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verapamil (oral/injection) (Calan, Calan SR, Isoptin)

Brand Names: Calan, Calan SR, Isoptin, Isoptin SR, Verelan, Verelan PM

Generic Name: verapamil (oral)

What is verapamil?

Verapamil is a calcium channel blocker. It works by relaxing the muscles of your heart and blood vessels.

Verapamil is used to treat hypertension (high blood pressure), angina (chest pain), and certain heart rhythm disorders.

Verapamil injection is used to rapidly or temporarily restore normal heartbeats in people with certain heart rhythm disorders.

Verapamil may also be used for purposes not listed in this medication guide.

What are the possible side effects of verapamil?

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 is the most important information I should know about verapamil?

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.

What should I discuss with my healthcare provider before using verapamil?

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).

Tell your doctor if you have ever had:

It is not known whether this medicine 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.

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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 this medicine 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.

What other drugs will affect verapamil?

If you also take disopyramide, avoid taking it within 48 hours before or 24 hours after you take verapamil.

Sometimes it is not safe to use certain medications at the same time. Some drugs can affect your blood levels of other drugs you take, which may increase side effects or make the medications less effective.

Many drugs can affect verapamil. This includes prescription and over-the-counter medicines, vitamins, and herbal products. Not all possible interactions are listed here. Tell your doctor about all your current medicines and any medicine you start or stop using.

Where can I get more information?

Your pharmacist can provide more information about verapamil.


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.
Every effort has been made to ensure that the information provided by Cerner Multum, Inc. ('Multum') is accurate, up-to-date, and complete, but no guarantee is made to that effect. Drug information contained herein may be time sensitive. Multum information has been compiled for use by healthcare practitioners and consumers in the United States and therefore Multum does not warrant that uses outside of the United States are appropriate, unless specifically indicated otherwise. Multum's drug information does not endorse drugs, diagnose patients or recommend therapy. Multum's drug information is an informational resource designed to assist licensed healthcare practitioners in caring for their patients and/or to serve consumers viewing this service as a supplement to, and not a substitute for, the expertise, skill, knowledge and judgment of healthcare practitioners. The absence of a warning for a given drug or drug combination in no way should be construed to indicate that the drug or drug combination is safe, effective or appropriate for any given patient. Multum does not assume any responsibility for any aspect of healthcare administered with the aid of information Multum provides. The information contained herein is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. If you have questions about the drugs you are taking, check with your doctor, nurse or pharmacist.

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Reviewed on 7/23/2019

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