In extremely rare cases, the loss or impairment of taste is permanent 
Skin problems: Rashes, hives (urticaria), skin irritation, itching, jaundice, Stevens–Johnson syndrome
Other side effects: Fatigue, increased heart rate (tachycardia), hair loss (alopecia), decreased red blood cell count (anemia), muscle pain (myalgia), joint pain (arthralgia)In 2015 physicians reported that a patient with an MTHFR enzyme mutation (specifically the C677T variant) had developed an adverse reaction to Lamisil (headache, fatigue, and dizziness). Genetic testing revealed the MTHFR C677T mutation. It was noted that Lamisil interferes with the methylation cycle and that this can cause side effects in individuals with the MTHFR C677T mutation. Pharmacology
Like other allylamines, terbinafine inhibits ergosterol synthesis by inhibiting squalene epoxidase, an enzyme that catalyzes the conversion of squalene to lanosterol. In fungi, lanosterol is then converted to ergosterol; in humans, lanosterol becomes cholesterol. However, as fungi and animals diverged around 1.1 billion years ago - there is enough difference in this enzyme that terbinafine preferentially binds fungal squalene epoxidase, making it selective for inhibiting ergosterol production in fungi without significantly affecting cholesterol production in mammals. This is thought to fatally disrupt the fungal cell membrane. Terbinafine is highly lipophilic and tends to accumulate in hair, skin, nails, and fat cells. This accumulation results in therapeutic levels of terbinafine even after 80 days following one week treatment of 250 mg/day.
Trifascicular block is a problem with the electrical conduction of the heart, specifically the three fascicles of the bundle branches that carry electrical signals from the atrioventricular node to the ventricles. The three fascicles are one in the right bundle branch, and two in the left bundle branch the left anterior fascicle and the left posterior fascicle. A block at any of these levels can cause an abnormality to show on an electrocardiogram
The most literal meaning of trifascicular block is complete heart block: all three fascicles are blocked. A second, and clinically distinct, definition of trifascicular block is a circumstance in which right bundle branch block (RBBB) and left bundle branch block occur in the same patient, but at distinct points in time. For example, a patient that is found to have a RBBB one day and a LBBB another can be said to have "alternating bundle branch blocks". In this context, because all three fascicles show evidence of block at different points in time, the term trifascicular block is often used. Finally, the third meaning of trifascicular block refers to a specific finding on an electrocardiogram in which bifascicular block is observed in a patient with a prolonged PR interval (first degree AV block). The treatment of trifascicular block is highly dependent on which clinical entity (one of the three above) is being described. Diagnosis
An electrophysiology study of the conduction system can help discern the severity of conduction system disease.