Generic name: verapamil (oral/injection) [ ver-AP-a-mil ]
Brand names: Calan, Calan SR, Isoptin SR, Verelan, Verelan PM, ... show all 8 brands Isoptin, Isoptin I.V., Covera-HS
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 oral tablet (120 mg; 40 mg; 80 mg), oral tablet, extended release (120 mg/12 hours; 180 mg/12 hours; 240 mg/12 hours)
Drug classes: Calcium channel blocking agents, Group IV antiarrhythmics

Medically reviewed by Melisa Puckey, BPharm. Last updated on Mar 1, 2024.

What is verapamil?

Verapamil belongs to a class of medications called calcium-channel blockers. It works by relaxing the muscles of your heart and blood vessels so the heart does not have to pump as hard. Verapamil also increases the supply of blood and oxygen to the heart and slows electrical activity in the heart to control the heart rate.

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

The immediate-release tablets are also used alone or with other medications to prevent and treat irregular heartbeats.

Verapamil injection is used in adults and children to rapidly or temporarily restore normal heart rate in people with certain heart rhythm disorders.

High blood pressure is a common condition and when not treated, can cause damage to the brain, heart, blood vessels, kidneys and other parts of the body. Damage to these organs may cause heart disease, a heart attack, heart failure, stroke, kidney failure, loss of vision, and other problems. In addition to taking medication, making lifestyle changes will also help to control your blood pressure. These changes include eating a diet that is low in fat and salt, maintaining a healthy weight, exercising at least 30 minutes most days, not smoking, and using alcohol in moderation.

Warnings

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.

Tell your doctor what herbal products you are taking, especially St. John's wort.

Tell your doctor if you have or have ever had narrowing or blockage of your digestive system or any other condition that causes food to move through your digestive system more slowly; heart failure; heart, liver, or kidney disease; muscular dystrophy (inherited disease that causes gradual weakening of muscles); or myasthenia gravis (condition that causes certain muscles to weaken).

Talk to your doctor about the safe use of alcoholic beverages during your treatment. Verapamil may cause the effects of alcohol to be more severe and longer-lasting.

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:

• severe congestive heart failure;

• certain heart rhythm disorders (such as 'Afib' or atrial flutter with Wolff-Parkinson-White syndrome or Lown-Ganong-Levine syndrome);

• a heart condition that causes you to have very rapid heartbeats; or

• if you are receiving an intravenous beta-blocker (such as atenolol, metoprolol, or propranolol).

To make sure verapamil is safe for you, tell your doctor if you have ever had:

• low blood pressure;

• abnormal thickening of the heart muscle;

• certain types of brain tumors;

• congestive heart failure;

• a nerve-muscle disorder such as myasthenia gravis or muscular dystrophy; or

• kidney or liver disease.

It is not known if verapamil will harm an unborn baby. Tell your doctor if you are pregnant or plan to become pregnant.

Do not breastfeed.

How should I use verapamil?

Use verapamil exactly as prescribed by your doctor. Follow all directions on your prescription label and read all medication guides or instruction sheets. Your doctor may occasionally change your dose.

Verapamil injection is given into a vein by a healthcare provider. Your heart rate will be constantly monitored using an electrocardiogram or ECG (sometimes called an EKG). Your blood pressure and other vital signs will also be watched closely.

Verapamil oral is taken by mouth. Your pharmacist can provide more information about how to take the tablets or capsules.

Your dose needs may change if you switch to a different brand, strength, or form of this medicine.

Some forms of verapamil oral cannot be crushed or chewed, and some forms can be opened and mixed with applesauce. Ask your pharmacist how to take this medicine.

Your blood pressure and liver function will need to be checked often.

If you have high blood pressure, keep using this medicine even if you feel well. High blood pressure often has no symptoms.

Store at room temperature away from moisture, heat, and light.

What happens if I miss a dose?

Verapamil injection is used when needed and does not have a daily dose. Call your doctor if the medicine is not effective.

Take verapamil oral as soon as you can, but skip the missed dose if it is almost time for your next dose. Do not use two doses at one time.

What happens if I overdose?

Seek emergency medical attention or call the Poison Help line at 1-800-222-1222. An overdose can be fatal.

Overdose symptoms may include low blood pressure, slow heart rate, chest pain, shortness of breath, tiredness, high blood sugar, confusion, severe dizziness or fainting.

What should I avoid while using verapamil?

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 cause side effects. Avoid consuming grapefruit products.

Drinking alcohol with this medicine can cause side effects.

Verapamil side effects

Get emergency medical help if you have signs of an allergic reaction to verapamil: 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, slow, or uneven heart rate;

• a light-headed feeling, like you might pass out;

• heart problems - swelling, rapid weight gain, feeling short of breath;

• liver problems - loss of appetite, stomach pain (upper right side), tiredness, itching, dark urine, clay-colored stools, jaundice (yellowing of the skin or eyes); or

• fluid build-up in or around the lungs - pain when you breathe, feeling short of breath while lying down, wheezing, gasping for breath, cough with foamy mucus, cold, clammy skin, anxiety, rapid heartbeats.

Common verapamil side effects may include:

• nausea, constipation;

• infections, flu symptoms;

• swelling in lower legs or hands;

• headache, dizziness; or

• low blood pressure.

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 medicines at the same time. Some drugs can affect your blood levels of other drugs you use, which may increase side effects or make the medicines less effective.

Many drugs can interact with 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 other medicines you use.

Further information

Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use verapamil 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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