See also Warning section.

Take this medication by mouth as directed by your doctor, usually once daily. This medication may be taken with or without food.

Do not crush or chew extended-release tablets. Doing so can release all of the drug at once, increasing the risk of side effects. Also, do not split extended-release tablets unless they have a score line and your doctor or pharmacist tells you to do so. Swallow the whole or split tablet without crushing or chewing.

To reduce your risk of side effects, your doctor may direct you to start this medication at a low dose and gradually increase your dose. Follow your doctor's instructions carefully. The dosage is based on your medical condition and response to treatment.

Use this medication regularly to get the most benefit from it. To help you remember, take it at the same time each day. Do not suddenly stop taking this medication without consulting your doctor. Your condition may become worse when the drug is suddenly stopped.

For the treatment of high blood pressure, it may take several weeks before you get the full benefit of this drug. Keep taking this medication even if you feel well. Most people with high blood pressure do not feel sick.

To prevent chest pain, a second heart attack, or migraine headaches, it is very important to take this medication regularly as prescribed. This drug should not be used to treat chest pain or migraines when they occur. Use other medications to relieve sudden attacks as directed by your doctor (for example, nitroglycerin tablets placed under the tongue for chest pain, "triptan" drugs such as sumatriptan for migraines). Consult your doctor or pharmacist for details.

Tell your doctor if your condition does not get better or if it gets worse (for example, your blood pressure readings remain high or increase, your chest pain or migraines occur more often).