This medicine is used to irregular beating of the heart.Store at controlled room temperature (between 59 to 86 degrees F) in a tight, light-resistant container. Keep all medicines out of the reach of children and pets. Protect from excessive heat and moisture.How much medicine you take and how often you take it depends on many factors, including the condition being treated and the age and weight of the patient. If you have any questions about the amount and/or frequency of the medicine you are taking, talk with your health care provider. This medicine should only be given by a health care provider who is experienced in the use of this medicine. If severe diarrhea, stomach pain/cramps, or bloody stools occur, contact your health care provider at once. This could be a symptom of a serious side effect requiring instant medical attention. Do not treat diarrhea without talking with your health care provider. Patients with previous medical conditions should talk with their health care provider before taking this medicine. Do not take any other over-the-counter or prescription medicines without talking with your health care provider.Do not take this medicine if you are allergic to any ingredient in this medicine or to similar medicationsBefore using this medicine, tell your health care provider about any of the following: if you are pregnant, planning to become pregnant, or breastfeeding if you are taking any prescription medicine, nonprescription medicine, herbal preparation, or dietary supplement if you have any other medical condition like liver, kidney, lung or heart disease.This medicine has several potentially fatal toxicities, the most important of which is pulmonary toxicity (hypersensitivity pneumonitis or interstitial/alveolar pneumonitis) and liver toxicity. This medicine should be used with extreme cautionMost severe: Optic neuropathy and/or optic neuritis, permanent blindness, papilledema, corneal degeneration, photosensitivity, eye discomfort, scotoma, lens opacities and macular degeneration.Most common: Nausea, vomiting, diarrhea, stomach pain.Other: Malaise, fatigue, tremor/abnormal involuntary movements, lack of coordination, abnormal gait/ataxia, dizziness, paresthesias, constipation, anorexia, visual disturbances, abnormal liver-function tests, pulmonary inflammation or fibrosis.