It is used to treat tremors, angina (chest pain), hypertension (high blood pressure), heart rhythm disorders, and other heart or circulatory conditions. It is also used to treat or prevent heart attacks, and to reduce the severity and frequency of migraine headaches.

slow or uneven heartbeats, a light-headed feeling, like you might pass out, wheezing or trouble breathing

It is contraindicated in patients with known hypersensitivity to the drug