Ask your doctor or pharmacist before using any other medicine, including over-the-counter medicines, vitamins, and herbal products.
Make sure your doctor knows if you are also taking diuretics (water pills), Tagamet®, rifampin (Rifadin®, Rifamate®), or drugs to treat heart rhythm problems.
Make sure your doctor knows about all cancer medicines you may be receiving, especially drugs like doxorubicin (Adriamycin®) or daunorubicin (Cerubidine®).
If you are pregnant or breastfeeding, talk to your doctor before taking this medicine.
Make sure your doctor knows if you have heart disease, especially heart rhythm problems. Also tell your doctor if you have low potassium or magnesium levels.