Side Effects of Calcium Channel Blockers

Calcium channel blockers are medications commonly used to treat hypertension (high blood pressure), angina (chest pain) and arrhythmia (irregular heart beat). These medications should be taken with care as they can interact with other medications as well as cause side effects.

Types

There are two main types of calcium channel blockers. The first type targets the cells in the muscles of the heart. These medications, including verapamil and diltiazem, work to reduce how hard the heart has to work thereby relieving angina, arrhythmia and high blood pressure. The other type, known as dihydropyridines, targets the arteries helping them to relax and therefore lowering blood pressure. Even though these medications may act on different parts of the body both can induce side effects.

Function

Cells are permeable, meaning they allow substances into and out of the cell, including ions such as sodium and calcium. As calcium enters a muscle cell it triggers the muscle to contract. This is very important for normal functions such as the beating of the heart. However, if too much calcium enters the cells, the muscles can contract too often or too hard. Calcium channel blockers decrease the amount of calcium that can enter the cells and therefore reduces contractions. In the heart muscle this results in the heart working less hard and in the smooth muscles of arteries it results in the arteries becoming relaxed, or more open, decreasing blood pressure.

Drug Interactions

It is important to always discuss all medications you take with your doctor, especially when medications involve the function of the heart. Some medications can either increase or decrease the effect of the calcium channel blockers. Caution should be taken if you are currently taking other heart medications such as beta-blockers, ACE inhibitors, antiarrhythmics and digitalis. Other things that can influence the effects of calcium channel blockers include vitamin D, diuretics, corticosteroids, smoking and eating or drinking grapefruit.

Common Side Effects

Because calcium channel blockers can cause a rapid decrease in blood pressure, the most common side effect is dizziness. Be sure to always stand up slowly and do not drive until you know how your body will react to this medication. Other common side effects include headaches, constipation, fluid retention leading to swelling in the ankles or feet, flushing and heartburn.

Rare Side Effects

Taking calcium channel blockers may trigger other side effects including wheezing, coughing, shortness of breath, trouble swallowing and upset stomach. In rare cases these medications may cause chest pain, fainting, fever, swollen and bloody gums and rashes. If you experience any of these side effects, or if they persist or worsen, contact your doctor immediately.

References

• Texas Heart Institute
• The Mayo Clinic