Fibromyalgia is a chronic condition that causes widespread pain, fatigue, and other symptoms, significantly affecting quality of life. Unfortunately, there are few effective treatments available. Recently, medical cannabis has gained attention as a potential treatment, leading many countries to approve its use for fibromyalgia. However, its success is limited-only about 25% of patients experience meaningful pain relief, and side effects like dizziness or fatigue are common. Not everyone responds to medical cannabis the same way, and researchers think this variability may partly be explained by differences in the gut microbiome-the community of bacteria and other microorganisms living in our digestive system. These microbes are known to influence various aspects of health, including pain and how the body processes medications. Our research focuses on understanding the link between the gut microbiome and fibromyalgia. We propose a study where 150 fibromyalgia patients will be treated with either cannabis oil or a placebo in a double-blind trial. By analyzing their symptoms and gut microbiome, we hope to identify patterns that could predict who will benefit most from cannabis treatment. If successful, this research could lead to more personalized and effective treatment options for fibromyalgia.