Medically reviewed by Jessica Swirble, PharmD
Last updated on April 21, 2025
Drug Information | Side Effects | Use & Dosage | Request an Online Prescription
Diltiazem ER (extended-release) is a prescription medication used to treat high blood pressure (hypertension), chest pain (angina), and certain heart rhythm disorders.
Doctors prescribe diltiazem ER to treat several cardiovascular conditions, such as:
Diltiazem ER may be prescribed with other treatment strategies like lifestyle changes and other medications.
Diltiazem ER belongs to a class of drugs known as calcium channel blockers. It works by relaxing the muscles of your heart and blood vessels. By blocking calcium from entering the cells of the heart and arterial walls, diltiazem ER helps to lower blood pressure, reduce chest pain, and regulate heart rhythm.
Diltiazem ER is available as an extended-release oral capsule or tablet.
The dosage and frequency of use depend on the condition being treated, its severity, and how you respond to the medication.
Follow your healthcare provider's instructions regarding dosage and schedule. Do not exceed the prescribed dose or frequency of use without consulting your provider.
Diltiazem ER is used to manage hypertension, angina, and heart rhythm disorders. The effects can be noticeable within a few hours, but it may take several days to achieve the desired improvement in symptoms.
Continue using diltiazem ER as prescribed, even if you start feeling better. Regular use according to your prescription is crucial for the management of your condition.
While diltiazem ER is primarily used for treating hypertension, angina, and certain heart rhythm disorders, healthcare providers may prescribe it off-label for other conditions.
Discuss any alternative uses of diltiazem ER with your healthcare provider.
Diltiazem ER is available in the following dosage forms:
Diltiazem ER is a prescription medication. You must have a valid prescription from a licensed healthcare provider to obtain it.
The use of diltiazem ER can lead to various side effects in some individuals.
Common mild side effects of diltiazem ER use include:
More severe side effects of diltiazem ER use can include:
If you experience any severe or concerning side effects while taking diltiazem ER, contact your healthcare provider right away.
Inform your healthcare provider about any existing medical conditions, allergies, or other medications you are taking before starting treatment with diltiazem ER. This includes prescription drugs, over-the-counter medications, and dietary supplements, as they may interact with diltiazem ER.
Tell your provider if you are taking these medications or supplements:
You should also mention medical conditions such as:
If you are pregnant, planning to become pregnant, or breastfeeding, discuss the potential risks and benefits of using diltiazem ER with your healthcare provider.
Take diltiazem ER exactly as prescribed by your healthcare provider. Do not exceed the recommended dose or duration of treatment.
Your provider may direct you to avoid alcohol while taking diltiazem ER, as it can increase the risk of side effects.
Your provider may direct you to avoid grapefruit juice while taking diltiazem ER, as it can increase the risk of side effects.
Diltiazem ER can cause dizziness. Avoid driving or operating heavy machinery until you know how the medication affects you.
Complete the full course of treatment, even if you feel better, to ensure the medication's effectiveness in managing your condition.
In case of a diltiazem ER overdose, seek medical attention immediately. Symptoms of overdose may include severe dizziness, fainting, difficulty breathing, or an unusually slow or irregular heartbeat. If you suspect an overdose, contact the poison control helpline at 1-800-222-1222 or call emergency services.
Diltiazem ER is available in the following forms:
The typical starting dose of diltiazem ER varies depending on the condition being treated, the severity of symptoms, and individual patient factors. It is crucial to follow your healthcare provider's instructions regarding dosage and administration.
For hypertension:
For angina:
The dosage may be adjusted based on the response and tolerance to the medication. Your healthcare provider will determine the most appropriate dose based on your medical history and your response to the medication.
Diltiazem ER should be taken as prescribed by your healthcare provider. Do not exceed the recommended dose or duration of treatment without consulting your provider.
If you have any questions about your dosage or need adjustments, contact your healthcare provider for guidance. If you want to talk to a provider right away, consider scheduling an online doctor appointment through a telehealth platform like Sesame.
If you miss a dose of diltiazem ER, take it as soon as you remember unless it is close to the time for your next scheduled dose. In that case, skip the missed dose and continue your regular dosing schedule. Do not double the dose to make up for a missed one.
Take diltiazem ER around the same time daily to maintain a consistent amount of medication in your body.
Continue taking diltiazem ER as prescribed by your healthcare provider, even if you start feeling better. It's important to keep taking the medication as directed to manage your condition effectively.
Do not suddenly stop taking diltiazem ER; this can cause a return of your symptoms.
If you have any concerns or questions about your medication, discuss them with your healthcare provider for medical advice and recommendations.
Store diltiazem ER according to the instructions provided by your healthcare provider or pharmacist. Keep it at room temperature, away from light and moisture. Ensure the container is tightly closed and out of reach of children.
Do not use expired medication or medications that appear damaged or discolored. If you have any questions about storage, consult your healthcare provider or pharmacist for guidance.