Calcium blocker side effects

What Are Calcium Channel Blockers?

Calcium channel blockers are prescribed for high blood pressure and heart problems, but be careful when using one with diuretics, ACE inhibitors, or other drugs.

Calcium channel blockers are a class of drugs prescribed for high blood pressure and other heart diseases.

The medications reduce blood pressure by helping blood vessels to relax.

Calcium channel blockers reduce the speed at which calcium moves into heart muscle, blood vessels, and cells in the heart that control your heart rate.

The drugs increase the diameter of blood vessels, reduce the force of contraction of the heart, and slow heart rate, all of which helps keep your heart from having to work as hard.

In addition to high blood pressure (hypertension), calcium channel blockers are prescribed to treat:

  • Angina (chest pain)
  • Arrhythmia (irregular heartbeat)

These medications typically aren’t prescribed for people who have congestive heart failure or structural heart problems.

Examples of Calcium Channel Blockers

There are many different generic and brand-name forms of calcium channel blockers available, including:

Typical Calcium Channel Blocker Interactions

Calcium channel blockers may interact with other medications, so always tell your doctor about every medication, recreational drug, vitamin, and supplement — whether over-the-counter (OTC) or prescription — that you are taking.

Calcium channel blockers should always be taken with a meal or a glass of milk to protect the stomach.

You should not, however, take calcium channel blockers with grapefruit juice or grapefruit.

Grapefruit (and its juice) can alter the effects of many drugs, including calcium channel blockers.

Some of the drugs that are likely to interact with calcium channel blockers include:

  • Other high blood pressure medications, including ACE (angiotensin-converting enzyme) inhibitors or beta blockers
  • Diuretics (water pills)
  • Some eye medications
  • Large amounts of vitamin D or calcium supplements
  • Drugs used to treat arrhythmia
  • Digitalis, also called digitoxin (Digoxin)
  • Drugs that contain cortisone, or any corticosteroids

Remember to take calcium channel blockers exactly as your doctor or pharmacist recommends.

This means not crushing, chopping, or dissolving these medications unless you’re told it’s okay — especially if you’re taking a medication that ends in XL or XR, which means extended release.

Cutting pills will negate that effect, and possibly cause adverse effects.

Calcium Channel Blocker Side Effects

It’s also important to avoid drinking alcohol when taking calcium channel blockers.

Alcohol, combined with a calcium channel blocker, can cause severe side effects and may also affect the way the medication works.

Side effects from taking calcium channel blockers are usually fairly mild, but may include:

  • Weight gain
  • Swelling in the lower legs, feet, or ankles
  • Feeling dizzy
  • An increase in appetite
  • Constipation
  • Feeling tired or drowsy
  • A heartbeat that feels rapid, slow, or irregular
  • Coughing, wheezing, or problems with breathing or swallowing
  • Nausea or stomach discomfort
  • Numbness or a tingling sensation in the feet or hands

Calcium channel blockers are generally safe, but like any medication, need to be taken properly and with care.

To lessen the chance of interactions, always tell your doctor about other medications you’re taking.

And remember that you don’t have to deal with side effects: Talk to your doctor about them.

Chances are that a slight adjustment in the dosage or the way you take your medication will help you feel better while allowing you to get the treatment you need.

What is this medication?

Calcium Channel blockers (CCBs) are sometimes called calcium channel antagonists.

Calcium channel blockers include:

Be aware:

  • Generic names are listed first.
  • Canadian brand names are in brackets.
  • This list doesn’t include every brand name.
  • If your prescription isn’t listed, your pharmacist is the best source for more information.
What does it do?

CCBs help control high blood pressure, chest pain caused by heart disease and arrhythmia.
CCBs are vasodilators. This means they widen and relax your blood vessels. This can help:

  • Lower blood pressure
  • Slow your heartbeat
  • Control an irregular heartbeat
  • Reduce chest pain

Be Aware: CCBs are often taken with other medications, such as beta-blockers or diuretics.

How do I take it?

There are many different kinds of calcium channel blockers. How much medicine you need will depend on the CCB you are taking.

