There is low to moderate evidence that some herbal medicines may help lower back pain, a review by the Cochrane Back Group concludes. C. frutescens (Cayenne) reduces pain more than placebo and although H. procumbens, S. alba, S. officinale L., S. chilensis, and lavender essential oil also seem to reduce pain more than placebo, evidence for these substances was of moderate quality at best, the report said. The authors noted that eight authors of the included trials had a potential conflict of interest and four other authors did not disclose conflicts of interest.