Generic Name: verapamil (oral/injection) (ver AP a mil)
Brand Names: Calan, Isoptin SR, Verelan, Isoptin, Calan SR, Isoptin I.V., Covera-HS, Verelan PM
Medically reviewed by Sanjai Sinha, MD Last updated on Jan 20, 2019.
What is verapamil?
Verapamil is a calcium channel blocker. It works by relaxing the muscles of your heart and blood vessels.
Verapamil injection is used to rapidly or temporarily restore normal heartbeats in people with certain heart rhythm disorders.
You should not use verapamil if you have a serious heart condition such as "sick sinus syndrome" or "AV block" (unless you have a pacemaker), severe heart failure, Wolff-Parkinson-White, Lown-Ganong-Levine syndrome, or slow heartbeats that have caused you to faint.
Before taking this medicine
You should not use verapamil if you are allergic to it, or if you have a serious heart condition such as:
"sick sinus syndrome" or "AV block" (unless you have a pacemaker);
severe heart failure;
slow heartbeats that have caused you to faint; or
certain heart rhythm disorders (Wolff-Parkinson-White, Lown-Ganong-Levine syndrome).
To make sure verapamil is safe for you, tell your doctor if you have:
congestive heart failure;
liver disease; or
It is not known whether verapamil will harm an unborn baby. Tell your doctor if you are pregnant or plan to become pregnant.
You should not breast-feed while using this medicine.
How should I use verapamil?
Verapamil injection is given as an infusion into a vein, usually in an emergency situation. A healthcare provider will give you this injection. Your heart rate will be constantly monitored to help determine when your heartbeats have returned to normal.
Oral verapamil is taken by mouth. Follow all directions on your prescription label. Your doctor may occasionally change your dose. Do not use this medicine in larger or smaller amounts or for longer than recommended.
Swallow a capsule or tablet whole and do not crush, chew, break, or open it.
Your blood pressure will need to be checked often. Your liver function may also need to be checked.
If you need surgery, tell the surgeon ahead of time that you take verapamil.
If you have high blood pressure, keep using this medicine even if you feel well. High blood pressure often has no symptoms. You may need to use blood pressure medicine for the rest of your life.
Store at room temperature away from moisture, heat, and light.
What happens if I miss a dose?
Take the missed dose as soon as you remember. Skip the missed dose if it is almost time for your next scheduled dose. Do not take extra medicine to make up the missed dose.
What happens if I overdose?
Seek emergency medical attention or call the Poison Help line at 1-800-222-1222. An overdose of verapamil can be fatal.
What should I avoid while taking verapamil?
Drinking alcohol with verapamil can cause side effects.
Avoid getting up too fast from a sitting or lying position, or you may feel dizzy. Avoid driving or hazardous activity until you know how this medicine will affect you. Your reactions could be impaired.
Grapefruit may interact with verapamil and lead to unwanted side effects. Avoid the use of grapefruit products.
Verapamil side effects
Get emergency medical help if you have signs of an allergic reaction: hives; difficult breathing; swelling of your face, lips, tongue, or throat.
Call your doctor at once if you have:
chest pain, fast or slow heart rate;
a light-headed feeling, like you might pass out;
shortness of breath (even with mild exertion), swelling, rapid weight gain;
fever, upper stomach pain, not feeling well; or
lung problems--anxiety, sweating, pale skin, wheezing, gasping for breath, cough with foamy mucus.
Common side effects may include:
This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.
What other drugs will affect verapamil?
Many drugs can interact with verapamil. Some drugs can raise or lower your blood levels of verapamil, which may cause side effects or make it less effective. Not all possible interactions are listed here. Tell your doctor about all your current medicines and any you start or stop using, especially:
aspirin, imatinib, lithium, nefazodone, St. John's wort;
all other heart or blood pressure medicines, especially clonidine, digoxin, flecainide, ivabradine, nicardipine, or quinidine;
an antibiotic - clarithromycin, telithromycin;
antifungal medicine - itraconazole, ketoconazole, posaconazole, voriconazole;
antiviral medicine to treat hepatitis or HIV/AIDS - atazanavir, boceprevir, cobicistat, delavirdine, efavirenz, fosamprenavir, indinavir, nelfinavir, ritonavir, saquinavir;
a beta blocker - atenolol, carvedilol, labetalol, metoprolol, nadolol, nebivolol, propranolol, sotalol, and others;
cholesterol lowering medicine - atorvastatin, fluvastatin, lovastatin, pitavastatin, pravastatin, rosuvastatin, simvastatin;
drugs to treat high blood pressure or a prostate disorder - alfuzosin, doxazosin, prazosin, terazosin, silodosin, tamsulosin;
seizure medicine - carbamazepine, phenobarbital, phenytoin; or
tuberculosis medicine - isoniazid, rifampin.
This list is not complete and many other drugs can interact with verapamil. This includes prescription and over-the-counter medicines, vitamins, and herbal products. Give a list of all your medicines to any healthcare provider who treats you.
Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use this medication only for the indication prescribed.
Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.
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More about verapamil
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- Drug class: calcium channel blocking agents
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- Verapamil Injection
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- Verapamil Intravenous (Advanced Reading)