Shared genetic architecture with mood disorders and substance use
Pathophysiology
Purging-driven electrolyte derangements
Vomiting mechanism
Loss of hydrochloric acid from gastric secretion
Results in hypochloremic metabolic alkalosis
Compensatory aldosterone activation worsens K+ loss
Volume depletion activates renin-angiotensin system perpetuating alkalosis
Laxative abuse mechanism
Loss of bicarbonate-rich colonic fluid
Results in hyperchloremic metabolic acidosis
Potassium lost in stool; osmotic agents less damaging than stimulant laxatives
Diuretic abuse mechanism
Loop or thiazide diuretics cause K+ and Mg2+ loss
Volume depletion and secondary hyperaldosteronism
Cardiac pathophysiology
Hypokalemia cardiac effects
Hyperpolarizes myocardial cell membrane
Prolongs action potential duration and QTc
Increases automaticity and re-entry arrhythmia risk
U waves on ECG from altered repolarization
Ipecac cardiomyopathy
Emetine directly toxic to cardiac and skeletal myocytes
Irreversible mitochondrial damage with chronic use
Reduces ejection fraction; may cause CHF
Dental and GI pathophysiology
Dental enamel erosion
Gastric acid (pH <2.0) demineralizes enamel
Lingual surfaces of upper anterior teeth preferentially affected
Perimolysis (acid erosion from vomiting) irreversible
Sialadenosis
Autonomic stimulation from repeated vomiting enlarges parotid glands
Non-inflammatory; bilateral painless swelling
GI mucosal damage
Esophagitis from repetitive acid exposure
Barrett esophagus risk from chronic GERD
Mallory-Weiss tears at gastroesophageal junction
Boerhaave syndrome: full-thickness rupture from extreme intragastric pressure
Neurobiology
Serotonin system dysregulation
5-HT1A and 5-HT2A receptor alterations
Impaired satiety signaling
Basis for fluoxetine efficacy
Dopamine and reward dysregulation
Binge eating activates mesolimbic reward pathways similar to addiction
Explains compulsive quality of binge episodes
HPA axis dysregulation
Elevated cortisol with active purging
Contributes to bone loss and immune suppression
Therapeutic Considerations
Evidence base for pharmacotherapy
Fluoxetine 60 mg/day
Only FDA-approved pharmacotherapy for bulimia nervosa
Multiple RCTs demonstrate reduction in binge-purge frequency
Number needed to treat approximately 4-5 for remission
APA Practice Guideline recommends as first-line pharmacotherapy (2023)
Inferior to CBT alone; combined CBT + fluoxetine superior to either alone
Other antidepressants
SSRIs (sertraline, citalopram) used off-label when fluoxetine not tolerated
Avoid bupropion in all patients with bulimia nervosa
MAOIs: efficacy evidence exists but rarely used due to safety profile
Evidence base for psychotherapy
CBT-BN
Strongest evidence; remission rates 30-50% in RCTs
Targets cognitive distortions and behavioral patterns
ACEP Level A equivalent for psychosocial interventions
Guided self-help CBT
Effective for mild-moderate severity when therapist access limited
NICE guideline recommended first step in care pathway
Long-term outcome
Recovery rates
50-70% achieve full recovery with treatment over 10 years
Higher recovery rates than anorexia nervosa
Relapse common; ongoing monitoring required
Untreated course
Chronic relapsing illness; spontaneous remission possible but uncommon
Transition to anorexia nervosa in 10-15% over time
Cumulative medical complications worsen with duration of illness
Hospitalization indications per APA 2023 guidelines
Medical instability as primary driver
Outpatient or residential treatment preferred when medically stable
Patient Discharge Instructions
copy discharge instructions
Discharge instructions for bulimia nervosa
Your diagnosis
You were treated for bulimia nervosa with medical complications
Your electrolytes (blood salts) were low and have been corrected
It is very important to follow up with your doctors to keep these levels normal
Medications
Take all prescribed medications as directed
Do not stop or change your medications without talking to your doctor
If prescribed fluoxetine (Prozac), it may take several weeks to notice improvement
Eating and drinking
Try to eat regular, balanced meals 3 times a day plus snacks
Avoid skipping meals as this can trigger binge episodes
Drink adequate fluids to stay hydrated
Work with a registered dietitian experienced in eating disorders
Important side effects to know about
If you stop laxatives or diuretics, you may notice temporary swelling in your legs
This swelling is normal and will go away on its own within 2-4 weeks
This swelling does not mean you are gaining weight permanently
Dental care
See a dentist as soon as possible for assessment of your teeth
After vomiting, rinse with water or a fluoride rinse but do not brush immediately
Brushing immediately after vomiting worsens enamel damage
Mental health support
Attend your psychiatry or therapy appointments
Cognitive behavioral therapy (CBT) is the most effective treatment for bulimia nervosa
Recovery is achievable; most people with bulimia nervosa do recover with treatment
Appointments to keep
Blood work recheck within 48-72 hours (electrolytes)
Follow up with your family doctor or eating disorder clinic within 1 week
Return to the emergency department immediately if you experience
Palpitations, irregular heartbeat, or fainting
Vomiting blood or material that looks like coffee grounds
Severe chest pain or difficulty swallowing
Severe muscle weakness or inability to walk
Seizure
Thoughts of harming yourself or suicide
Inability to keep any fluids down
References
Guidelines and key sources
Primary guidelines
American Psychiatric Association Practice Guideline for Eating Disorders (2023)
Crone C, Fochtmann LJ, Attia E, et al. American Journal of Psychiatry. 2023
Comprehensive guideline for pharmacotherapy and psychotherapy
AAP Clinical Report: Identification and Management of Eating Disorders in Children and Adolescents
Hornberger LL, Lane MA. Pediatrics. 2021
Admission criteria and adolescent-specific management
USPSTF Recommendation: Screening for Eating Disorders in Adolescents and Adults (2022)
Davidson KW, Barry MJ, et al. JAMA. 2022
Grade B recommendation for screening
Landmark studies and reviews
Key evidence
Attia E, Walsh BT. Eating Disorders: A Review. JAMA. 2025
Comprehensive review of diagnosis and management across eating disorders
Treasure J, Duarte TA, Schmidt U. Eating Disorders. Lancet. 2020
Epidemiology, pathophysiology, and treatment evidence
Tith RM, Paradis G, Potter BJ, et al. Association of Bulimia Nervosa With Long-term Risk of Cardiovascular Disease and Mortality Among Women. JAMA Psychiatry. 2020
Women with bulimia nervosa have greater than 4x risk of CVD and premature death
Krantz MJ, Blalock DV, Tanganyika K, et al. Is QTc-Interval Prolongation an Inherent Feature of Eating Disorders? American Journal of Medicine. 2020
QTc prolongation driven by hypokalemia and QTc-prolonging medications not intrinsic to eating disorder; cohort of 906 patients
Hundemer GL, Clarke A, Akbari A, et al. Analysis of Electrolyte Abnormalities in Adolescents and Adults and Subsequent Diagnosis of an Eating Disorder. JAMA Network Open. 2022
Unexplained hypokalemia and hypochloremia predictors of subsequent eating disorder diagnosis
Mehler PS. Bulimia Nervosa. NEJM. 2003
Classic clinical review; medical complications and management
Klein DA, Sylvester JE, Schvey NA. Eating Disorders in Primary Care: Diagnosis and Management. American Family Physician. 2021
Primary care approach including SCOFF questionnaire and management algorithms
SymptomDx is an educational tool for medical professionals. It does not replace clinical judgment. Verify all clinical data and drug dosages with authoritative sources.