You and your healthcare provider will determine the type and dose that’s right for you.

Be Aware: If you are taking an “extended-release” CCB, never chew, cut, crush, or dissolve the pills.

Are there any interactions?

Some medications can stop your heart medicine from working properly. They may even cause other health problems.

Prescription and non-prescription medications can interact with CCBs. These include:

  • ACE inhibitors
  • Antiarrhythmics
  • Diuretics
  • Digitalis
  • Corticosteroids
  • Calcium or vitamin D supplements

Avoid grapefruit and grapefruit juice (fresh or frozen). It can boost the effect of some CCBs. This could make your blood pressure too low.

Visit Health Canada to learn more about The Effects of Grapefruit and its Juice on Certain Drugs.

Avoid smoking. CCBs and smoking can cause rapid heartbeat (tachycardia).

Tell your healthcare provider and pharmacist about all the medications you are taking. These include:

  • Prescription drugs
  • Non-prescription drugs
  • Inhalers
  • Creams or ointments
  • Over-the-counter or natural health products
  • Alternative therapies
  • Vitamins, minerals, or supplements
  • Herbal remedies
  • Homeopathic medicines
  • Traditional remedies, such as Chinese medicines
Are there any side effects?

CCBs have relatively few side effects. And they tend to be irritating vs. serious.

Side effects may include:

  • Fatigue
  • Dizziness
  • Heartburn
  • Swelling in your ankles or feet

Be aware: It is not safe to stop taking a CCB without consulting your healthcare provider.

If you have side effects, talk to your pharmacist or healthcare provider.

Lifestyle changes that can also help

There are two ways to control and manage your heart health: medication and lifestyle.

Medication can help you control heart disease and high blood pressure, but it cannot cure it.

A healthy lifestyle can help you keep medication to a minimum.

Visit Learn how to keep your heart healthy with current information and advice from Heart and Stroke Foundation experts.

Talk to your healthcare provider about the most beneficial lifestyle goals for you.

Related information

Your healthcare provider or pharmacist are your best sources of information. You can also learn more about medications at any of these trusted sites.

Health Canada – Drugs and Health Products
Provides health and medical information for Canadians to maintain and improve their health.

Learn more about:

  • Safe Use of Medicines
  • Safety and Effectiveness of Generic Drugs
  • Buying drugs over the Internet
  • Drug Product Database
  • MedEffect Canada
    Provides safety alerts, public health advisories, warnings and recalls.

Your ministry of health also offers health resources in your province or territory. For example, Ontario’s MedsCheck program provides free pharmacist consultations. And British Columbia’s Senior Healthcare web page provides information about important health programs.

Drug coverage

Calcium Channel Blockers

How These Blood Pressure Drugs Cause Early Death and Promote Cancer

Dangerous Drugs

Among the top 10 drugs prescribed in the U.S. are blood pressure drugs called calcium channel blockers. Calcium channel blockers are prescribed for hypertension (high blood pressure), heart arrhythmias (irregular heart beats), and angina (chest pain.)

Unfortunately, research shows that these drugs make one far more susceptible to dying of a heart attack (resulting in early death) as well as potentiating cancer. These expensive drugs allow the sick to get sicker as well as leading the way to cancer.

What are calcium channels?

Each body cell has an outer membrane with a sandwich of fats called lipids. The layers in the sandwich contain a wonderful host of protective nutrients, including EPA (eico-sapentaenoic acid), phosphatidyl choline, vitamin E and others. The cell’s membrane is studded with pores called “calcium channels,” which pump calcium ions into the cell from outside the cell.

In normal daily operation, calcium ions pass back and forth through the calcium channels in the cell’s membrane, repeatedly, many thousands of times per day. Inside the cell, calcium is needed in the mitochondria (where energy is made) and in the endoplasmic reticulum (where drugs, toxins, hormones, etc. are detoxified). Outside the cell, calcium is used in hundreds of bodily reactions.

