Verapamil (Calan) – Side Effects, Interactions, Uses, Dosage, Warnings

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 is Verapamil (Calan) used for?

  • Hypertension
  • Pre-eclampsia/Eclampsia
  • Supraventricular Tachycardia
  • Angina Pectoris
  • Heart Block
  • Heart Disease
  • Ventricular Arrhythmia
  • Cardiovascular Disease
  • Ischemic Heart Disease
  • Sinus Node Dysfunction
  • Arrhythmias
  • Preexcitation Syndrome
  • Hypertensive Congestive Heart Failure
  • Hypertensive Heart (w/ CHF) and Renal Disease
  • Hypertensive Heart (w/o CHF) and Renal Disease
  • Hypertensive Renal Disease
  • Hypertensive Retinopathy
  • Renovascular Hypertension
  • Hypertensive Encephalopathy
  • Hypertensive Heart Disease
  • Tachyarrhythmia
  • Long QT Syndrome
  • Short QT Syndrome
  • Prinzmetal's Angina


What is the most important information I should know about Verapamil (Calan)?

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," Wolff-Parkinson-White syndrome, 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).

Tell your doctor if you have ever had:

  • congestive heart failure;
  • kidney disease;
  • liver disease; or
  • a nerve-muscle disorder such as myasthenia gravis or muscular dystrophy.

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 breastfeed while using verapamil.

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

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Side Effects

What are the side effects of Verapamil (Calan)?

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:

  • nausea, constipation;
  • 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.

Pregnancy & Breastfeeding

Can I take Verapamil (Calan) if I’m pregnant or breastfeeding?

Risk cannot be ruled out
Based on FDA pregnancy categories

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 breastfeed while using verapamil.


What drugs and food should I avoid while taking Verapamil (Calan)?

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.

Dosage Guidelines & Tips

How to take Verapamil (Calan)?

Use Verapamil (Calan) exactly as directed on the label, or as prescribed by your doctor. Do not use in larger or smaller amounts or for longer than recommended.

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 should I do if I missed a dose of Verapamil (Calan)?

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.

Overdose Signs

What happens if I overdose on Verapamil (Calan)?

If you think you or someone else may have overdosed on: Verapamil (Calan),  call your doctor or the Poison Control center

(800) 222-1222

If someone collapses or isn't breathing after taking Verapamil (Calan), call 911




Color: peach

Shape: oval

Imprint: 80, CALAN


Color: brown

Shape: oval

Form: film coated

Imprint: CALAN 120


Color: green

Shape: capsule

Form: film coated

Imprint: CALAN, SR 240

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