Verapamil is used to treat high blood pressure. Lowering high blood pressure helps prevent strokes, heart attacks, and kidney problems. Verapamil belongs to a class of drugs known as calcium channel blockers. It works by relaxing blood vessels so blood can flow more easily. Verapamil may also lower your heart rate.

This section contains uses of this drug that are not listed in the approved professional labeling for the drug but that may be prescribed by your health care professional. Use this drug for a condition that is listed in this section only if it has been so prescribed by your health care professional.

This drug may also be used for other heart diseases (such as hypertrophic cardiomyopathy, fast/irregular heartbeats). It may also be used to reduce the risk of chest pain (angina).

Take this medication by mouth with food as directed by your doctor, usually once daily in the morning or every 12 hours.

Do not crush or chew extended-release tablets. Doing so can release all of the drug at once, increasing the risk of side effects. Ask your pharmacist if the tablets may be split in half, because the directions depend on the product you take. Swallow the whole or split tablet without crushing or chewing.

The dosage is based on your medical condition and response to treatment.

Take this medication regularly to get the most benefit from it. To help you remember, take it at the same time(s) each day. Keep taking this medication even if you feel well. Most people with high blood pressure do not feel sick.

Do not stop taking this medication without consulting your doctor. Some conditions may become worse when this drug is suddenly stopped. Your dose may need to be gradually decreased.

For the treatment of high blood pressure, it may take a week before you get the full benefit of this drug.

Tell your doctor if your condition does not get better or if it gets worse (your blood pressure readings remain high or increase).

Dizziness, slow heartbeat, constipation, nausea, headache, or tiredness may occur. If any of these effects last or get worse, tell your doctor or pharmacist promptly.

To reduce the risk of dizziness and lightheadedness, get up slowly when rising from a sitting or lying position.

Remember that this medication has been prescribed because your doctor has judged that the benefit to you is greater than the risk of side effects. Many people using this medication do not have serious side effects.

Tell your doctor right away if you have any serious side effects, including:

• severe dizziness
• fainting
• new or worsening symptoms of heart failure (such as shortness of breath, swelling ankles/feet, unusual tiredness, unusual/sudden weight gain)
• very slow heartbeat

This drug may rarely cause serious (possibly fatal) liver disease. Get medical help right away if you have any symptoms of liver damage, such as:

• nausea/vomiting that doesn't stop
• loss of appetite
• stomach/abdominal pain
• yellowing eyes/skin
• dark urine

A very serious allergic reaction to this drug is rare. However, get medical help right away if you notice any symptoms of a serious allergic reaction, including:

• rash
• itching/swelling (especially of the face/tongue/throat)
• severe dizziness
• trouble breathing

This is not a complete list of possible side effects. If you notice other effects not listed above, contact your doctor or pharmacist.

In the US - Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088 or at www.fda.gov/medwatch.

In Canada - Call your doctor for medical advice about side effects. You may report side effects to Health Canada at 1-866-234-2345.

Before taking verapamil, tell your doctor or pharmacist if you are allergic to it; or if you have any other allergies. This product may contain inactive ingredients, which can cause allergic reactions or other problems. Talk to your pharmacist for more details.

Before using this medication, tell your doctor or pharmacist your medical history, especially of:

• certain types of heart rhythm problems (such as second- or third-degree atrioventricular block, sick sinus syndrome unless you have a pacemaker, Wolff-Parkinson-White syndrome, Lown-Ganong-Levine syndrome)
• heart failure
• certain muscle/nerve disorders (muscular dystrophy, myasthenia gravis)
• liver disease
• kidney disease

This drug may make you dizzy. Alcohol or marijuana (cannabis) can make you more dizzy. Do not drive, use machinery, or do anything that needs alertness until you can do it safely. Limit alcoholic beverages. Talk to your doctor if you are using marijuana (cannabis).

Before having surgery, tell your doctor or dentist about all the products you use (including prescription drugs, nonprescription drugs, and herbal products).

Older adults may be more sensitive to the side effects of this drug, especially constipation, or swelling ankles/feet.

During pregnancy, this medication should be used only when clearly needed. Discuss the risks and benefits with your doctor.

This medication passes into breast milk, but is unlikely to harm a nursing infant. Consult your doctor before breastfeeding.

Drug interactions may change how your medications work or increase your risk for serious side effects. This document does not contain all possible drug interactions. Keep a list of all the products you use (including prescription/nonprescription drugs and herbal products) and share it with your doctor and pharmacist. Do not start, stop, or change the dosage of any medicines without your doctor's approval.

Some products that may interact with this drug include:

• aliskiren
• clonidine
• disopyramide
• dofetilide
• fingolimod
• labetalol
• lithium

Other medications can affect the removal of verapamil from your body, which may affect how verapamil works. Examples include erythromycin, rifamycins (such as rifampin), ritonavir, St. John's wort, among others.

Verapamil can slow down the removal of other medications from your body, which may affect how they work. Examples of affected drugs include asunaprevir, colchicine, elacestrant, fezolinetant, flibanserin, ivabradine, lomitapide, midazolam, triazolam, among others.

Some products have ingredients that could raise your heart rate or blood pressure. Tell your pharmacist what products you are using, and ask how to use them safely (especially cough-and-cold products, diet aids, or NSAIDs such as ibuprofen/naproxen).

If someone has overdosed and has serious symptoms such as passing out or trouble breathing, call 911. Otherwise, call a poison control center right away. US residents can call 1-800-222-1222. Canada residents can call 1-844-764-7669. Symptoms of overdose may include: very slow heartbeat, severe dizziness, fainting.

Do not share this medication with others.

Lifestyle changes that may help this medication work better include exercising, stopping smoking, and eating a low-cholesterol/low-fat diet. Consult your doctor for more details.

Lab and/or medical tests (such as liver function) should be done while you are taking this medication. Keep all medical and lab appointments. Consult your doctor for more details.

Check your blood pressure and pulse (heart rate) regularly while taking this medication. Learn how to check your own blood pressure and pulse at home, and share the results with your doctor.

There are different brands and types of this medication available. Some do not have the same effects. Do not change brands or types without consulting your doctor or pharmacist.

If you miss a dose, take it as soon as you remember. If it is near the time of the next dose, skip the missed dose. Take your next dose at the regular time. Do not double the dose to catch up.

Store at room temperature away from light and moisture. Do not store in the bathroom. Keep all medications away from children and pets.

Do not flush medications down the toilet or pour them into a drain unless instructed to do so. Properly discard this product when it is expired or no longer needed. Consult your pharmacist or local waste disposal company.

Your condition can cause complications in a medical emergency. For information about enrolling in MedicAlert, call 1-888-633-4298 (US) or 1-800-668-1507 (Canada).