Calcium can passively flow out of the cell, but for calcium to re-enter, the cell requires the use of the calcium channel pump. Pumping calcium through the calcium channel requires: a) energy and b) depends upon the cell’s membrane sandwich to have the exact types of layers in the membrane. The channel partly runs on an electric current that is generated by the polarized side arms that protrude from the cell’s sandwich. If the right layers are not in the sandwich, the electric current cannot flow properly to open the calcium channel. Hence, the calcium pump will not work correctly. In effect, it is broken.

Normally, the synchronized contraction of the heart muscle is brought about by the flow of ions through these channels. Many nutrients that feed and nourish the cell also flow through these channels. When a cell is damaged from toxins or junk foods (such as hydrogenated oils) or lacks critical nutrients, such as phosphatidyl choline, the calcium pump will not work well. Massive amounts of calcium leak back into the cell and cannot be pumped out again. With its interior flooded with calcium and no way to get it out, the cell malfunctions at first, then later dies.

How do calcium channel blocker drugs work?

Calcium channel blocker drugs are designed to block the channel where the calcium is leaking into the cell. These drugs slowly close off these crucial regulatory channels, but over time, the calcium channel essentially stops functioning at all. At first, symptoms of high blood pressure or chest pain may improve, but later on, these drugs so badly poison the channels that they are known to cause many terrible symptoms, including heart failure, risk of cancer and early death.

Blocking the flow of calcium is dangerous since calcium is essential for normal cell life and operation – as well as for the whole body. Without sufficient calcium, you cannot live.

60% Increased Risk of Heart Attack

The Wall Street Journal (winter, l996) reported that patients who took calcium channel blockers had 60% more chance of dying of a heart attack. This is because calcium channel blocker drugs take a system that is functioning poorly and damage it even more.

Many previous studies have associated calcium channel blockers with increased heart attacks, increased risk of breast cancer, increased suicide risk, and increased gastrointestinal bleeding. Short-acting versions of these drugs have been previously shown to be dangerous and now long-acting versions are being shown to be possibly dangerous as well.

In August, 2000, a report from the “Meeting of the European Society of Cardiology in Amsterdam (Netherlands)” showed that despite lowering blood pressure, calcium channel blockers did not reduce the death rate. The real goal of a therapy should not be only to reduce blood pressure or to control any other bodily parameter. The real goal should be to help achieve a longer, healthier, happier life.

You may wonder how long it takes for a person on calcium channel blockers to experience a catastrophy, such as a heart attack, stroke, cancer, etc. It depends on the person’s physical strengths (such as their total nutrient reserves) and their weaknesses (such as their total load of toxic stressors). The poorer the person’s nutrition, and the greater their toxic load, the more likely they will develop further problems.

How do calcium channel blockers lead to cancer?

Closely related to calcium channels are structures called gap junctions. Although these act somewhat like channels, they are actually little protein tubules that connect cells one to another. Normal cells have fully functioning gap junctions. Through these gap junctions, cells are able to communicate with each other and give each other constant feedback to be able to keep the body working in harmony. No cell should work alone, cut off from the others.

To initiate cancer, several steps are involved. First, calcium channel blocker drugs work by intentionally poisoning the calcium channels. This in turn, leads to a break down in the closely allied gap junctional proteins. As the gap proteins are damaged more and more, cell-to-cell communication begins to falter. In cancer, the cancer cells have lost their gap junctional proteins. Signals that should run from cell to cell are absent, so cells do not know when to stop growing. With cell-to-cell communication lost, cancer cells can grow wildly out of control.

Many toxic compounds can poison cells and cause them to lose their cell-to-cell communication link. In addition to calcium channel blocker drugs, pesticides and environmental toxins can damage gap junctions. To reverse the process, many nutrients can help repair and regenerate the gap junctions. (See “Key Nutrients.”)

What should you do?

Taking calcium channel blocker drugs for high blood pressure ignores the real problem: the need to improve the nutrient supply to repair the cell’s membrane. Key nutrients are needed to re-establish normal cellular functioning. First, you must identify the nutrient deficiencies that have created the problem in the first place, then use high quality nutrients to repair and rebuild the cells. By using targeted nutrients along with an improved diet, we have repeatedly seen many cases of high blood pressure resolve, eliminating the need to use drugs.

