Sotalol: what it treats, how to take it, side effects
Last updated September 3, 2026.
Sotalol is an antiarrhythmic - it acts on the heart muscle to improve the heart's rhythm. You may know it as Betapace or Betapace AF. It is a rhythm drug with a serious start: the first three days happen in a facility where your heart can be monitored, because the drug itself can provoke a dangerous rhythm in that window.
What does it treat?
Serious, life-threatening ventricular arrhythmias, and maintaining normal rhythm in people who have had symptomatic atrial fibrillation or atrial flutter. It controls the rhythm; it does not cure the condition.
How do you take it?
Tablets two or three times a day, or the oral solution once a day in adults (three times a day in children) - consistently either always with food or always without, because food changes absorption. Your doctor starts low and increases gradually. Never stop suddenly: stopping sotalol abruptly can trigger serious heart problems - angina or heart attack - so any exit is a gradual taper over 1 to 2 weeks under your doctor's eye, usually with physical activity limited. Missed dose: take it when you remember unless the next one is close; never double up.
Side effects to know
- Common: dizziness, lightheadedness, weakness, excessive tiredness, headache, diarrhea, nausea, and vomiting.
- Serious - call your doctor immediately: fast, pounding, or irregular heartbeat, fainting, or loss of consciousness - the QT-prolongation pattern the monitoring exists to catch; plus shortness of breath or wheezing, swelling of the feet and lower legs, unusual weight gain, chest pain, and dizziness.
Who should not take it?
Anyone with long QT syndrome, personal or family - and flag low potassium, slow or irregular heartbeat, heart failure, and kidney disease, all of which raise the rhythm risk; your doctor may rule the drug out. The monitoring is ongoing, not just at the start: heart-rhythm checks, kidney function, and potassium levels on schedule. Many other drugs prolong QT - the full medication list gets screened. If you become pregnant, call your doctor.
When is it an emergency?
Fainting, loss of consciousness, or a racing, pounding, irregular heartbeat is a 911 call. For an overdose, call Poison Control at 1-800-222-1222. Pymander's escalation routing is built and tested specifically for this class of decision; see the safety architecture working paper.
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Common questions
Why did I have to start sotalol in a facility?
Because of QT prolongation - an irregular heart rhythm the drug itself can provoke, which can lead to fainting, seizures, or sudden death. The risk concentrates in the first days, so MedlinePlus states you spend the first three days where your heart can be monitored. It is not a sign your case is dire; it is the standard launch protocol for this drug.
Why can't I just stop taking sotalol?
Abruptly stopping can rebound into serious heart problems - angina or heart attack. MedlinePlus: do not stop without talking to your doctor; the exit is a gradual dose decrease over 1 to 2 weeks with close watching, and you will probably be told to limit physical activity during the taper. The "continue even if you feel well" instruction is structural, not boilerplate.
Why does my doctor keep checking my potassium and kidneys?
Both steer the rhythm risk: low potassium prolongs QT further, and the kidneys clear sotalol - slow kidneys let it accumulate into the danger zone. So the labs are scheduled, not optional: rhythm checks, kidney function, potassium. Between draws, the call-immediately set is short and memorable: fast, pounding, or irregular heartbeat; fainting; loss of consciousness.
Why do I take it the same way with food every time?
Food changes how much sotalol you absorb - always-with-food and always-without-food behave like different doses. MedlinePlus says take it consistently one way or the other. Pick the pattern that matches your life and lock it in; the prescriber calibrated your dose against whichever you choose.
Why did my doctor screen my whole medication list?
Many drugs prolong QT - certain antibiotics, antifungals, antidepressants, other antiarrhythmics - and stacking them on sotalol stacks the rhythm risk. The screening happens before the first dose and recurs with every new prescription. This is the medication where "just an antibiotic" is never just an antibiotic - every prescriber needs to know sotalol is aboard.
What happens if I miss a dose of sotalol?
Take it as soon as you remember, unless it is almost time for the next one - then skip it and never double up. Doubling an antiarrhythmic is precisely how the rhythm risk gets provoked. If you miss doses often, tell your cardiologist - adherence is part of the safety picture for this drug.