Does Clonazepam Cause Hyponatremia?
Clonazepam is not documented to cause hyponatremia based on FDA labeling and available evidence. The official FDA drug label for clonazepam does not list hyponatremia as a known adverse effect 1.
Evidence from FDA Drug Labeling
The comprehensive FDA adverse reaction profile for clonazepam includes extensive listings of side effects across multiple organ systems, but hyponatremia is notably absent 1. The documented adverse effects include:
- CNS effects: Drowsiness (50%), ataxia (30%), behavioral problems (25%)
- Metabolic effects: Dehydration, weight changes
- Hepatic effects: Transient transaminase elevations
- Hematologic effects: Anemia, leukopenia, thrombocytopenia
- Renal effects: Dysuria, enuresis, urinary retention
However, electrolyte disturbances, specifically hyponatremia, are not mentioned 1.
Context: Benzodiazepines and Hyponatremia
While psychotropic medications as a class are associated with hyponatremia 2, 3, 4, 5, the evidence primarily implicates:
- Antidepressants (especially SSRIs)
- Antipsychotics
- Anticonvulsants (carbamazepine, oxcarbazepine)
- Thiazide diuretics
These medications typically cause hyponatremia through syndrome of inappropriate antidiuresis (SIAD) 6.
Important Clinical Caveat
One case report describes lorazepam (another benzodiazepine) being used to treat severe hiccups that were causing SIADH, with resolution of hyponatremia after lorazepam administration 7. This suggests benzodiazepines may not have intrinsic hyponatremia-inducing properties.
Clinical Recommendation
If hyponatremia develops in a patient taking clonazepam, look for alternative causes first:
- Concurrent medications (SSRIs, thiazides, antipsychotics, anticonvulsants)
- Underlying medical conditions
- Volume status abnormalities
- Other psychotropic agents
The risk factors for drug-induced hyponatremia include advanced age, female gender, polypharmacy, and medical comorbidity 2, 3. If these are present, scrutinize all medications, but clonazepam itself is unlikely to be the culprit based on current evidence.