If you are taking a calcium channel blocker for high blood pressure, we urge you to discuss with your doctor switching to a less dangerous blood pressure drug. If your doctor does not want to switch medications, you may want to seek a second opinion. Since the use of calcium channel drugs is potentially dangerous and even life-threatening, the time for you to act is now. However, do not try to discontinue these drugs on your own. You need to be under the supervision of a medical doctor.

For a list of safer blood pressure drugs to use, please see the consumer-friendly book, Best Pills, Worst Pills (ed. Sidney M. Wolfe, M.D.), in which a panel of over 50 medical doctors evaulate various blood pressure drugs and recommend the ones with the safest track record. In the meantime, begin using top quality nutrients to begin to rebuild faulty cell membranes and re-establish normal cell function so your body can regulate its own blood pressure just as it was designed.

The Heart and Blood Pressure Support Program

I. Key Nutrients

To help the body heal itself, rebuild faulty cell membranes and restore normal blood pressure, the following key nutrients are highly recommended for daily use:

1) Coral minerals from the Sango marine reef (which contains highly ionized calcium and magnesium as well as many trace minerals) to alkalinize the cell’s pH to help establish normal blood pressure and artery function (The coral ratio should be 25% calcium to 13% magnesium.)
2) USP grade Norwegian cod liver oil, mercury-free (which naturally contains EPA and DHA) to help rebuild and strengthen cell membranes
3) All four phosphatidyl complexes from non-GMO soy (including phosphatidylcholine, phosphatidylserine, phosphatidylinositol and phosphatidylethanolamine) which help to rapidly rebuild and strengthen cell membranes
4) Anti-infective herbs, such as Italian olive leaf extract, a key herb proven to help normalize elevated blood pressure
5) Key heart-regulating herbs, which help target anti-infective herbs such as olive leaf extract to the heart
6) Colostrum, a key compound which contains many immune-boosting factors as well as a vast array of healthy cell nutrients for tissue regeneration and healing

II. Optimize Your Diet

Adopt a high fiber, unprocessed, plant-based diet, rich in fresh fruits, vegetables and whole grains. Eat at least one raw meal daily (such as a large salad with organic greens and vegetables). Avoid eating commercially produced foods from supermarkets or restaurants.

Instead, enjoy making homemade meals with fresh, organic foods. Avoid contaminated foods such as commercial red meat, commercial dairy products and foods with “junk” oils such as fried or hydrogenated oils.

III. Exercise

Regular exercise is important, especially a daily 20-minute walk (minimum time to promote lymph drainage) in fresh air and sunshine. If walking is not possible, begin with gentle stretching exercises and deep breathing exercises until you are able to do more.

Common Consumer Brand Names (with the generic name in parentheses)

Potential Side Effects

Abdominal pain

Altered sense of smell or taste


Back Pain

Chest pain

Cold, clammy skin





Difficult or labored breathing

Difficulty swallowing


Dry mouth

Dry skin

Eye pain


Fatigue Fluid retention and swelling



General feeling of illness

Hair loss


Heart failure

Hot flashes

Inability to sleep

Increased sweatingIndigestion

Irregular heartbeat

Joint pain

Lack of coordination

Loss of appetite

Loss of memory

Muscles cramps

Muscle weakness

Nasal inflammation




Painful urination


Sexual problems

Skin discoloration


Tingling or “pins and needles”



Urinating at night

Urinating problems

Vision problems



Weight gain

and many more symptoms

  1. Mercola, J. “Calcium Channel Blockers Found Ineffective and May Increase Death Rate,” Townsend Newsletter For Doctors, Dec., 2000, 43.
  2. Rogers, S, “How Common Heart Drugs Cause Cancer,” in Depression Cured At Last, SK Publishing: Sarasota, FL, 1996, 688-92. Ruch, RJ, “The role of gap junctional intercellular communication in neoplasia (review),” Ann Clin Lab Sci, 24(3):216-231, May-June, 1994.
  3. Ruch, RJ, Klaunig JE, “Effects of tumor promoters, genotoxic carcinogens and hepatocytotoxins on mouse heptocyte intercellular communication,” Cell Biol Toxicol 2:4, 469-483, 1986. (Tells how prescription drugs, pesticides and food additives damage gap junctions and promote cancer.)

