Calcium channel blockers

Calcium channel blockers are medications that are prescribed to help lower blood pressure and treat chest pain associated with angina pectoris, also known as angina. 

  1. Treat hypertension.
  2. May also be prescribed to treat angina.
  3. Usually prescribed to people over 55 or from an African or Caribbean background. 

If you have any concerns relating to the conditions mentioned above, you can speak with one of our GPhC-registered clinicians via our online video consultation service. They are available from 9.30am-4.30pm, Monday to Friday. 

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Product information

What are calcium channel blockers?

Calcium channel blockers are drugs that are typically prescribed to treat high blood pressure (hypertension) and to manage symptoms of pain related to angina. They work by widening the arteries, allowing blood to flow more freely and reducing pressure.

What is hypertension?

Hypertension is high blood pressure, and is one of the most common conditions in the UK. Because it does not present with any symptoms, it’s thought that as many as a third of the population has it, with many people unaware of its risks. While it presents no dangers in itself, it can lead to serious health conditions, and in many cases requires treatment or lifestyle changes to help manage it.

Blood pressure is measured using two numbers: systolic (the force with which blood is pumped) and diastolic (the resistance to that force within the blood vessels). Normal or healthy blood pressure should read between 90/60mmHg and 120/mmHg. People who experience numbers in excess of 140mmHg/90mmHg (150/90mmHg for the over 80s) are considered to have hypertension. 

You can have your blood pressure checked at your local doctor’s surgery for free, as well as at many pharmacies and even some workplaces. It is recommended that you have your blood pressure regularly, and at least every five years, if you are over 40. 

Risks of hypertension include heart attacks, strokes, kidney disease, vascular dementia, heart failure, aortic aneurysms and peripheral arterial disease. Lowering your blood pressure even a fraction can significantly reduce the risks associated with these conditions.

What causes hypertension? 

Causes of hypertension may not always be obvious, but there are certain risk factors that are likely to play a role in the vast majority of cases. These include being of African or Caribbean origin or over 65 years of age, obesity, having a relative with the condition, smoking, eating too much salt, having an unhealthy diet low in fruits and vegetables, poor sleep, consuming too much caffeine or alcohol and not getting enough exercise.

How is hypertension treated?

Treatment for hypertension starts with making simple lifestyle changes. These can have a major effect on your overall health, as well as leading to a reduction in blood pressure levels without the need for medication. Lifestyle changes include quitting smoking, cutting down on caffeine, alcohol and salt, getting regular exercise (even if it’s only a brisk walk every day) and losing weight. 

There are many medications available for hypertension, each with its own advantages and disadvantages. For example, ACE inhibitors are one of the most commonly prescribed medications for people under the age of 55, while calcium blockers are more likely to be prescribed for people over the age of 55 or who are from African or Caribbean backgrounds. Angiotensin-2 receptor blockers (ARBs) are usually recommended for people who are unable to tolerate ace inhibitors. Other medications include beta blockers (which slow down the heart rate) and diuretics (which are prescribed in cases where calcium blockers cause issues).

What is angina?

Angina is a pain in the chest that is caused by a reduction of the flow of blood to the heart. Stable angina is described as a pain that occurs after exercise that subsides once you are at rest, as opposed to unstable angina, which can occur at any time and does not recede when you are resting.

What symptoms can angina cause? 

Symptoms of angina include a tight, dull or heavy pain that spreads from the chest to the neck, jaw, left arm and back. In some cases, it may also present with shortness of breath, nausea, fatigue and stomach discomfort. If it is the first time you have experienced these symptoms, it is important that you seek medical attention immediately if the symptoms do not pass when resting as it can be a sign that you are having a heart attack. It is recommended that you chew an aspirin while you wait for the ambulance to arrive. 

If you have already been diagnosed with angina, you should use the medication you have been prescribed and rest for a few minutes. If the symptoms do not pass you should call an ambulance.

How is angina treated? 

Glyceryl trinitrate (GTN) is a treatment that’s typically used when someone is experiencing an angina attack, as it reduces the risk of a heart attack occurring. It’s available as a spray or as a tablet that can be dissolved on the tongue. 

There are two treatments that can be used to help prevent angina symptoms: beta blockers and calcium channel blockers. Beta blockers slow down the heart rate, while calcium blockers relax blood vessels, allowing blood to be pumped around the body more easily. It’s possible that other medications may be considered if your risk of having a heart attack is high, such as statins or a low dose of aspirin. 

Surgery will only be considered if other treatments have proven ineffective. Surgical procedures include a coronary artery bypass graft (where a blood vessel from another part of the body is grafted to reroute blood flow past the affected area) and percutaneous coronary intervention (where the problematic artery is widened using a stent). 

If you would like to discuss calcium channel blockers or any related conditions with a GMC-registered clinician, our online video consultation service is available from 9.30am-4.30pm, five days a week. Our clinicians can also issue referrals to specialists for treatment and fit notes, where suitable.  

Page last reviewed:  01/07/2020
Side effects and warnings

What side effects can calcium channel blockers cause?

As with any medication, calcium channel blockers can cause side effects, so it is important that you understand what these are before starting treatment. If you are unsure, you should speak to your prescribing clinician, or read the patient information leaflet that comes with your medication.

The following information relates to the calcium channel blocker, amlodipine besilate, and may not apply to your specific treatment.  

If you experience any of the following side effects you should discontinue using amlodipine besilate and seek immediate medical assistance: wheezing, chest pain, shortness of breath, swelling of the eyelids, face, lips tongue or throat, skin reactions, severe itching, inflammation of the mucous membranes, toxic epidermal necrolysis, heart attack, irregular heartbeat, inflamed pancreas and abdominal and back pain.

