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OverviewAetiologyPathophysiologyClinical features and red flagsInvestigationsDifferential diagnosisManagementComplicationsMonitoring and follow-upSpecial situationsCommon pitfallsQuestionsSources
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Educational draft · awaiting clinical reviewThe full textbook explains uncertainty but does not replace live national or local guidance, specialist advice, or current prescribing information.

Bulimia nervosa and binge-eating disorder

Psychiatry · UK scope · Sources checked 27 Aug 2026 · Clinical review pending

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Purging with electrolyte or gastrointestinal danger

Collapse, arrhythmia, severe weakness, seizure, haematemesis, severe chest or abdominal pain, confusion, potassium below 2.5 mmol/L, severe dehydration or suicide risk require emergency assessment regardless of BMI.

Action: Assess ABCDE and glucose, obtain ECG, electrolytes including magnesium and phosphate, renal function and senior medical review, and treat the complication in an acute setting. Involve eating-disorder and mental-health services early; do not discharge after transient symptom relief without a plan for continued purging risk.

Overview

Distinguish bulimia nervosa from binge-eating disorder, identify concealed purging and acute complications at any weight, and use NICE psychological pathways with safe adjunctive prescribing.

Bulimia nervosa and binge-eating disorder share recurrent episodes of loss of control over eating but differ in what follows. Bulimia includes regular compensatory behaviour intended to offset intake or influence weight and shape. Binge-eating disorder lacks that regular compensation; people may experience shame, rapid eating, eating when not hungry and distress afterwards. Avoid assuming that every large meal is a binge or that every person in a larger body has binge-eating disorder. Ask how control felt and whether the episode was unusual for the context.

Assessment should be behaviourally specific. Ask about vomiting, fasting, exercise, laxatives, diuretics, thyroid products, stimulants, supplements and manipulation of insulin or other medication. Establish frequency, recent escalation, triggers and what happens before and after an episode. Explore dental symptoms, reflux, chest or abdominal pain, bowel change, menstrual or endocrine symptoms and syncope. Ask about depression, anxiety, trauma, alcohol, substances, self-harm and suicide, which can alter both treatment and immediate safety.

Practice

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PsychiatryOriginal SBA

Binge-eating treatment target

An adult with binge-eating disorder asks to start a strict weight-loss diet during focused psychological treatment. Which response best matches NICE guidance?

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Sources and review status4 sources · checked 27 Aug 2026 · clinical review pending+
Sources

Sources and review status

National guidance is shown before implementation-dependent detail. Typical adult dose examples remain subject to patient factors, contraindications and the live BNF or specialist protocol. Source check completed 27 Aug 2026; clinical approval remains outstanding.

  • NICE NG69 eating disorders recommendationsStepped psychological treatment and physical-risk assessment.
  • RCPsych CR233 Medical Emergencies in Eating DisordersPurging, electrolyte, gastrointestinal and emergency management.
  • Fluoxetine 60 mg capsules UK SmPCAdult bulimia indication, dose and duration evidence.
  • NHS eating disorders overviewCurrent descriptions and routes to care.

Editorial contact: Doctor’s Passport editorial team. Source-check date is separate from clinical approval. Report a content problem · Content changes

Authoring stateComplete draftClinical stateAwaiting reviewJurisdictionUnited Kingdom
Purging can cause major medical illness at any weight. Vomiting commonly produces chloride and potassium depletion with metabolic alkalosis; diarrhoeal laxative misuse may produce bicarbonate loss and metabolic acidosis. Dehydration activates renal and hormonal conservation, and stopping purging can temporarily cause oedema. Dental erosion, parotid enlargement and knuckle callus may occur but their absence does not exclude behaviour. Severe chest pain or haematemesis warrants assessment for oesophageal or gastric injury.

