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Verapamil (oral/injection)

Generic name: verapamil (oral/injection) [ ver-AP-a-mil ]
Brand names: Calan, Isoptin SR, Verelan, Isoptin, Calan SR, ... show all 8 brands
Dosage forms: intravenous solution (2.5 mg/mL), oral capsule, extended release (100 mg/24 hours; 120 mg/24 hours; 180 mg/24 hours; 200 mg/24 hours; 240 mg/24 hours; 300 mg/24 hours; 360 mg/24 hours), ... show all 4 dosage forms
Drug classes: Calcium channel blocking agents, Group IV antiarrhythmics

Medically reviewed by on Nov 8, 2022. Written by Cerner Multum.

What is verapamil?

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.


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), or Wolff-Parkinson-White, Lown-Ganong-Levine syndrome.

Before taking this medicine

You should not use verapamil if you are allergic to it, or if you have:

  • "sick sinus syndrome" or "AV block" (unless you have a pacemaker);

  • very low blood pressure; or

  • if your heart cannot pump blood properly.

You may not be able to use verapamil if you have:

Tell your doctor if you have ever had:

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 breastfeed while using verapamil.

Verapamil oral is not approved for use by anyone younger than 18 years old.

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.

Do not use the medicine if it looks cloudy or has particles in it. Call your pharmacist for new medicine.

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?

Verapamil injection: Call your doctor for instructions if you miss a dose.

Verapamil oral: 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.

Verapamil may cause serious side effects. 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 of verapamil 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?

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.

Further information

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.