Diltiazem is used to treat high blood pressure (hypertension) and prevent chest pain (angina). Lowering high blood pressure helps prevent strokes, heart attacks, and kidney problems. When used regularly, diltiazem can decrease the number and severity of episodes of chest pain from angina. It may help increase your ability to exercise.

Diltiazem is called a calcium channel blocker. It works by relaxing blood vessels in the body and heart so blood can flow more easily. Diltiazem also lowers your heart rate. These effects help the heart work less hard and lower blood pressure.

Take this medication by mouth with or without food, usually once daily or as directed by your doctor. Swallow the capsules whole. Do not crush or chew the capsules. Doing so can release all of the drug at once and may increase your risk of side effects.

Your doctor may gradually increase your dose. Follow your doctor's instructions carefully. The dosage is based on your medical condition, response to treatment, and other medications you may be taking. Be sure to tell your doctor and pharmacist about all the products you use (including prescription drugs, nonprescription drugs, and herbal products).

Use this medication regularly to get the most benefit from it. To help you remember, use it at the same time each day. It is important to continue taking this medication even if you feel well. Most people with high blood pressure do not feel sick. For the treatment of high blood pressure, it may take 2 to 4 weeks before you get the full benefit of this drug.

This medication must be taken regularly to prevent angina. It should not be used to treat angina when it occurs. Use other medications (such as nitroglycerin placed under the tongue) to relieve an angina attack as directed by your doctor. Consult your doctor or pharmacist for details.

Tell your doctor if your condition worsens (for example, your chest pain worsens or your routine blood pressure readings increase).

Before taking diltiazem, tell your doctor or pharmacist if you are allergic to it; or if you have any other allergies. This product may contain inactive ingredients, which can cause allergic reactions or other problems. Talk to your pharmacist for more details.

Before using this medication, tell your doctor or pharmacist your medical history, especially of: certain types of heart rhythm problems (such as sick sinus syndrome/atrioventricular block), liver disease, kidney disease, heart failure.

This drug may make you dizzy. Alcohol or marijuana (cannabis) can make you more dizzy. Do not drive, use machinery, or do anything that needs alertness until you can do it safely. Limit alcoholic beverages. Talk to your doctor if you are using marijuana (cannabis).

Before having surgery, tell your doctor or dentist that you are taking this medication.

Older adults may be more sensitive to the side effects of this drug, especially dizziness, constipation, or swelling ankles/feet.

This medication should be used only when clearly needed during pregnancy. Discuss the risks and benefits with your doctor.

This drug passes into breast milk and may have undesirable effects on a nursing infant. Consult your doctor before breast-feeding.

Dizziness, lightheadedness, weakness, nausea, flushing, constipation, and headache may occur. If any of these effects persist or worsen, tell your doctor or pharmacist promptly.

To lower the risk of dizziness and lightheadedness, get up slowly when rising from a sitting or lying position.

Remember that your doctor has prescribed this medication because he or she has judged that the benefit to you is greater than the risk of side effects. Many people using this medication do not have serious side effects.

Tell your doctor right away if you have any serious side effects, including: fainting, new or worsening symptoms of heart failure (such as shortness of breath, swelling ankles/feet, unusual tiredness, unusual/sudden weight gain), slow/irregular/pounding/fast heartbeat, mental/mood changes (such as depression, agitation), unusual dreams, severe stomach/abdominal pain, dark urine, persistent nausea/vomiting, yellowing eyes/skin.

A very serious allergic reaction to this drug is rare. However, get medical help right away if you notice any symptoms of a serious allergic reaction, including: rash, itching/swelling (especially of the face/tongue/throat), severe dizziness, trouble breathing.

This is not a complete list of possible side effects. If you notice other effects not listed above, contact your doctor or pharmacist.

How should I use this medicine?

Take this medicine by mouth with a glass of water. Follow the directions on the prescription label. Swallow whole, do not crush or chew. Ask your doctor or pharmacist if your should take this medicine with food. Take your doses at regular intervals. Do not take your medicine more often then directed. Do not stop taking except on the advice of your doctor or health care professional. Ask your doctor or health care professional how to gradually reduce the dose.

Talk to your pediatrician regarding the use of this medicine in children. Special care may be needed.

What if I miss a dose?

If you miss a dose, take it as soon as you can. If it is almost time for your next dose, take only that dose. Do not take double or extra doses.

What should I watch for while using this medicine?

Check your blood pressure and pulse rate regularly. Ask your doctor or health care professional what your blood pressure and pulse rate should be and when you should contact him or her.

You may feel dizzy or lightheaded. Do not drive, use machinery, or do anything that needs mental alertness until you know how this medicine affects you. To reduce the risk of dizzy or fainting spells, do not sit or stand up quickly, especially if you are an older patient. Alcohol can make you more dizzy or increase flushing and rapid heartbeats. Avoid alcoholic drinks.