NICE treatment begins with eating-disorder-focused psychological approaches. Guided self-help uses structured cognitive behavioural material plus brief support. CBT-ED establishes regular meals and snacks, reduces rigid dieting, maps emotional and situational triggers, addresses body-image beliefs where relevant and plans relapse prevention. For binge-eating disorder, dieting during treatment can trigger further binges, and patients should understand that stopping binges rather than immediate weight loss is the target. Weight-related healthcare should remain respectful and separately agreed.

Medication cannot replace psychotherapy or nutritional work. A current UK fluoxetine SmPC recommends 60 mg daily for adults with bulimia as a complement to psychotherapy, while noting that efficacy beyond 3 months has not been demonstrated. Before prescribing, review potassium, sodium, QT risk, other serotonergic or QT-prolonging drugs, overdose risk, bipolar history and adherence. NICE does not recommend medication as the sole treatment for bulimia or binge-eating disorder.

Key points

  • A binge is an episode of eating with loss of control; quantity, context, speed, secrecy and subjective experience should be explored without moral language.
  • Bulimia nervosa includes recurrent binge eating with compensatory behaviour such as vomiting, fasting, excessive exercise or misuse of laxatives, diuretics or other treatment, alongside weight-shape overvaluation.
  • Binge-eating disorder has recurrent distressing binge episodes without the regular compensatory pattern that defines bulimia; weight loss is not the psychological-treatment target.
  • Both conditions occur across the weight range, and serious bulimia complications may be invisible during routine examination.
  • Check fluid and electrolytes when purging is suspected and use ECG according to rapid loss, severe purging, bradycardia, hypotension, electrolyte disturbance, exercise and medication risk.
  • For adults with binge-eating disorder, NICE offers focused guided self-help, followed by group CBT-ED if unacceptable or ineffective after 4 weeks; individual CBT-ED is an alternative when group treatment is unavailable or declined. Offer children and young people the same treatments, adapted to development.
  • For adult bulimia, consider focused guided self-help and, if unacceptable, contraindicated

Aetiology

01

Dietary restraint

Rigid restriction increases physiological hunger and attentional capture by food, making loss-of-control eating more likely when rules break.

02

Affect regulation

Bingeing or purging may briefly alter distress, shame, numbness or interpersonal tension, which reinforces repetition despite later guilt.

03

Multiple vulnerabilities

Genetic liability, trauma, anxiety, impulsivity, weight stigma and social learning interact differently for each person and never justify blame.

Pathophysiology

  1. 1
    Potassium depletion

    Vomiting, diarrhoea and diuretics lower total-body potassium, increasing weakness, renal injury, QT-related arrhythmia and sudden death risk.

  2. 2
    Acid-base change

    Vomiting usually removes gastric acid and chloride, causing alkalosis, whereas substantial laxative diarrhoea can cause bicarbonate loss and acidosis.

  3. 3
    Volume conservation

    Repeated dehydration activates sodium-retaining systems, contributing to postural symptoms and rebound oedema when purging suddenly stops.

  4. 4
    Binge reinforcement

    Restriction and emotional cues increase binge vulnerability; compensation then reduces immediate fear but restores deprivation and perpetuates the sequence.

Clinical features and red flags

Loss-of-control eating

The central experience is inability to stop or regulate eating during an episode, interpreted alongside amount, context, speed, secrecy and distress.

Compensatory cycle

Restriction, vomiting, fasting, exercise or medication misuse temporarily reduces fear after a binge and then increases hunger, shame and future vulnerability.

Binge eating without purging

Recurrent distressing binges without regular compensatory behaviour point toward binge-eating disorder rather than bulimia, although mixed or changing patterns occur.

Physical clues

Dental erosion, parotid swelling, Russell-type knuckle callus, reflux, postural symptoms and oedema support investigation but are neither necessary nor specific.

Concealed treatment manipulation

Insulin, diuretics, laxatives and supplements may be altered for weight control; neutral direct questions are safer than waiting for disclosure.

