In this drug factsheet:
What side effects are possible with this medication?
Many medications can cause side effects. A side effect is an unwanted response to a medication when it is taken in normal doses. Side effects can be mild or severe, temporary or permanent.
The side effects listed below are not experienced by everyone who takes this medication. If you are concerned about side effects, discuss the risks and benefits of this medication with your doctor.
The following side effects have been reported by at least 1% of people taking this medication. Many of these side effects can be managed, and some may go away on their own over time.
Contact your doctor if you experience these side effects and they are severe or bothersome. Your pharmacist may be able to advise you on managing side effects.
- unusual tiredness or weakness
Although most of the side effects listed below don't happen very often, they could lead to serious problems if you do not check with your doctor or seek medical attention.
Check with your doctor as soon as possible if any of the following side effects occur:
- breathing difficulty, coughing, or wheezing
- dizziness, lightheadedness, or fainting
- irregular or fast, pounding heartbeat
- muscle weakness
- skin rash
- slow heart rate (less than 50 beats per minute)
- swelling of ankles, feet, or lower legs
Stop taking the medication and seek immediate medical attention if any of the following occur:
- signs of a serious allergic reaction (e.g., abdominal cramps, difficulty breathing, nausea and vomiting, or swelling of the face and throat)
Some people may experience side effects other than those listed. Check with your doctor if you notice any symptom that worries you while you are taking this medication.
Are there any other precautions or warnings for this medication?
Before you begin using a medication, be sure to inform your doctor of any medical conditions or allergies you may have, any medications you are taking, whether you are pregnant or breast-feeding, and any other significant facts about your health. These factors may affect how you should use this medication.
Heart Failure: Verapamil works partially by reducing the force of the heart’s contractions which can cause the symptoms of heart failure to become worse. If you have heart failure that is not well-corrected, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.
Kidney function: Kidney disease or reduced kidney function may cause this medication to build up in the body, causing side effects. If you have reduced kidney function or kidney disease, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.
Liver function: Liver disease or reduced liver function may cause this medication to build up in the body, causing side effects. If you have liver problems, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed. Your doctor may want to test your liver function regularly with blood tests while you are taking this medication.
Verapamil may also reduce liver function and can cause liver failure. If you experience symptoms of liver problems such as fatigue, feeling unwell, loss of appetite, nausea, yellowing of the skin or whites of the eyes, dark urine, pale stools, abdominal pain or swelling, and itchy skin, contact your doctor immediately.
Low blood pressure and heart rate: Low blood pressure symptoms of tiredness and weakness with faintness have been reported following single doses and even after some months of treatment with verapamil. Some people may require a reduced dose. Verapamil can cause very low heart rate for some people. Report an abnormally low heart rate (less than 50 beats per minute) or persistent fatigue to your doctor.
Neuromuscular Disease: If you have a neuromuscular disease such as myasthenia gravis, Lambert-Eaton syndrome, or Duchenne's muscular dystrophy, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.
Pregnancy: Verapamil reaches the developing baby if it is taken during pregnancy. This medication should not be used during pregnancy unless the benefits outweigh the risks. If you become pregnant while taking this medication, contact your doctor immediately.
Breast-feeding: This medication passes into breast milk. If you are a breast-feeding mother and are taking verapamil, it may affect your baby. Talk to your doctor about whether you should continue breast-feeding.
Children: The safety and effectiveness of using this medication have not been established for children.
Seniors: Seniors may have a higher risk of side effects with this medication. Your doctor may recommend lower doses to reduce this risk.
What other drugs could interact with this medication?
There may be an interaction between verapamil and any of the following:
- alpha agonists (e.g., clonidine, methyldopa)
- alpha blockers (e.g., alfuzosin, doxazosin, tamsulosin)
- amphetamines (e.g., dextroamphetamine, lisdexamphetamine)
- angiotensin converting enzyme inhibitors (ACEIs; captopril, enalapril, ramipril)
- angiotensin receptor blockers (ARBs; e.g., candasartan, irbesartan, losartan)
- anti-cancer medications (e.g., cabazitaxel, docetaxel; doxorubicin; etoposide, ifosfamide, irinotecan, vincristine)
- "azole" antifungals (e.g., ketoconazole, fluconazole)
- barbiturates (e.g., butalbital, pentobarbital, phenobarbital)
- benzodiazepines (e.g., diazepam, lorazepam)
- beta-blockers (e.g., propranolol, metoprolol)
- other calcium channel blockers (e.g., amlodipine, diltiazem, nifedipine)
- calcium salts (e.g., calcium carbonate, calcium gluconate)
- certain medications that affect your immune system (e.g., cyclosporine, sirolimus, tacrolimus, everolimus)
- corticosteroids (e.g., budesonide, dexamethasone, fluticasone, hydrocortisone, prednisone)
- diuretics (water pills; e.g., furosemide, hydrochlorothiazide, triamterene)
- estrogens (e.g., conjugated estrogen, estradiol, ethinyl estradiol)
- "gliptin" diabetes medications (e.g., linagliptin, saxagliptin, sitagliptin)
- grapefruit juice
- HIV non-nucleoside reverse transcriptase inhibitors (NNRTIs; e.g., delaviridine, efavirenz, etravirine, nevirapine)
- HIV protease inhibitors (e.g., atazanavir, indinavir, ritonavir, saquinavir)
- macrolide antibiotics (e.g., clarithromycin, erythromycin, telithromycin)
- monoamine oxidase inhibitors (MAOIs; e.g., moclobemide, phenelzine, rasagiline, selegiline, tranylcypromine)
- neuromuscular blocking agents (e.g., atracurium, pancuronium)
- non-steroidal anti-inflammatory medications (NSAIDS; e.g., ibuprofen, naproxen)
- other medications that treat abnormal heart rhythms (e.g., disopyramide, flecainide, propafenone, quinidine)
- nitrates (e.g., isosorbide dinitrate, isosorbide mononitrate)
- phosphodiesterase 5 inhibitors (e.g., sildenafil, tadalafil, vardenafil)
- progestins (e.g., dienogest, levonorgestrel, medroxyprogesterone, norethindrone)
- proton pump inhibitors (e.g., lansoprazole, omeprazole)
- St. John's wort
- selective serotonin reuptake inhibitors (SSRIs; e.g., citalopram, duloxetine, fluoxetine, paroxetine, sertraline)
- "statin" medications (e.g., atorvastatin, lovastatin, simvastatin)
- tricyclic antidepressants (e.g., amitriptyline, desipramine, imipramine)
If you are taking any of these medications, speak with your doctor or pharmacist. Depending on your specific circumstances, your doctor may want you to:
- stop taking one of the medications,
- change one of the medications to another,
- change how you are taking one or both of the medications, or
- leave everything as is.
An interaction between two medications does not always mean that you must stop taking one of them. Speak to your doctor about how any drug interactions are being managed or should be managed.
Medications other than those listed above may interact with this medication. Tell your doctor or prescriber about all prescription, over-the-counter (non-prescription), and herbal medications you are taking. Also tell them about any supplements you take. Since caffeine, alcohol, the nicotine from cigarettes, or street drugs can affect the action of many medications, you should let your prescriber know if you use them.
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