Purging disorder

Purging disorder is an eating disorder classified in DSM-5 as an other specified feeding or eating disorder, in which recurrent self-induced vomiting or misuse of laxatives, diuretics or enemas is used to influence body weight or shape in the absence of binge eating

It sits between bulimia nervosa and restrictive anorexia nervosa on the clinical spectrum, because purging behaviour and shape and weight overvaluation are present but the defining bulimic binge is absent and body weight is usually normal or only modestly reduced

The disorder is under-studied relative to anorexia and bulimia nervosa, and many estimates of prevalence, risk factors and treatment response are therefore drawn from community cohorts and from extrapolation rather than from dedicated clinical trials

Terminology and classification

• DSM-5 places purging disorder under other specified feeding or eating disorder, a residual category used when symptoms cause distress or impairment but do not meet full criteria for anorexia nervosa, bulimia nervosa or binge-eating disorder
• The essential behavioural criterion is recurrent purging at least once weekly for three months, using self-induced vomiting or the misuse of laxatives, diuretics or enemas, and the behaviour must not occur exclusively during episodes of binge eating
• The cognitive criterion is an undue influence of body shape and weight on self-evaluation, which distinguishes the disorder from vomiting caused by a medical illness or by a primary psychotic or factitious disorder
• ICD-10 assigns F50.8 to other eating disorders, and ICD-11 uses 6B82 for other specified feeding or eating disorder, so neither system provides a unique code for purging disorder and coding depends on the residual category
• It is distinguished from bulimia nervosa by the absence of objectively large binge episodes and from the binge-purge subtype of anorexia nervosa by the absence of significantly low body weight, although weight can fall into the low-normal range
• Some researchers argue that purging disorder should become a standalone diagnosis rather than remain an other specified category, because follow-up studies show persistent symptoms, medical complications and treatment-seeking independent of bulimia nervosa

History

• Purging without binge eating was described within the bulimia nervosa literature after Russell's 1979 account, but for two decades it was treated as a variant of bulimia rather than as a separate syndrome
• Keel and colleagues proposed formal research criteria for purging disorder in 2005 and published a series of community and clinical studies between 2005 and 2009 that distinguished it from bulimia nervosa on behavioural and outcome grounds
• The diagnosis entered DSM-5 in 2013 as an example under other specified feeding or eating disorder, which gave it a codable place in clinical practice without granting full diagnostic status
• Stice and colleagues reported in 2013 that 3.4% of a community cohort of 496 young women met criteria for purging disorder by age 20, a figure that became one of the most cited prevalence estimates for the disorder
• NICE guideline NG69, published in 2017, grouped purging disorder with other specified eating disorders for service planning and recommended evidence-based psychological treatment rather than a disorder-specific pathway
• The American Psychiatric Association practice guideline for eating disorders, updated in 2023, likewise treats purging disorder as part of the other specified group and recommends psychotherapy as first-line care with medication as an adjunct

Epidemiology

• Published lifetime prevalence estimates range from 1.1% to 5.3%, with the wide range reflecting differences in sampling frame, interview instrument and the threshold used for frequency of purging
• The Stice community cohort of 496 young women found a cumulative prevalence of 3.4% by age 20, which places purging disorder among the more common eating disorders in young adult populations
• Peak onset is in late adolescence and early adulthood, with most series reporting first symptoms between 18 and 20 years of age, although paediatric cases and midlife onset are recognised
• In one risk-factor study 77% of participants presenting with purging symptoms were female, consistent with the female preponderance seen across eating disorders, although male cases are probably under-recognised because purging is less often disclosed
• Population studies show that purging disorder is at least as common as bulimia nervosa in some community samples, whereas clinical samples contain far more bulimia nervosa because purging disorder is less often diagnosed
• The disorder is reported across high-income countries with the strongest data from North America, Europe and Australia, while data from low-income and middle-income settings are sparse because eating disorder services and surveillance are limited
• Mortality is low in absolute terms but clinically significant, and a review of 11 deaths among people with purging disorder attributed five to the disorder itself and six to suicide, highlighting the psychiatric severity of the group
• Children and adolescents with purging disorder report poorer health-related quality of life than healthy peers, with impairment in school, social and family domains that persists even when purging frequency is modest

Pathophysiology

• The leading psychological model is dietary restraint theory, in which overvaluation of shape and weight leads to rigid eating rules, and purging is used to compensate for perceived violations of those rules even without an objective binge
• Weight suppression, the difference between highest past weight and current weight, predicts the persistence of purging, and greater suppression is associated with stronger dietary restraint and a more chronic course
• Negative urgency, the tendency to act impulsively when distressed, is elevated in purging disorder and may explain why purging is used as a rapid emotion-regulation strategy after interpersonal stress or body-image triggers
• Neurobiological studies implicate altered serotonergic and dopaminergic signalling, prefrontal and striatal reward circuitry and disturbed interoception, but no biomarker has been validated for diagnosis or treatment selection
• Gut hormones such as ghrelin, leptin, peptide YY and cholecystokinin are altered in eating disorders and may contribute to altered satiety and purge initiation, although findings in purging disorder specifically are sparse and inconsistent
• Repeated vomiting and laxative misuse produce electrolyte loss, volume depletion and acid-base disturbance, and these peripheral consequences can reinforce fatigue, dizziness and palpitations that patients misattribute to food or weight

