Can Steroids Be Taken Concurrently with Terbinafine?
Yes, a 45-year-old woman taking terbinafine (Lamisil) for onychomycosis can safely take corticosteroids for unrelated wrist inflammation, as there are no clinically significant drug interactions between these medications.
Rationale for Safety
Terbinafine has minimal drug-drug interactions compared to azole antifungals (itraconazole, fluconazole), making it one of the safest systemic antifungals for patients on multiple medications 1, 2.
The only potentially significant interactions with terbinafine involve drugs metabolized by cytochrome P450 2D6 (certain antidepressants, beta-blockers, antiarrhythmics), not corticosteroids 1, 3.
Unlike itraconazole, which has extensive drug interactions requiring caution with many medications including statins, terbinafine's interaction profile is remarkably clean 4.
Clinical Evidence Supporting Concurrent Use
A large safety study in elderly patients (≥65 years) demonstrated that 64% took antihypertensive medications, 25% took antidiabetics, and 47% took antilipemic medications concurrently with terbinafine without any clinical signs of drug interactions 5.
The treatment-emergent adverse event rate was only 28% in elderly patients on multiple medications, with most events being mild (73.7%) to moderate (23.7%) and unrelated to terbinafine 5.
Important Monitoring Considerations
While steroids can be safely prescribed, continue standard terbinafine monitoring:
Baseline liver function tests and complete blood count were obtained before starting terbinafine 1, 3, 6.
Monitor liver function tests if the patient has a history of hepatitis, heavy alcohol use, or develops symptoms suggestive of hepatotoxicity 1, 3.
The most common adverse effects of terbinafine are gastrointestinal complaints (nausea, diarrhea), headache, and taste disturbance—none of which are exacerbated by corticosteroids 1, 3, 2.
Practical Prescribing Guidance
Prescribe the corticosteroid as clinically indicated for wrist inflammation without dose adjustment of terbinafine 1.
Continue terbinafine 250 mg daily for the full treatment duration: 6 weeks for fingernail onychomycosis or 12-16 weeks for toenail onychomycosis 1, 3, 6.
Counsel the patient that neither medication requires timing adjustments relative to the other, as terbinafine can be taken with or without food 3.
Key Clinical Caveat
The primary concern with terbinafine is hepatotoxicity, not drug interactions. Active or chronic liver disease is an absolute contraindication to terbinafine 1, 3, 6. If the patient develops signs of liver dysfunction (jaundice, dark urine, persistent nausea, abdominal pain), discontinue terbinafine immediately and check liver function tests 1.