview of high-quality Cochrane reviews suggests that acupuncture may alleviate certain kinds of pain.[14] A systematic review of systematic reviews found little evidence of acupuncture's effectiveness in treating pain.[5] The evidence suggests that short-term treatment with acupuncture does not produce long-term benefits.[15] Some research results suggest acupuncture can alleviate pain, though the majority of research suggests that acupuncture's effects are mainly due to placebo.[7] A systematic review concluded that the analgesic effect of acupuncture seemed to lack clinical relevance and could not be clearly distinguished from bias.[16]