Clinical features

• The central behaviour is recurrent purging after eating, most often self-induced vomiting, and patients may also use laxatives, diuretics, enemas, appetite suppressants or excessive exercise to control weight
• Patients typically report feeling driven to purge after normal or small meals, describe shame and secrecy around the behaviour, and often schedule bathroom visits immediately after eating
• Physical signs of recurrent vomiting include Russell's sign with calluses or scars on the knuckles, dental enamel erosion, parotid gland swelling, subconjunctival haemorrhage and chronic sore throat
• Gastrointestinal features include heartburn, reflux, oesophagitis and, rarely, oesophageal rupture, while laxative misuse causes abdominal cramping, diarrhoea and dependence on laxatives for bowel movements
• Electrolyte disturbances such as hypokalaemia, hypochloraemia and metabolic alkalosis can produce weakness, cramps, arrhythmia and seizures, and dehydration may cause pre-renal kidney injury
• Psychiatric comorbidity is common and includes depression, anxiety disorders, obsessive-compulsive symptoms, self-harm and suicidal ideation, and body weight is usually normal, which can delay recognition by clinicians

Diagnosis

• The diagnosis is clinical and requires recurrent purging at least weekly for three months, undue influence of shape and weight, and the absence of binge eating, with symptoms not better explained by another medical or psychiatric condition
• A structured eating disorder interview such as the Eating Disorder Examination is the reference standard for quantifying purging frequency, restraint, shape and weight concerns and the absence of objective binge episodes
• Screening tools such as the SCOFF questionnaire can flag possible cases in primary care, but they do not distinguish purging disorder from bulimia nervosa and must be followed by a diagnostic interview
• Laboratory assessment includes electrolytes, magnesium, phosphate, renal function, glucose and, when vomiting is severe, an electrocardiogram to detect QT prolongation and arrhythmia risk from hypokalaemia
• The differential includes bulimia nervosa, the binge-purge subtype of anorexia nervosa, avoidant and restrictive food intake disorder, rumination disorder, cyclic vomiting syndrome, gastroparesis and laxative abuse for weight control
• Secondary causes of vomiting such as pregnancy, gastrointestinal obstruction, intracranial pathology and medication effects should be excluded before the diagnosis is made, and a dental examination is useful to document erosion

Management

• Care is multidisciplinary and combines nutritional rehabilitation, psychotherapy, medical monitoring and dental care, with the intensity of treatment determined by medical stability, purge frequency and psychiatric risk
• Enhanced cognitive behaviour therapy for eating disorders is the best-supported psychological treatment and targets overvaluation of shape and weight, dietary restraint, mood intolerance and purging triggers over approximately 20 sessions
• Interpersonal psychotherapy and, for adolescents, family-based treatment are reasonable alternatives, and dialectical behaviour therapy may help patients whose purging is driven by emotion dysregulation and self-harm
• No medication is approved specifically for purging disorder, and selective serotonin reuptake inhibitors such as fluoxetine are used off-label on the basis of evidence in bulimia nervosa, with monitoring for serotonergic adverse effects
• Electrolyte and volume replacement, antiemetic avoidance and treatment of arrhythmia or renal injury are medical priorities, and hospital admission is indicated for severe hypokalaemia, syncope, haematemesis or rapid weight loss
• Dental care includes fluoride application, desensitising toothpaste and restorative treatment for erosion, while behavioural advice such as avoiding tooth brushing immediately after vomiting reduces further enamel loss
• Relapse prevention addresses high-risk situations, body-image triggers, weight suppression and comorbid mood or anxiety disorders, and regular weighing and symptom monitoring should continue after discharge
• Prognosis is variable, with many patients improving under psychological treatment but a substantial minority running a chronic course, and the review of 11 deaths indicates that suicide risk must be assessed throughout care

Research and controversies

• Whether purging disorder should be a standalone diagnosis or remain within other specified feeding or eating disorder is the central nosological controversy, and the answer depends on evidence of distinct course, treatment response and neurobiology
• Studies comparing purging disorder with bulimia nervosa find differences in binge frequency, impulsivity, weight history and medical complications, but overlapping treatment response suggests that transdiagnostic approaches may be more useful than diagnostic boundaries
• Weight suppression and symptom sequencing are active research areas, and prospective work from Stice and colleagues in 2020 and 2021 suggests that dieting and weight loss precede purging and predict persistence rather than merely accompanying the disorder
• Male purging disorder, purging in midlife and purging in non-Western populations are under-represented in research, so current descriptions may not generalise to groups in which disclosure and treatment-seeking differ
• Digital interventions, including guided self-help and app-based cognitive behaviour therapy, are being tested as scalable options, but no trial has been powered to show non-inferiority to therapist-delivered treatment in purging disorder specifically