In this Clinical practice guide, an analysis is made of the diagnosis and treatment of adult patients with constipation and abdominal discomfort, under the spectrum of irritable bowel syndrome and functional constipation. These have an important personal, health and social impact, affecting the quality of life of these patients. In irritable bowel syndrome with a predominance of constipation, this is the predominant change in bowel movements, with recurrent abdominal pain, bloating and frequent abdominal distension. Constipation is characterised by infrequent or difficulty in bowel movements, associated with excessive straining during bowel movement or sensation of incomplete evacuation. There is often no underling cause, with an intestinal functional disorder being considered. They have many clinical and pathophysiological similarities, with a similar response of the constipation to common drugs. The fundamental difference is the presence or absence of pain, but not in a way evaluable way; "all or nothing". The severity depends on the intensity of bowel symptoms and other factors, a combination of gastrointestinal and extra-intestinal symptoms, level of involvement, forms of perception, and behaviour. The Rome criteria diagnose functional bowel disorders. This guide is adapted to the Rome criteria iv (May 2016) and in this first part an analysis is made of the alarm criteria, diagnostic tests, and the criteria for referral between Primary Care and Digestive Disease specialists. In the second part, a review will be made of the therapeutic alternatives available (exercise, diet, drug therapies, neurostimulation of sacral roots, or surgery), making practical recommendations for each one of them. (C) 2016 Published by Elsevier Espana, S.L.U.