Researchers have demonstrated that fecal microbiome transplantation from fibromyalgia patients induces chronic pain symptoms in germ-free mice, establishing a causal role of gut microbes in fibromyalgia pathogenesis. This discovery, published in Neuron, highlights the gut-brain axis in chronic pain conditions and opens new avenues for microbiome-targeted therapies. The findings address longstanding uncertainties about the relationship between microbiome alterations and systemic pain syndromes in humans.