Verapamil: what it treats, how to take it, side effects
Last updated September 3, 2026.
Verapamil is a calcium channel blocker that relaxes blood vessels and slows the heart's electrical activity. It covers three jobs at once: high blood pressure, angina, and irregular heartbeats. Its most famous quirk is the constipation - and the grapefruit.
What does it treat?
High blood pressure and angina (chest pain) across all its forms; the immediate-release tablets also prevent and treat irregular heartbeats, alone or with other medications. It controls these conditions; it does not cure them.
How do you take it?
The regular tablet is taken three to four times a day; the extended-release tablets and capsules once or twice a day, same times every day. Timing varies by product - some go in the morning, others at bedtime - so ask your doctor what time is right for yours. Swallow extended-release forms whole; ask your pharmacist whether your tablets may be split, because that varies by product too. If you cannot swallow the capsule, open it, sprinkle the entire contents on a spoonful of cool, soft applesauce, swallow without chewing, and drink a glass of cool water. Your doctor starts low and increases gradually. Keep taking it even when you feel well, and never stop without your doctor. Missed dose: take it when you remember unless the next one is close; never double up.
Side effects to know
- Common: constipation (the signature one - ask about fiber and fluids if it shows up), heartburn, dizziness or lightheadedness, and headache.
- Serious: swelling of the hands, feet, ankles, or lower legs; trouble breathing or swallowing; slow heartbeat; fainting; blurred vision; rash; and the liver-injury cluster - nausea, extreme tiredness, unusual bleeding or bruising, lack of energy, loss of appetite, upper right stomach pain, yellowing skin or eyes, flu-like symptoms, and fever. Call your doctor immediately or get emergency care.
Who should not take it?
Flag heart failure, a slow heart rate or heart-rhythm problems, low blood pressure, and liver or kidney disease. Grapefruit is the specific one here: MedlinePlus says talk to your doctor about eating grapefruit or drinking grapefruit juice while taking verapamil, because it raises drug levels. Alcohol is the other: verapamil may make the effects of alcohol more severe and longer-lasting - talk to your doctor about safe use. It can make you dizzy - no driving until you know it. Pregnancy and breastfeeding need a direct call.
When is it an emergency?
Call 911 for fainting, a very slow heartbeat, or trouble breathing or swallowing. Yellowing skin or eyes with upper right stomach pain and fever mean immediate care. 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 can't I have grapefruit with verapamil?
Grapefruit blocks the enzyme that clears verapamil, so levels climb higher than the dose intended - more blood-pressure drop, slower heart rate, more side effects. MedlinePlus says talk to your doctor about eating grapefruit or drinking grapefruit juice while taking it. The safe default is to drop grapefruit from the routine entirely.
Why does verapamil cause constipation?
The same calcium-channel relaxing it does in blood vessels happens in the gut, slowing things down. Constipation is the first item on MedlinePlus's common side effect list for verapamil - it is the drug's signature. Fiber, fluids, and movement are the first-line fixes; persistent trouble is a doctor conversation.
Can I drink alcohol while taking verapamil?
MedlinePlus says talk to your doctor about the safe use of alcohol during treatment - verapamil may cause the effects of alcohol to be more severe and longer-lasting. You will feel one drink like more than one. That changes the math on any amount.
How is verapamil different from amlodipine?
Both are calcium channel blockers, but verapamil also slows the heart's electrical activity - which is why it treats irregular heartbeats in addition to blood pressure and angina, and why a slow heartbeat and constipation are its signature effects where amlodipine's is ankle swelling.
Why does my verapamil say take it at bedtime?
Because the products differ. MedlinePlus notes certain verapamil products should be taken in the morning and others at bedtime, and says to ask your doctor what the best time is for yours. The extended-release versions are engineered for specific release patterns - follow your label, not a general rule.
What happens if I miss a dose of verapamil?
Take it as soon as you remember, unless it is almost time for the next one - then skip it and never double up. Doubling a medication that slows the heart is how a slow pulse becomes a faint.