Clonazepam and Weight Gain
Clonazepam (a benzodiazepine) is generally considered weight-neutral and does not cause clinically significant weight gain. The FDA drug label for clonazepam lists both weight loss and weight gain as possible adverse effects occurring in less than 1% of patients, indicating no consistent directional effect on body weight 1.
Evidence-Based Assessment
Benzodiazepines are weight-neutral medications. The comprehensive 2017 Gastroenterology guidelines on pharmacotherapy for obesity extensively reviewed medication classes associated with weight changes, including antidepressants, antipsychotics, antiepileptics, antihypertensives, and antihistamines—but notably did not identify benzodiazepines as a weight-promoting drug class 2. A 2013 systematic review specifically confirmed that benzodiazepines are weight-neutral 3.
Clinical Context: What Actually Causes Weight Gain
The confusion likely stems from medications that DO cause substantial weight gain:
Antipsychotics: Clozapine and olanzapine cause the most significant weight gain (averaging 7.5-11 kg over 12 months), while quetiapine and risperidone also consistently promote weight gain 2, 4, 5, 6
Antidepressants: Paroxetine (highest risk among SSRIs), amitriptyline (highest among tricyclics), mirtazapine, lithium, and MAO inhibitors are closely associated with weight gain 2, 7, 8
Antiepileptics: Gabapentin, pregabalin, valproic acid, and carbamazepine consistently cause weight gain 2
Other medications: Beta-blockers, alpha-blockers, thiazide diuretics, oral glucocorticoids, and certain hormonal contraceptives promote weight gain 2
Important Clinical Caveat
If a patient on clonazepam experiences weight gain, investigate other causes first:
- Review all concurrent medications, particularly antipsychotics, mood stabilizers, or antidepressants that are known weight-promoting agents 2
- Assess for underlying psychiatric conditions (depression, anxiety) that may independently affect appetite and activity levels 2
- Evaluate lifestyle factors including dietary changes, reduced physical activity, or metabolic conditions 2
Bottom Line for Clinical Practice
Clonazepam should not be discontinued or avoided due to weight concerns. The medication itself does not cause clinically meaningful weight changes, and any weight fluctuations observed are likely multifactorial or related to other medications 1, 3.