Red flags requiring action

  • Syncope, palpitations, chest pain or muscle weakness after vomiting, laxatives or diuretics may indicate hypokalaemia or arrhythmia and needs urgent ECG and bloods.
  • Haematemesis, sudden severe chest pain, surgical abdominal signs or subcutaneous emphysema raises concern for mucosal tear or gastrointestinal perforation.
  • Seizure or confusion may follow severe sodium disturbance from water loading, dehydration or rapid electrolyte change.

Investigations

  1. 01
    Behavioural eating assessmentFirst step
    Why
    Characterise binge experience, compensation, dietary restraint, triggers and weight-shape overvaluation.
    Interpretation and limitations
    Diagnosis depends on the pattern and function over time; a screening questionnaire, body size or one overeating episode is insufficient.
  2. 02
    Fluid and electrolyte profile
    Why
    Detect potassium, sodium, chloride, bicarbonate, renal, magnesium and phosphate abnormalities from purging or restriction.
    Interpretation and limitations
    Hypokalaemic alkalosis supports vomiting or diuretic loss, while laxative diarrhoea may cause acidosis; normal results do not exclude intermittent dangerous behaviour.
  3. 03
    Twelve-lead ECG
    Why
    Identify rhythm or QTc consequences of electrolytes, bradycardia and medication.
    Interpretation and limitations
    Interpret with symptoms, rate and drug exposure; severe hypokalaemia, prolonged QTc or arrhythmia needs urgent correction and monitoring.
  4. 04
    Focused physical and dental review
    Why
    Assess circulation, hydration, oral injury, parotids, abdomen and complications of vomiting.
    Interpretation and limitations
    A normal examination cannot rule out purging, while haematemesis or severe chest and abdominal signs changes the pathway to acute medical care.

Differential diagnosis

01

Ordinary overeating

A large celebratory or culturally expected meal without loss of control or recurrent distress is not itself a binge-eating disorder.

02

Anorexia binge-purge subtype

Bingeing and purging can occur in anorexia when significantly low weight and the broader restrictive syndrome are present.

03

Gastrointestinal disease

Reflux, obstruction, gastroparesis and vomiting disorders need consideration when emesis is involuntary or not linked to compensation.

04

Mood-related appetite change

Depression, mania, substances and medication may alter appetite or impulsivity without the characteristic recurrent eating-disorder pattern.

Management

01Initial presentationName the binge-purge patternFirst stepLoss-of-control eating, secretive episodes, vomiting or weight-control behaviours are reported or suspected.+
  1. 1Ask non-judgementally about binges, every compensatory method, diet rules, triggers, impairment and the person's goals.
  2. 2Assess physical health, fluid and electrolyte risk, ECG indications, dental needs and current suicide or self-harm risk.
  3. 3Refer immediately to an age-appropriate eating-disorder service and provide clear emergency return advice.
02Adult treatmentUse the stepped NICE routeBulimia or binge-eating disorder is confirmed and there is no current need for medical admission.+
  1. 1Offer or consider the disorder-focused guided self-help approach specified by NICE and support adherence rather than adding generic dieting.
  2. 2Review after 4 weeks; move to the relevant CBT-ED programme when self-help is unacceptable,

Complications

01

Cardiac arrhythmia

Hypokalaemia, hypomagnesaemia, dehydration and QT-active medicines can combine to produce syncope, ventricular arrhythmia and sudden death.

02

Upper gastrointestinal injury

Repeated vomiting causes reflux and mucosal tears; severe pain, bleeding or systemic illness raises concern for perforation.

03

Dental and salivary harm

Acid exposure erodes enamel and can enlarge parotid glands, while brushing immediately after vomiting may worsen abrasion.

04

Psychosocial entrapment

Secrecy, shame, financial cost and social avoidance can substantially intensify depression, occupational impairment and suicide risk.

