11 Verapamil Interactions You Should Know About

Verapamil (Calan SR, Verelan) belongs to a class of medications known as calcium channel blockers. It’s commonly used to treat high blood pressure, chest pain, and irregular heartbeat. It’s also used off-label to prevent headaches. 

Verapamil may interact with other medications. These interactions can make it more likely to experience side effects from verapamil. But what verapamil interactions do you need to know about? And what are the signs that an interaction is occurring? 

Below, we’ll discuss 11 of the most common verapamil interactions to be aware of.

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1. Simvastatin and lovastatin

Simvastatin (Zocor) is a statin medication used to treat high cholesterol. Verapamil can increase simvastatin levels in your body if they’re taken together. This can lead to an increased risk of statin-related side effects, like muscle pain and breakdown (rhabdomyolysis). Doses of simvastatin should be limited to 10 mg/day if you’re also taking verapamil.

This interaction is also seen with lovastatin. Lower doses of lovastatin (no more than 40 mg) are recommended if you also take verapamil. 

If you experience side effects from this interaction, let your provider know. They may switch you to a different statin or try a different cholesterol medication. 

2. Beta blockers and other blood pressure medications

Beta blockers are also medications used for heart-related conditions. They’re also used for glaucoma, migraine prevention, and essential tremors.

Some people will need to take beta blockers and verapamil. But the combination also has risks. Verapamil and beta blockers can have similar actions in the body, so combining them can cause your heart rate to slow down too much (bradycardia). It can also make heart contractions weaker and lower your blood pressure too much. Symptoms of this interaction may include dizziness, difficulty breathing, and fatigue.

If you take verapamil with other blood pressure medications, your blood pressure may also drop too low. These include medications like clonidine or angiotensin-converting enzyme (ACE) inhibitors. Your healthcare provider may ask you to check your blood pressure more often if you’re taking verapamil with these medications. If you experience low blood pressure, or any of the above symptoms, let your provider know. If you’re experiencing serious symptoms, like difficulty breathing, seek emergency care.

3. Alcohol

Verapamil can cause your body to process alcohol much slower than normal. This can lead to a higher blood alcohol level, which can make you feel more “drunk.” This puts you at risk for falls, injuries, and even alcohol poisoning. 

Due to this interaction, it’s best to avoid alcohol while taking verapamil. If you have questions about alcohol and verapamil, talk to your healthcare provider.

4. Grapefruit juice

Some research has shown that grapefruit doesn’t interact with verapamil. But there have been some reports of verapamil toxicity as a result of drinking grapefruit juice. When taken together, grapefruit may increase verapamil levels in your blood. Too much verapamil can cause low blood pressure and bradycardia. This can make you feel dizzy, tired, and out of breath. In severe cases, it can be fatal.

If drinking grapefruit juice is something you’d rather not give up, talk to your healthcare provider. They may recommend an alternative to verapamil. 

5. Digoxin

Digoxin (Lanoxin) is a medication used to treat heart failure and abnormal heart rhythm (arrhythmias). Its levels are often closely monitored throughout treatment. This is because it has a high risk of toxicity.

If you’re already taking verapamil when you start digoxin, your blood levels of digoxin may increase above what’s considered safe. This can lead to digoxin toxicity. Symptoms can include nausea, loss of appetite, and vision changes. In severe cases, it can worsen your arrhythmia or cause trouble breathing. 

If you’re taking verapamil, your healthcare provider may start you at a lower digoxin dose. And they’ll check your digoxin levels often if you’re taking it with verapamil. Be sure to keep up with your appointments and follow your provider’s instructions. This will help you avoid issues with this interaction.

6. Flecainide

Flecainide is another medication used to treat arrhythmias. Like digoxin, flecainide can cause toxicity. If you take flecainide, your healthcare provider may monitor your blood levels. 

