Anorexia Nervosa Medication

Updated: Jun 22, 2023
  • Author: Bettina E Bernstein, DO, DFAACAP, DFAPA; Chief Editor: Caroly Pataki, MD  more...
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Medication Summary

The use of medication in individuals with anorexia nervosa is limited to the treatment of medical complications, and the treatment of comorbid psychiatric conditions such as anxiety and depression that may impede psychosocial and behavioral treatments. To treat osteopenia and to prevent further bone loss, daily dietary intake of calcium 1000-1500 mg and vitamin D 400 IU are recommended. Estrogen replacement (ie, oral contraceptives) has also been recommended for the treatment of osteopenia, although the benefits and minimal effective dose is being explored. [109] Bisphosphonate therapy can be effective, but the patient should be closely monitored for osteonecrosis of the mandible. [100]

Evidence regarding the efficacy of medication treatment for eating disorders has tended to be weak or moderate, especially as side effects tend to limit long-term compliance compared with the time devoted to psychotherapeutic treatments. However, randomized, controlled trials have shown benefits from the use of medication in combination with cognitive behavioral therapy (CBT). [8, 9, 137]

Fluoxetine was found to be generally helpful in patients with anorexia nervosa who had been stabilized with weight restoration. Psychotherapy with adjunctive low-dose olanzapine may be useful for anorexia nervosa during inpatient treatment, especially in the context of anxiety, obsessive eating-related ruminations, and treatment resistance due to failure to engage. Higher-dose fluoxetine and/or topiramate may be helpful in bulimia nervosa. At this time, however, medication for weight loss in bulimia nervosa is not recommended, due to significant adverse effects such as pulmonary hypertension and heart failure. [8, 9]

In a meta-analysis of 8 studies involving 221 patients with anorexia nervosa, antipsychotics failed to show efficacy for body weight or other anorexia-related outcomes. [138]

Pharmacotherapy should not be the only line of treatment and should be used with caution in suspected bipolar disorder, but it may be helpful for depression. [139] Most patients who recover from anorexia nervosa will have been treated with a multidisciplinary approach that includes medication, psychotherapy, nutritional counseling, and frequent medical evaluations.

Antidepressive agents

Antidepressive and neuroleptic agents, although not reported to be effective, have a limited use in patients who have adequate nutrition and mood changes associated with anorexia nervosa. Prolongation of the QT interval is a contraindication to tricyclic antidepressants because a prolonged QT may increase the risk of ventricular tachycardia and death.


Selective serotonin reuptake inhibitors (SSRIs) have been shown to be beneficial in patients with bulimia nervosa but not anorexia. However, since many patients with anorexia have concurrent mood disorders, medication may be of benefit.

In patients with anorexia nervosa who have attained 85% of their expected weight, the SSRI fluoxetine has been used to stabilize recovery. Zinc and cyproheptadine have not been useful. SSRIs and serotonin norepinephrine reuptake inhibitors (SNRIs) may be more helpful for addressing concurrent obsessive-compulsive issues and, owing to their relative neutral effect on weight, may be more easily accepted by the patient.

SSRIs are greatly preferred over the other classes of antidepressants. [140] Because the adverse effect profile of SSRIs is less prominent, improved compliance is promoted. SSRIs do not have the cardiac arrhythmia risk associated with tricyclic antidepressants. Arrhythmia risk is especially pertinent in overdose, and suicide risk must always be considered in the treatment of a child or adolescent with a mood disorder.

Precautions in the pediatric population

Use appropriate caution when considering treatment with SSRIs in the pediatric population. In December 2003, the UK Medicines and Healthcare Products Regulatory Agency (MHRA) issued an advisory that most SSRIs are not suitable for use by persons younger than 18 years for treatment of "depressive illness." After review, this agency decided that the risks to pediatric patients outweigh the benefits of treatment with SSRIs, except fluoxetine, which appears to have a positive risk-benefit ratio in the treatment of depressive illness in patients younger than 18 years.

In October 2003, the US Food and Drug Administration (FDA) issued a public health advisory regarding reports of suicidality (ideation and attempts) in pediatric patients being treated with antidepressant medications for major depressive disorder and other conditions. The FDA asked, however, that additional studies be performed because suicidality occurred in treated and untreated patients with major depression and thus could not be definitively linked to drug treatment.

In 2005, the FDA proposed that manufacturers change antidepressant labeling by adding a black-box warning regarding the increased suicidality risk in children and adolescents who use antidepressants. The labeling change also emphasized the need for appropriate monitoring and patient awareness via medication guides. Two years later, the FDA also recommended updates on the black-box labeling of antidepressants regarding increased risk of suicidality in young adults aged 18-24 during initial treatment (generally the first 1-2 months).

A cohort study looked at suicide risk for youths younger than 24 years in the context of use of SSRIs and SNRIs and the current “Black Box” warning regarding increased risk of suicidal ideation in this population. [141] This retrospective cohort study included 36,842 children aged 6-18 years enrolled in Tennessee Medicaid from 1995-2006 who were new users of 1 of the antidepressant medications of interest (defined as filling no prescriptions for antidepressants in the preceding 365 days). It found that there was increased risk for suicide attempts among users of multiple antidepressants concomitantly; however, there was no evidence that risk of suicide attempts increased when one medication was prescribed and the adjusted rate of suicide attempts did not differ significantly among current users of SSRI and SNRI antidepressants compared with current users of fluoxetine.

The current evidence does not support an increased risk of suicide in patients with obsessive-compulsive disorder or other anxiety disorders who are treated with SSRIs.