Monitoring and follow-up

  • Track binge and compensatory frequency, regular eating, triggers, distress and functional recovery rather than focusing only on body weight.
  • Repeat electrolytes and ECG according to purging intensity, symptoms, previous abnormalities and medication; escalate promptly when behaviour increases.
  • Review dental erosion, reflux, bowel symptoms and misuse of laxatives, diuretics, insulin, supplements or stimulants without shaming disclosure.
  • When fluoxetine is used, assess response, adherence, adverse effects, interactions and ongoing need; it remains adjunctive to psychotherapy.
  • Maintain a relapse plan covering renewed restriction, secretive eating, exercise, vomiting, medication manipulation, self-harm and routes for rapid re-entry to care.

Special situations

Weight does not screen risk

Bulimia may cause life-threatening potassium or gastrointestinal complications in someone whose body size appears unchanged or high.

Laxatives do not remove calories

Most energy absorption occurs before laxatives act; misuse mainly changes water and electrolytes while reinforcing the compensatory cycle.

Oedema can follow cessation

Hormonal sodium retention after repeated purging may produce transient rebound oedema, which needs explanation to prevent renewed harmful behaviour.

BED therapy is not dieting

Regular eating and trigger work reduce binges; pursuing weight loss during focused treatment can recreate deprivation and loss of control.

Confidentiality supports disclosure

Explain its limits, offer private time to younger people and involve supporters thoughtfully so hidden behaviours can be discussed safely.

Common pitfalls

  1. 01

    Equating a binge with any large meal without establishing loss of control and context.

  2. 02

    Diagnosing binge-eating disorder while overlooking regular vomiting, fasting or compulsive exercise.

  3. 03

    Reassuring on the basis of BMI or a single normal potassium result despite ongoing purging.

  4. 04

    Giving weight-loss dieting advice during focused treatment for binge-eating disorder.

  5. 05

    Prescribing fluoxetine as a replacement for CBT-ED or without checking electrolyte and interaction risk.

  6. 06

    Stopping care after acute potassium correction without addressing suicide risk and the binge-purge cycle.

or ineffective after 4 weeks, individual CBT-ED. For children and young people, offer FT-BN first and consider individual CBT-ED if FT-BN is unacceptable,
contraindicated
or ineffective.
  • Fluoxetine 60 mg daily has a UK adult indication as a complement to psychotherapy for reducing bingeing and purging, but medication is not sole treatment and physical risk modifies prescribing.
  • Insulin omission or underdosing for weight control risks diabetic ketoacidosis and requires immediate diabetes and eating-disorder expertise.
  • Escalating binge-purge frequency, self-poisoning, suicidal intent or inability to interrupt behaviour needs same-day psychiatric and physical review.
    • 05
    Comorbidity and safety formulation
    Why
    Identify mood, trauma, substances, diabetes treatment manipulation, self-harm and suicide risk.
    Interpretation and limitations
    Treat coexisting problems alongside the eating disorder, coordinating services when substance use or medical illness interferes with safe therapy.
    contraindicated
    or ineffective.
  • 3If fluoxetine is considered for adult bulimia, use it only as an adjunct, review physical and interaction risks and define a response review point.
    • 03Acute complicationTreat physiology before dischargePurging is accompanied by collapse, ECG change, severe blood abnormality, bleeding or acute pain.+
    1. 1Stabilise ABCDE and glucose, stop causative medicines where appropriate and obtain senior acute medical input.
    2. 2Correct electrolyte and fluid abnormalities with monitoring appropriate to severity; consider gastrointestinal or cardiac specialist review for alarm features.
    3. 3Arrange eating-disorder and psychiatric follow-up before discharge because correction of one blood result does not stop the maintaining cycle.
    Key medicines and prescribing safety1 treatment · regimens, roles and cautions+
    May reduce binge-eating and purging activity while the person receives structured psychological treatment.

    Fluoxetine

    For adult bulimia nervosa, 60 mg orally once daily as a complement to psychotherapy; reassess benefit because efficacy beyond three months is not established.

    Not sole treatment; review suicidality, bipolarity, interactions, sodium, bleeding risk and seizure risk, and correct electrolyte or QT hazards before prescribing.