Combining flecainide and verapamil can cause your heart to beat slower and other heart problems. This can cause various symptoms, such as chest pain, difficulty breathing, and fainting.

If you take flecainide and verapamil, let your healthcare provider know right away if you experience any of these symptoms. They may need to make a change to your medications. If your symptoms are severe, seek emergency care.

7. Lithium

Lithium is a mood stabilizer used to treat bipolar disorder. Lithium levels are monitored closely due to its high risk of side effects and toxicity. It also can interact with a lot of medications. 

The combination of verapamil and lithium may worsen lithium side effects. These include slow heart rate, low blood pressure, and diarrhea. This combination may also raise the risk for damage to the brain and nervous system (neurotoxicity) — which can lead to confusion, nerve pain, and movement disorders.

If you need to take these medications together, your healthcare provider will check your lithium levels to make sure they stay in a safe range.

8. Carbamazepine

Carbamazepine (Tegretol) is a medication used to treat seizures and certain types of bipolar disorder. Carbamazepine also carries a high risk of side effects and drug interactions.

Verapamil can increase carbamazepine levels in the body. This can increase the risk of carbamazepine side effects, like dizziness, headache, and vision problems. In serious cases, coma, heart problems, and breathing issues are possible.

If you’re taking these medications together, your healthcare provider may need to adjust your carbamazepine dose. Be sure to let them know if you experience any of the above side effects. 

9. Rifampin

Rifampin is an antibiotic. It’s used to prevent and treat tuberculosis and meningococcal infections.

Rifampin can significantly lower verapamil levels in the body. This can make verapamil less effective. Your healthcare provider may change your verapamil dose if you’re taking rifampin to keep levels where they should be. 

10. Phenobarbital

Phenobarbital belongs to a group of medications called barbiturates. It’s used to treat seizures, insomnia (trouble sleeping), and alcohol withdrawal. 

Phenobarbital can lower verapamil levels in the body. This can prevent verapamil from working as well. If you take phenobarbital, your healthcare provider may adjust your verapamil dose to make sure you take a dose that’s effective. 

11. Cyclosporine

Cyclosporine (Sandimmune) is an immunosuppressant used to prevent organ transplant rejection. Cyclosporine also requires frequent blood tests to make sure your levels aren’t too high or low. 

Verapamil can increase cyclosporine levels in the body. This can put you at a higher risk for cyclosporine toxicity and side effects. Symptoms of this include irregular heartbeat, difficulty breathing, and seizures.

Your healthcare provider will watch your cyclosporine levels closely throughout treatment. But let them know if you develop any symptoms of cyclosporine toxicity.

When should I contact my healthcare provider about a verapamil interaction?

If you experience any side effects that are unusual or bothersome, reach out to your healthcare provider. These can include signs that verapamil isn’t working, like high blood pressure. You should also watch for signs that your blood pressure is too low, which may include dizziness or fatigue.

Let your healthcare provider and pharmacist know what medications you take. The best way to do this is to keep a list of your current prescription medications, OTC medications, and supplements. Your provider and pharmacist can use this list to check for verapamil interactions.

Don’t change or stop taking your medication without your provider’s okay. Doing so could make a possible interaction worse. 

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Written by:

Stacia Woodcock, PharmD

Stacia Woodcock, PharmD, is a pharmacy editor for GoodRx. She earned her Doctor of Pharmacy degree from the University of Kentucky and is licensed in New York and Massachusetts.

Edited by:

Amy B. Gragnolati, PharmD, BCPS

Amy Gragnolati, PharmD, BCPS, is a pharmacy editor for GoodRx. Amy currently holds her pharmacist license in Georgia and California.

Reviewed by:

ThienLy Neal, PharmD

ThienLy Neal, PharmD, has over 10 years experience in the pharmacy field, including in such settings as retail, hospital, compounding, and managed care. She has led various clinical programs while focusing on medication adherence programs, specialty drug initiatives, and polypharmacy safety initiatives.

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