Clinical Effect of Caffeine Consumption in Patients Taking Oral Terbinafine

Terbinafine is a common oral medication used for moderate to severe nail onychomycosis. On the terbinafine package insert, it states that terbinafine can reduce clearance of caffeine by 19%. However, the clinical effects of this finding in patients have yet to really be studied. Decreased clearance of caffeine can physically present with measurable signs such as an increased blood pressure or increased heart rate, as well as less measurable symptoms of GI upset, irritability, headache, insomnia. As a result, dermatologists do not always know how to counsel patients taking terbinafine on their caffeine intake. Hence, recommendations vary as no studies have been done on whether caffeine consumption while taking terbinafine is associated with clinical outcomes, such as measurable changes in blood pressure or heart rate.

This will be a preliminary single-blind randomized control clinical study. Patients being started on oral terbinafine by video visit will be approached for enrollment in the study. Patients will be provided with the baseline survey, to assess demographic information, BMI, and daily caffeine intake. Patients with a history of hypertension and anxiety will not be enrolled per the exclusion criteria. If the patient's blood pressure or heart rate are abnormal, they will be removed from the study

We hypothesize that there would be significant changes in blood pressure or heart rate in patients consuming caffeine while taking terbinafine.

Inclusion criteria

• Patient of any gender at least 18 years of age
• Diagnosed with onychomycosis
• Planning to start oral terbinafine

Exclusion criteria

• Pregnant or breastfeeding
• Any history of anxiety or hypertension
• Any patient with an inability to give consent