Before taking sotalol, tell your doctor or pharmacist if you are allergic to it; or if you have any other allergies. This product may contain inactive ingredients, which can cause allergic reactions or other problems. Talk to your pharmacist for more details. Before using this medication, tell your doctor or pharmacist your medical history, especially of: certain heart rhythm problems (such as a slow heartbeat, sick sinus syndrome, second- or third-degree atrioventricular block unless you have a heart pacemaker), kidney problems, heart failure, breathing problems (such as asthma, chronic bronchitis, emphysema), very recent heart attack (within 2 weeks), overactive thyroid disease (hyperthyroidism), serious allergic reactions needing treatment with epinephrine. Sotalol may cause a condition that affects the heart rhythm (QT prolongation in the EKG). QT prolongation can rarely cause serious (rarely fatal) fast/irregular heartbeat and other symptoms (such as severe dizziness, fainting) that need medical attention right away. The risk of QT prolongation may be increased if you have certain medical conditions or are taking other drugs that may cause QT prolongation. Before using sotalol, tell your doctor or pharmacist of all the drugs you take and if you have any of the following conditions: certain heart problems (QT prolongation in the EKG, history of torsade de pointes), family history of certain heart problems (QT prolongation in the EKG, sudden cardiac death). Low levels of potassium or magnesium in the blood may also increase your risk of QT prolongation. This risk may increase if you use certain drugs (such as diuretics/"water pills"), if you are unable to eat or drink fluids as you normally would, or if you have conditions such as severe/prolonged sweating, diarrhea, or vomiting. Talk to your doctor about using sotalol safely. If you have diabetes, this product may mask the fast/pounding heartbeat you would usually feel when your blood sugar falls too low (hypoglycemia). Other symptoms of low blood sugar, such as dizziness and sweating, are unaffected by this drug. This product may also make it harder to control your blood sugar. Check your blood sugar regularly as directed and share the results with your doctor. Tell your doctor right away if you have symptoms of high blood sugar such as increased thirst/urination. Your doctor may need to adjust your diabetes medication, exercise program, or diet. Before having surgery, tell your doctor or dentist that you are taking this medication. This drug may make you dizzy. Alcohol or marijuana (cannabis) can make you more dizzy. Do not drive, use machinery, or do anything that needs alertness until you can do it safely. Limit alcoholic beverages. Talk to your doctor if you are using marijuana (cannabis). Older adults may be more sensitive to the side effects of this drug, especially dizziness, tiredness, and QT prolongation (see above). During pregnancy, this medication should be used only when clearly needed. It may harm an unborn baby. Discuss the risks and benefits with your doctor. This medication passes into breast milk and may have undesirable effects on a nursing infant. Discuss the risks and benefits with your doctor before breast-feeding.