Side Effects of Terbinafine (Lamisil)
Terbinafine commonly causes gastrointestinal side effects (49% of cases) such as nausea, diarrhea, dyspepsia, abdominal pain, and flatulence, as well as dermatological reactions (23%) including rash, pruritus, and urticaria. 1, 2
Common Side Effects
Gastrointestinal effects:
- Nausea
- Diarrhea
- Dyspepsia (indigestion)
- Abdominal pain
- Flatulence
Dermatological effects:
- Rash
- Pruritus (itching)
- Urticaria (hives)
- Eczema
Sensory disturbances:
- Taste disturbance or loss of taste (may be prolonged or permanent)
- Smell disturbance or loss of smell (may be prolonged or permanent)
Serious Side Effects
Hepatotoxicity
- Liver enzyme abnormalities are common
- Rare cases of serious hepatic toxicity have been reported 1
- Not recommended in patients with active or chronic liver disease
- Liver failure requiring transplantation or resulting in death has occurred 2
- Pretreatment serum transaminase testing is recommended
Severe Cutaneous Adverse Reactions
- Stevens-Johnson syndrome
- Toxic epidermal necrolysis
- Erythema multiforme
- Exfoliative dermatitis
- Bullous dermatitis
- Drug reaction with eosinophilia and systemic symptoms (DRESS) 2
Neuropsychiatric Effects
- Depressive symptoms 2
- Changes in mood
- Loss of energy or interest in daily activities
Rare but Serious Adverse Events
- Severe neutropenia (discontinue if neutrophil count ≤1,000 cells/mm³) 2
- Hypersensitivity syndrome reaction (cutaneous eruption, fever, lymphadenopathy, hepatic dysfunction) 3
- Rhabdomyolysis with acute kidney injury (characterized by muscle pain, weakness, dark urine) 4
Drug Interactions
Terbinafine inhibits CYP450 2D6 isozyme and may interact with:
- Antidepressants (particularly tricyclics)
- Antipsychotics
- Cardiovascular medications
- Desipramine
- Caffeine
- Cyclosporine
- Fluconazole
- Rifampin
- Cimetidine 2, 5
The combination of terbinafine with tamoxifen should be avoided as it can reduce tamoxifen's efficacy 5.
Special Populations
Pregnancy and Breastfeeding
- Contraindicated in pregnancy 1
- Manufacturers caution against men fathering a child for 6 months after therapy 1
- Passes into breast milk and may harm babies 2
Patients with Comorbidities
- Not recommended in patients with active or chronic liver disease 1
- Terbinafine clearance is decreased in severe liver or kidney disease 1
- Generally well-tolerated in older and multimorbid patients due to fewer drug interactions compared to azole antifungals 5
Monitoring Recommendations
- Obtain pretreatment serum transaminases 2
- Discontinue terbinafine if:
- Signs of liver injury develop
- Taste or smell disturbance occurs
- Depressive symptoms emerge
- Severe skin reactions appear
- Neutropenia develops
The overall incidence of serious adverse events with terbinafine is low (0.04% in postmarketing surveillance) 1, making it generally well-tolerated for most patients when proper monitoring is implemented.