Calcium channel blockers

Calcium channel blockers lower your blood pressure by preventing calcium from entering the cells of your heart and arteries. Calcium causes the heart and arteries to contract more strongly. By blocking calcium, calcium channel blockers allow blood vessels to relax and open.

Some calcium channel blockers have the added benefit of slowing your heart rate, which can further lower your blood pressure, relieve chest pain (angina) and control an irregular heartbeat.

Calcium channel blockers are also called calcium antagonists.

Medically reviewed by Last updated on Sep 19, 2019.

Examples of calcium channel blockers

Calcium channel blockers are available in short-acting and long-acting forms. Short-acting medications work quickly, but their effects last only a few hours. Long-acting medications are slowly released to provide a longer lasting effect.

Several calcium channel blockers are available. Which one is best for you depends on your health and the condition being treated.

Examples of calcium channel blockers include:

  • Amlodipine (Norvasc)
  • Diltiazem (Cardizem, Tiazac, others)
  • Felodipine
  • Isradipine
  • Nicardipine
  • Nifedipine (Adalat CC, Procardia)
  • Nisoldipine (Sular)
  • Verapamil (Calan, Verelan)

In some cases, your doctor might prescribe a calcium channel blocker with other high blood pressure medications or with cholesterol-lowering drugs such as statins.

When calcium channel blockers are used

In addition to high blood pressure, doctors prescribe calcium channel blockers to prevent, treat or improve symptoms in a variety of conditions, such as:

  • Coronary artery disease
  • Chest pain (angina)
  • Irregular heartbeats (arrhythmia)
  • Some circulatory conditions, such as Raynaud’s disease

For black people and older people, calcium channel blockers might work better than other blood pressure medications, such as beta blockers, angiotensin-converting enzyme (ACE) inhibitors or angiotensin II receptor blockers.

Side effects

Side effects of calcium channel blockers may include:

  • Constipation
  • Dizziness
  • Fast heartbeat (palpitations)
  • Fatigue
  • Flushing
  • Headache
  • Nausea
  • Rash
  • Swelling in the feet and lower legs

Avoid grapefruit products while taking certain calcium channel blockers. Grapefruit juice interacts with the drug and can affect heart rate and blood pressure. This can cause symptoms such as headaches and dizziness.

The clinical equivalence of generic and brand-name calcium channel blockers

Posted 31/01/2011

However, the limited investigation and assumption of the equivalence with regard to safety and efficacy is a source of concern for consumers, both patients and prescribers alike. There are concerns over the clinical validity of generic substitution with amlodipine salt forms. Several attempts at reviewing the literature to determine the possible therapeutic equivalence of generic and brand-name calcium channel blockers have been performed .


Seven articles were identified by Kesselheim et al. as evaluating the clinical outcomes of generic and brand-name versions of calcium channel blockers in the period studied (1984–2008) . The largest of these studies involved 189 outpatient subjects with uncomplicated essential hypertension in a multi-centre, double-blind, parallel group randomised controlled trial . This study reported significant improvements in blood pressure in both the group taking amlodipine camsylate and the group taking Norvasc over the eight-week study period, with no statistical differences in tolerability between the two groups.

One study, performed with 24 subjects taking either Norvasc or amlodipine maleate reported a decrease in systolic blood pressure, an increase in heart rate, and a decrease in the PR and QRS intervals of the ECG with no difference between the two groups. Similar results were obtained with the studies investigating Calan versus verapamil, Cardizem versus long-acting diltiazem, Calan SR or Isoptin SR versus sustained release verapamil; these small bioequivalence studies reported changes in heart rate, blood pressure, ECG changes, complete blood count, urine analysis, but with no significant differences between groups.


Long-term clinical studies on commercial amlodipine maleate salt preparations are needed to determine if any differences in clinical outcome occur.