Atypical antipsychotics

The atypical antipsychotics (eg, olanzapine, quetiapine, risperidone) have shown some benefit in the treatment of anorexia nervosa. This is thought likely to be from their effects on depression, anxiety, and core eating disordered psychopathology. However, there are significant safety concerns surrounding these drugs due to the high likelihood of cardiac conduction abnormalities in patients with anorexia. [139, 142]

Gastrointestinal prokinetic agents

Part of the pathophysiology of anorexia nervosa is a delay in gastric emptying, which can perpetuate the disorder by limiting the quantity of food that can be eaten. Although a study of cisapride (Propulsid) did not show gastric-emptying enhancement, participants reported a greater improvement in subjective symptoms during a meal. [143]

In 2000, however, cisapride use in patients with anorexia nervosa or bulimia was discouraged after cisapride was found to be associated with serious cardiac events (ie, serious arrhythmias associated with prolonged QTc) and the risk of cardiovascular-related events in patients with eating disorders.


Electrolyte Supplements

Class Summary

Electrolyte repletion is necessary in patients with profound malnutrition, dehydration, and purging behaviors. Repletion may be done orally or parenterally, depending on the patient’s clinical state.

Calcium carbonate (Tums, Oysco, Os-Cal, Maalox)

Calcium moderates nerve and muscle performance by regulating the action potential excitation threshold. It also improves bone density.

Potassium chloride (K-Lor, Klor-Con, Micro-K)

Potassium is essential for the transmission of nerve impulses, contraction of cardiac muscle, maintenance of intracellular tonicity, skeletal and smooth muscle contraction, and maintenance of normal renal function. Gradual potassium depletion occurs via renal excretion or gastrointestinal loss or because of low intake. Depletion usually results from diuretic therapy, primary or secondary hyperaldosteronism, diabetic ketoacidosis, severe diarrhea (if associated with vomiting), or inadequate replacement during prolonged parenteral nutrition.

Potassium depletion sufficient to cause 1 mEq/L drop in the serum potassium level requires a loss of approximately 100-200 mEq of potassium from the total body store.

Calcium gluconate (Cal-Glu)

Calcium gluconate moderates nerve and muscle performance and facilitates normal cardiac function. It can initially be given intravenously, and then calcium levels can be maintained with a high-calcium diet. Some patients require oral calcium supplementation. The 10% intravenous (IV) solution provides 100 mg/mL of calcium gluconate, equaling 9 mg/mL (0.46 mEq/mL) of elemental calcium. One 10-mL ampule contains 93 mg of elemental calcium.

Potassium phosphates, IV

For severe hypophosphatemia (< 1 mg/dL), parenteral preparations of phosphate should be used for repletion. IV preparations are available as sodium or potassium phosphate (K2PO4). Response to IV serum phosphorus supplementation is highly variable and is associated with hyperphosphatemia and hypocalcemia. The rate of infusion and choice of initial dosage should be based on the severity of hypophosphatemia and the presence of symptoms. Serum phosphate and calcium should be monitored closely.

For less severe hypophosphatemia (1-2 mg/dL), oral phosphate salt preparations can be used. Oral preparations are available as sodium or potassium phosphate in capsule or liquid form. Neutra-Phos packets each contain 250 mg of phosphorus; tablets contain 250, 125.6, or 114 mg. Liquid preparations are available as 250 mg/75 mL.


Vitamins, Fat Soluble

Class Summary

Vitamins are used to meet necessary dietary requirements. They are utilized in metabolic pathways, as well as in deoxyribonucleic acid (DNA) and protein synthesis.

Ergocalciferol (Calciferol, Drisdol, Calcidol)

This is a vitamin D-2 analogue that is converted in the liver to an active intermediate and then further converted to its most active form in the kidneys. It stimulates the absorption of calcium and phosphate from the small intestine and promotes the release of calcium from bone into blood. Because it is a precursor, a significant delay between dose administration and effect exists. The liver must be intact for the intermediate to be formed (calcidiol, 25-hydroxy vitamin D). Many drugs may affect this step.

Ergocalciferol is stored in fat, so when there is a lack of fat (due to weight loss), the potential exists for overdose of ergocalciferol. It has lipid storage, so overdoses may cause prolonged hypercalcemia.

Ergocalciferol is used as a replacement therapy. To measure of its efficacy, assess the serum calcium concentration.


Antidepressants, SSRIs

Class Summary

These agents have been reported to reduce binge eating, vomiting, and depression and to improve eating habits, although their impact on body dissatisfaction remains unclear.

Fluoxetine (Prozac)

Fluoxetine selectively inhibits presynaptic serotonin reuptake, with minimal or no effect on the reuptake of norepinephrine or dopamine. It may cause more adverse gastrointestinal effects than other currently available SSRIs, which is the reason it is not recommended as a first choice.

Fluoxetine can be administered as a liquid or a capsule and can be given in single or divided doses. The presence of food does not appreciably alter levels of the medication. It may take up to 4-6 weeks to achieve steady-state levels of the medication because it has a long half-life (72 h). The long half-life is both an advantage and a drawback. If fluoxetine works well, an occasional missed dose is not a problem; if fluoxetine-related problems occur, however, eliminating all active metabolites takes a long time.

The choice to use fluoxetine depends on adverse effects and drug interactions. Adverse effects of SSRIs seem to be quite idiosyncratic; thus, relatively few reasons exist to prefer one over another at this point if dosing is started at a conservative level and advanced as tolerated.

Fluoxetine is indicated for the treatment of binge eating and self-induced vomiting in patients with moderate to severe bulimia nervosa. The drug's antidepressant, anti–obsessive-compulsive, and antibulimic actions are presumed to be linked to inhibition of the central nervous system's uptake of serotonin.