Can Terbinafine (antifungal medication) cause hyponatremia (low sodium levels)?

Terbinafine and Hyponatremia

Based on current evidence, terbinafine is not known to cause hyponatremia as a recognized adverse effect. The British Association of Dermatologists' guidelines for onychomycosis do not list hyponatremia among terbinafine's documented side effects 1.

Known Side Effects of Terbinafine

Terbinafine is generally well tolerated, but does have documented adverse effects:

• Gastrointestinal disturbances (49% of reported side effects) including nausea, diarrhea, and taste disturbance 1
• Dermatological events (23% of reported side effects) such as rash, pruritus, urticaria, and eczema 1
• Rare serious adverse reactions including Stevens-Johnson syndrome and toxic epidermal necrolysis 1
• Rare hepatic toxicity, particularly in patients with pre-existing liver disease 1
• Very rare taste disturbance that can potentially be permanent 1
• Rare cases of rhabdomyolysis that can lead to acute kidney injury 2

Electrolyte Abnormalities and Terbinafine

• The comprehensive British Association of Dermatologists' guidelines for onychomycosis (2014) do not mention hyponatremia as a side effect of terbinafine 1
• A recent analysis of drug-induced hyponatremia cases from the Spanish Pharmacovigilance System (2024) did not identify terbinafine among medications associated with hyponatremia 3
• The review of drug-induced hyponatremia does not list terbinafine as a causative agent 4

Clinical Monitoring Recommendations

When prescribing terbinafine, the following monitoring is recommended:

• Baseline liver function tests and complete blood count in patients with:
  • History of heavy alcohol consumption 1
  • Hepatitis 1
  • Hematological abnormalities 1
  • Children (as terbinafine is not licensed for pediatric onychomycosis) 1
• Monitor for drug interactions, particularly with medications metabolized by cytochrome P450 2D6 isoenzyme 1, 5
• Avoid use in patients with active or chronic liver disease 1
• Caution when combining with tricyclic antidepressants or selective serotonin reuptake inhibitors 5
• Avoid combination with tamoxifen due to reduced efficacy of tamoxifen 5

Conclusion

While terbinafine has several well-documented side effects, hyponatremia is not among them based on current evidence. The medication is primarily cleared by the kidney, and its clearance is decreased in patients with severe kidney disease 1, but this has not been linked to electrolyte disturbances such as hyponatremia in the available literature.