The therapeutic equivalence of brand-name and generic narrow therapeutic index (NTI) cardiovascular drugs

The therapeutic equivalence of antiplatelet agents, ACE-inhibitors, statins and alpha-blockers

The clinical equivalence of brand-name beta-blockers and their generic counterparts

Are generic diuretics clinically equivalent to their brand-name counterparts for the management of cardiovascular disease?

Generic or brand-name drugs for cardiovascular disease? Does the evidence match current opinion?

The rise in power of generic drugs

2. Meredith PA. Potential concerns about generic substitution: bioequivalence versus therapeutic equivalence of different amlodipine salt forms. Curr Med Res Opin. 2009;25(9):2179-89.

3. Kim SH, Kim YD, Lim DS, Yoon MH, Ahn YK, On YK, et al. Korean Multicenter Amlodipine Study Investigators. Results of a phase III, 8-week, multicenter, prospective, randomized, double-blind, parallel-group clinical trial to assess the effects of amlodipine camsylate versus amlodipine besylate in Korean adults with mild to moderate hypertension. Clin Ther. 2007;29(9):1924-36.

Calcium Channel Blockers

Calcium Channel Blockers Include:


These drugs are used to slow the heart rate (irregular heart beat) and reduce blood pressure (hypertension). They can also be used for the treatment of angina (chest pain).


Take this drug exactly as prescribed. Take it at the same time(s) each day. Sustained-action or long-acting tablets or capsules must be swallowed whole and must not be crushed. Do not suddenly stop taking this drug without talking to your doctor. If you miss a dose, take it as soon as you remember but not if it is within 8 hours of the next dose. If it is within 8 hours,
skip the missed dose and resume your usual dosing schedule. Do not take two doses at one time to catch up. Count your number of heartbeats per one minute each morning. If your number of heartbeats in one minute is less than 60, call your doctor to check if you should take your medicine.

Side Effects:

This medicine may make you feel dizzy or faint, especially if you get up quickly after sitting or lying down. Swelling of hands and feet may occur. You may experience fatigue, constipation or dry mouth.

  • Call your doctor if:
  • You develop hives, itching, rash.
  • You develop severe dizziness.
  • You develop severe nausea.
  • You develop irregular heartbeat.
  • You develop swelling of feet or lower legs, or unexplained weight gain.
  • You develop chest pain.

Other changes may occur when using these medications. If you have questions about these changes, call your doctor or pharmacist.

Food and Drug Interactions:

Check with your pharmacist or doctor before taking any over-the-counter cough, cold, allergy, or diet drugs. Tell them about any other drugs you are taking. Ask them to check for any drug interactions. Avoid grapefruit juice if taking felodipine, nifedipine, verapamil, amlodipine.

Calcium Channel Blockers for High Blood Pressure

What To Think About

Your doctor may ask you to take your pulse regularly to make sure your heart rate is not too slow. To learn how to take your pulse, see the topic Taking a Pulse (Heart Rate) .

For tips on taking blood pressure medicine, see:

High Blood Pressure: Taking Medicines Properly.

Taking medicine

Medicine is one of the many tools your doctor has to treat a health problem. Taking medicine as your doctor suggests will improve your health and may prevent future problems. If you don’t take your medicines properly, you may be putting your health (and perhaps your life) at risk.

There are many reasons why people have trouble taking their medicine. But in most cases, there is something you can do. For suggestions on how to work around common problems, see the topic Taking Medicines as Prescribed.

Advice for women

If you are pregnant, breastfeeding, or trying to get pregnant, do not use any medicines unless your doctor tells you to. Some medicines can harm your baby. This includes prescription and over-the-counter medicines, vitamins, herbs, and supplements. And make sure that all your doctors know that you are pregnant, breastfeeding, or planning to get pregnant.


Follow-up care is a key part of your treatment and safety. Be sure to make and go to all appointments. And call your doctor if you are having problems. It’s also a good idea to know your test results and keep a list of the medicines you take.

Complete the new medication information form (PDF) ( What is a PDF document? ) to help you understand this medication.

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