Functional constipation is defined as constipation with- out an organic aetiology and is diagnosed according to the Rome criteria 1–3 . The symptom-based Rome criteria were first developed for adults in 1989 during a consensus meeting of experts in the field of functional gastrointes- tinal disorders. These criteria have been updated several times and are now internationally acknowledged and used for both research and clinical purposes. The first criteria for paediatric functional gastrointestinal disorders — the Rome II criteria — were published 10 years later, in 1999. The revised Rome IV criteria— for childhood and adult functional constipation — were published in 2016 (REFS 1–3 ) (BOX 1). Functional constipation, a common disorder in all age groups, shows some similarities in children and adults, but important differences exist regarding epidemiology, symptomatology, pathophysiology, diagnostic workup and therapeutic management. In this Review, we pro- vide an overview of the literature on childhood and adult functional constipation and discuss current and future diagnostic and therapeutic management strategies. Clinical symptoms Symptoms of functional constipation in both children and adults include hard, infrequent bowel movements, often accompanied by symptoms of bloating and abdominal pain. Children often present with symptoms of faecal incontinence, defined as the involuntary loss of stools in the underwear after being toilet trained, which is caused by overflow of soft stools passing around a solid faecal mass in the rectum (faecal impac- tion) 4 . Children with functional constipation also often have urinary symptoms, such as urinary incontinence and urinary tract infections 5 . Symptoms of faecal incon- tinence in adults are usually the result of another under- lying pathology, such as dysfunction of the pelvic floor or obstetric trauma 6,7 . Consequently, faecal incontinence is not included in the adult Rome IV criteria for functional constipation. It is important to note, however, that many adults might feel uncomfortable mentioning symptoms of incontinence and might not volunteer this informa- tion; the treating physician should, therefore, always ask about the presence of faecal incontinence. Adults often present with the sensation of incomplete evacuation or obstruction, often requiring manual manoeuvres to defaecate 3 . This symptom is rarely seen in children. Subtypes of functional constipation Three different subtypes of functional constipation are recognized: constipation with a normal transit, slow- transit constipation and rectal evacuation disorders. Faeces are propelled through the colon under the influ- ence of muscular contractions of the intestinal wall. Management of functional constipation in children and adults Mana H. Vriesman 1 *, Ilan J. N. Koppen 1 , Michael Camilleri 2 , Carlo Di Lorenzo 3 and Marc A. Benninga 1 Abstract | Functional constipation is common in children and adults worldwide. Functional constipation shows similarities in children and adults, but important differences also exist regarding epidemiology, symptomatology, pathophysiology, diagnostic workup and therapeutic management. In children, the approach focuses on the behavioural nature of the disorder and the initial therapeutic steps involve toilet training and laxatives. In adults, management focuses on excluding an underlying cause and differentiating between different subtypes of functional constipation — normal transit, slow transit or an evacuation disorder — which has important therapeutic consequences. Treatment of adult functional constipation involves lifestyle interventions, pelvic floor interventions (in the presence of a rectal evacuation disorder) and pharmacological therapy. When conventional treatments fail, children and adults are considered to have intractable functional constipation, a troublesome and distressing condition. Intractable constipation is managed with a stepwise approach and in rare cases requires surgical interventions such as antegrade continence enemas in children or colectomy procedures for adults. New drugs, including prokinetic and prosecretory agents, and surgical strategies, such as sacral nerve stimulation, have the potential to improve the management of children and adults with intractable functional constipation. 1 Department of Pediatric Gastroenterology and Nutrition, Emma Children’s Hospital, Amsterdam UMC, University of Amsterdam, Amsterdam, Netherlands. 2 C.E.N.T.E.R. Program, Division of Gastroenterology and Hepatology, Mayo Clinic, Rochester, MN, USA. 3 Division of Gastroenterology, Hepatology and Nutrition, Nationwide Children’s Hospital, Columbus, OH, USA. *e-mail: m.h.vriesman@ amc.nl https://doi.org/10.1038/ s41575-019-0222-y REVIEWS NATURE REVIEWS | GASTROENTEROLOGY & HEPATOLOGY