It has been found that celiac disease (CD) and non-celiac gluten sensitivity (NCGS) have a high prevalence in fibromyalgia (FM) patients. NCGS is a relatively new entity characterized by gastrointestinal and extra-intestinal manifestations in the absence of CD or wheat allergy. It is different from CD because anti-transglutaminase (anti-tTG) or endomysial antibodies (IgA-EmA) are lacking and the intestinal mucosa is normal or with mild abnormalities as increased intraepithelial lymphocytes in the absence of villous atrophy.