Sotalol, sold under the brand name Betapace among others, is a medication used to treat and prevent abnormal heart rhythms. It is only recommended in those with significant abnormal heart rhythms due to potentially serious side effects. Evidence does not support a decreased risk of death with long term use. It is taken by mouth or injection into a vein. Common side effects include a slow heart rate, chest pain, low blood pressure, feeling tired, dizziness, shortness of breath, problems seeing, vomiting, and swelling. Other serious side effects may include QT prolongation, heart failure, or bronchospasm. Sotalol is a non-selective beta-adrenergic receptor blocker which has both class II and class III antiarrhythmic properties. Sotalol was first described in 1964 and came into medical use in 1974. It is available as a generic medication. In 2020, it was the 296th most commonly prescribed medication in the United States, with more than 1million prescriptions. Medical uses According to the U.S. Food and Drug Administration (FDA), sotalol can be validly used to maintain a normal heart rhythm in people with life-threatening ventricular arrhythmias (e.g., ventricular tachycardia), or very symptomatic atrial fibrillation or flutter. Due to the risk of serious side effects, the FDA states that sotalol should generally be reserved for people whose ventricular arrhythmias are life-threatening, or whose fibrillation/flutter cannot be resolved using the Valsalva maneuver or another simple method. Sotalol has shown some potential efficacy against symptoms of essential tremor due to its binding to the Beta-2 adrenergic receptor but this remains an off-label use. Contraindications According to the FDA, sotalol should not be used in people with a waking heart rate lower than 50 beats per minute. It should not be used in people with sick sinus syndrome, long QT syndrome, cardiogenic shock, uncontrolled heart failure, asthma or a related bronchospastic condition, or people with serum potassium below 4 meq/L. It should only be used in people with a second and third degree AV block if a functioning pacemaker is present. Since sotalol is removed from the body through the kidneys, it should not be used in people with a creatinine clearance rate below 40 mL/min. It is also excreted in breast milk, so mothers should not breastfeed while taking sotalol. Since sotalol prolongs the QT interval, the FDA recommends against using it in conjunction with other medications that prolong the QT interval. Studies have found serious side effects to