Mental Health

Bulimia nervosa

An eating disorder with recurrent binge episodes, loss of control and regular compensatory behaviour, often at a normal weight but with potentially dangerous electrolyte, cardiac, dental and gastrointestinal complications.

In a nutshell

Bulimia nervosa is recurrent binge eating with loss of control and regular compensatory behaviour, often at a normal weight. Vomiting or laxative misuse can cause hypokalaemia, metabolic disturbance, renal injury and arrhythmia. Stabilise acute physical risk, then offer CBT-based guided self-help followed by eating-disorder-focused CBT; medication is adjunctive, not sole treatment.

Classic presentation

A person of apparently normal weight who binges in secret and then vomits or misuses laxatives, with weight and shape preoccupation, dental erosion, parotid swelling or knuckle calluses.

Key points

A normal BMI does not exclude bulimia or serious medical risk.
Ask directly about vomiting, laxatives, diuretics, fasting and driven exercise; compensation may be concealed.
Hypokalaemia, metabolic alkalosis, dehydration, renal dysfunction and QT prolongation are urgent risk findings.
Guided self-help based on CBT is an initial adult treatment, stepping up to eating-disorder-focused CBT if required.
Children and young people are usually offered bulimia-focused family therapy with specialist alternatives where needed.
Medication is not sole treatment; review QT and electrolyte risks before prescribing.
Reassess for anorexia if significant restriction, low weight or starvation physiology emerges.

First-line investigation

Detailed binge and compensation history, pulse and postural observations, U&E including potassium and bicarbonate, renal function and ECG, alongside mental-health and safeguarding assessment.

Management

Identify purging and acute medical risk

Ask directly about bingeing, vomiting, laxatives, diuretics, fasting and driven exercise, and urgently assess collapse, weakness, dehydration, electrolytes, renal function and ECG.^1,3,2

Refer to specialist eating-disorder care

Refer promptly even when weight is normal, and assess depression, self-harm, suicide, pregnancy, diabetes, substance use and safeguarding.^1,2,5

Start CBT-based guided self-help

Offer bulimia-focused guided self-help for adults, supporting regular eating, trigger work, monitoring and interruption of post-meal compensation.^1,2

Step up to psychological therapy and address consequences

If guided self-help is unsuitable or ineffective, offer CBT-ED; add dietetic, dental, medical and psychiatric care as needed.^1,2

Adapt family and medication care

Use family-focused treatment for children and young people; medication is never sole treatment and requires BNF review when electrolytes or QT are abnormal.^1,7,6

Monitor and safety-net

Repeat physical and mental-health review according to risk, give urgent escalation advice, and reassess if restriction or starvation features emerge.^1,3,2

Exam traps

Russell’s sign and dental erosion are clues, not required diagnostic criteria.
Hypokalaemia from vomiting is an arrhythmia risk even when the person is not underweight.
Medication must not replace psychological therapy.
Laxative misuse can cause serious electrolyte and renal complications; do not assume it is harmless because it is purchased over the counter.
Weight loss, marked restriction or bradycardia should trigger assessment for anorexia nervosa or another high-risk eating disorder.

Illustrations

Russell’s signClinical photograph showing callus and abrasion over the knuckles from repeated self-induced vomiting; it is a clue, not a required feature.Kyukyusha, Wikimedia Commons · Public domain

Key sources

This page is exam revision material, not medical advice, and must not be used for patient care. Always check drug doses against the BNF and current guidance. Full disclaimer.