Other side effects include: 

Very common (may affect more than 1 in 10 people): fluid retention. 

Common (may affect up to 1 in 10 people): headache, dizziness, sleepiness, palpitations, flushing, abdominal pain, nausea, diarrhoea, constipation, indigestion, tiredness, weakness, visual problems, cramps and swollen ankles. 

Uncommon (may affect up to 1 in 100 people): enlarged breasts in men, sleep disorders, irritability, depression, pain, feeling unwell, dry mouth, shaking, pins and needles, sweating, mood changes, anxiety, depression, trembling, taste abnormalities, numbness or tingling, loss of pain sensation, sneezing, runny nose, urine disorders, ringing or buzzing in the ears, fainting, increased heart rate, chest pain, aggravation of angina, low blood pressure, blood vessel inflammation, breathing difficulties, inflammation of the nasal mucosa, cough, being sick, diarrhoea, constipation, swollen gums, prickling and tingling sensations, itching, red patches on skin, nettle rash, hair loss, discolouration of the skin, cramps, back pain, muscle and joint pain, impotence and increases or decreases in weight. 

Rare (may affect up to 1 in 1,000 people): confusion.

Very rare (may affect up to 1 in 10,000 people): decreased white blood cell count, low blood platelets, hyperglycaemia, weakness, tingling, numbness, swelling of the gums, gastritis, abnormal liver function, hepatitis, jaundice, liver enzyme increases, increased muscle tension, blood vessel inflammation, sensitivity to light, rigidity, tremors and movement disorders. 

Are calcium channel blockers safe to use alongside other treatments?

All medications present a risk of interaction with other treatments that can make them unsuitable for use. It is therefore essential that you inform your prescribing clinician of any treatments you are currently or have recently taken so they can ensure that the medication being offered is safe for you to use. 

The following warnings relate to the calcium blocker amlodipine besilate. 

It’s particularly important that you inform your prescribing doctor if you are taking any of the following medications: verapamil, diltiazem, ketoconazole, itraconazole, ritonavir, clarithromycin, erythromycin telithromycin, rifampicin, rifabutin, nefazodone, St. John’s wort, dexamethasone, verapamil, diltiazem, dantrolene, tacrolimus, simvastatin, cyclosporine, phenobarbital, phenytoin, carbamazepine, ritonavir, indinavir, nelfinavir, nevirapine and sildenafil.

Please note that amlodipine may cause your blood pressure to drop too low if you are taking it alongside other hypertension medications.

Warnings and precautions when using calcium channel blockers

It is very important that you inform your prescribing clinician about any conditions you have or are prone to before starting treatment with calcium channel blockers so that they can be sure that this treatment is right for you. 

In the case of amlodipine besilate, if any of the following conditions apply to you, another treatment will need to be considered: allergies to any of its ingredients, cardiogenic shock, heart failure, unstable angina pectoris, pregnancy, breast-feeding and hypertension. 

Calcium channel blockers may not be suitable in the following conditions or circumstances: if you have a hypertensive crisis, liver problems and are under 18 years of age or elderly.

Are calcium channel blockers safe to use if you are pregnant or breastfeeding? 

It’s unclear if treatment with calcium channel blockers poses a risk to your baby, and therefore you should inform your prescribing clinician if you are pregnant, thinking of becoming pregnant or suspect you might be pregnant before starting treatment. Use of these medications is not recommended while breastfeeding as trace amounts can be passed on through breast milk.

What types of calcium channel blockers are available? 

While there are many different calcium channel medications, they essentially fall into two categories: dihydropyridine and non-dihydropyridine.

Dihydropyridine calcium channel blockers, which include amlodipine and felodipine, are drugs that widen the arteries, allowing blood to flow more freely. They are typically prescribed to treat angina, Reynaud’s syndrome and hypertension. 

Non-dihydropyridine calcium channel blockers also widen the arteries, reducing how hard the heart needs to work. For this reason, they are often referred to as “rate limiting calcium channel blockers”. They are typically prescribed to treat angina, hypertension and arrhythmia. 

Page last reviewed:  01/07/2020
Questions and Answers

Will calcium channel blockers affect my ability to drive? 

It’s possible that your ability to drive will be affected by calcium channel blockers, as side effects can include dizziness and visual disturbances. These tend to be more apparent at the start of treatment or after an increase in dosage, and usually subside over time. You should therefore wait and see how this treatment affects you before operating any heavy machinery. 

If you are unsure, you should speak to your prescribing clinician. 

Are there any food or drink restrictions during treatment?

It depends on the calcium channel blocker you’re using, and therefore, you should read the patient information leaflet provided with your treatment carefully before starting to use the medication. Eating grapefruit or drinking grapefruit juice is not suitable in some cases.  

Can calcium channel blockers lead to allergic reactions?

There is always a risk of allergic reactions with medications, so it is important that you tell your prescribing clinician about any allergies you have. You can also refer to the patient information leaflet that comes with your treatment, which lists the ingredients of the medication in full.

Can I purchase calcium channel blockers over the counter?

No. Calcium channel blockers are a prescription-only treatment. 

How can I buy calcium channel blockers online? 

Our registered clinicians can discuss calcium channel blockers and any related conditions with you via our online video consultation service. You can book an appointment between 9.30am-4.30pm, Monday to Friday. Our clinicians can also issue referrals to specialists for treatment and fit notes, where appropriate.  

Page last reviewed:  01/07/2020

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