Verapamil: What is it? How does it work? Uses, Side Effects and Interactions

It is a prescription medication that is available as the brand name drugs Verelan PM (extended release) and Verelan (delayed release).

The oral extended-release capsule is also available as a generic medicine.

Generic drugs usually cost less. In some cases, they may not be available in all strengths or forms such as the brand.

Verapamil is also available as an extended-release oral tablet (Calan SR) and an oral immediate-release tablet (Calan). Both forms of these tablets are also available as generic medications.

What is it used for?

Verapamil extended-release forms are used to lower blood pressure .

How does it work?

Verapamil is a blocker of calcium channels. It works to relax blood vessels and improve blood flow, which helps reduce blood pressure.

This medicine affects the amount of calcium found in the heart and muscle cells. This relaxes the blood vessels, which can reduce the amount of work your heart has to do.

Side effects of Verapamil

The oral verapamil capsule may cause dizziness or drowsiness. Do not drive, operate heavy machinery or do anything that requires mental alertness until you know how it affects you. It can also cause other side effects.

The most common side effects

The most common side effects that occur with verapamil include:

  • Constipation.
  • Headache.
  • Nausea and vomiting.
  • Sexual problems, such as erectile dysfunction.
  • Weakness or fatigue

Serious side effects

If you experience any of these serious side effects, call your doctor immediately. If your symptoms are life threatening or if you think you are experiencing a medical emergency, call 911:

  • Difficult breathing
  • Dizziness or lightheadedness
  • Fainting.
  • Rapid heartbeat, palpitations, irregular heartbeat or pain in the chest.
  • Acne.
  • Slow heartbeat.
  • Swelling of your legs or ankles.

Keep in mind that drugs affect each person differently, so any information that includes all possible side effects may be incomplete. This means that you should always go to the doctor who is the one that will give you a personalized treatment.


All interactions counteract the effects of a medication.

To help avoid interactions, your doctor should handle all your medications carefully. Be sure to tell your doctor about all the medications, vitamins or herbs you are taking. To find out how this medication might interact with something else you are taking, talk to your doctor or pharmacist.

Examples of medications that can cause interactions with verapamil are listed below:

Drugs for cholesterol

The combination of certain medications for cholesterol with verapamil can cause an increase in the levels of the cholesterol medication in your body. This can cause side effects, such as severe muscle pain.

The examples are:

  • Simvastatin.
  • Lovastatin.

Drugs for heart rhythm

Dofetilide: Taking verapamil and dofetilide together can increase the amount of dofetilide in your body by a large amount. This combination can also cause a serious heart condition called torsade de pointes . Do not take these medications together.

Disopyramide: The combination of this medication with verapamil can damage the left ventricle. Avoid taking disopyramide 48 hours before or 24 hours after taking verapamil.

Flecainide: The combination of verapamil with flecainide may cause additional effects on the contractions and rhythm of your heart.

Quinidine: In certain patients, the combination of quinidine with verapamil can cause extremely low blood pressure. Do not use these drugs together.

Amiodarone: The combination of amiodarone with verapamil can change the way the heart contracts. This can cause a slow heartbeat, heart rhythm problems or reduced blood flow. You will have to be monitored very closely if you are in this combination.

Digoxin: Long-term use of verapamil can increase the amount of digoxin in your body to toxic levels. If you take any form of digoxin, you may need to reduce your dose of digoxin, and you should be monitored closely.

Beta-blockers: The combination of verapamil with beta-blockers, such as metoprolol or propranolol, can cause negative effects on heart rate, heart rate and contractions of your heart. Your doctor will monitor you closely if you are prescribed verapamil with a beta-blocker.