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Prescription Prescription Required FormationFormulation: 24H ER Tablet

Tiazac XC

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Prescription Prescription Required FormationFormulation: 24H ER Tablet

Diltiazem ER

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Tiazac XC is a prescription medication used to treat mild to moderate high blood pressure and chronic stable angina (chest pain). Diltiazem, the active ingredient in Tiazac belongs to a class of medications called calcium channel blockers.

Tiazac XC works by relaxing blood vessels and preventing chest pain (angina). It is available in a 24-hour tablet form and is typically taken once daily. Tiazac XC may be used in combination with beta-blockers in chronic stable angina in patients with normal ventricular function.

Use and Dosage

Tiazac XC comes in the form of a tablet, and it should be taken once a day as directed by a doctor. The tablet should be swallowed whole with a full glass of water and should not be crushed or chewed. Tiazac XC should be taken consistently, at the same time each day, and should not be abruptly discontinued without consulting a doctor. Patients should follow all instructions and dosage recommendations provided by their doctor or pharmacist.

The recommended dosage of Tiazac XC may vary depending on the medical condition being treated and the patient's individual needs. According to the search results, the usual recommended starting dose of diltiazem extended-release tablets such as Tiazac XC ranges from 180 mg daily to 240 mg daily for the treatment of high blood pressure. For the treatment of angina, the recommended dosage range is 120 mg to 180 mg once daily. The maximum antihypertensive effect is typically observed within 14 days of treatment. The maximum daily dose of Tiazac XC is 360 mg. Note that the dosage may be adjusted by a doctor based on individual patient needs. Patients should always follow the dosage instructions provided by their doctor or pharmacist.

Take Tiazac XC exactly as prescribed by your doctor. If you miss a dose, take it as soon as possible and continue with your regular schedule. If it is almost time for your next dose, skip the missed dose and continue with your regular dosing schedule. Do not take a double dose to make up for a missed one. If you are not sure what to do after missing a dose, contact your doctor or pharmacist for advice.

Side Effects

Common Side Effects of Tiazac XC (Diltiazem ER):

  • Dizziness or lightheadedness
  • Flushing
  • General feeling of being unwell
  • Headache
  • Heartburn
  • Nausea
  • Sore or red eyes
  • Vision changes

Serious Side Effects of Tiazac XC (Diltiazem ER):

  • Chest pain
  • Irregular or fast, pounding heartbeat
  • Low blood pressure (dizziness or lightheadedness when rising from a sitting or lying position)
  • Signs of depression (feeling sad, losing interest in things you used to enjoy, weight changes, changes in sleep habits, feelings of guilt or worthlessness, thoughts of suicide)
  • Signs of heart failure (e.g., shortness of breath, leg swelling, fatigue or excessive difficulty breathing with exercise)
  • Signs of liver problems (e.g., nausea, vomiting, diarrhea, loss of appetite, weight loss, yellowing of the skin or whites of the eyes, dark urine, pale stools)
  • Slow heartbeat
  • Swelling of ankles, feet, or lower legs
  • Symptoms of ear, nose, or throat infection (e.g., fever, sore throat, cough inflammation of the nose or throat)
  • Symptoms of high blood sugar (e.g., frequent urination, increased thirst, excessive eating, unexplained weight loss, poor wound healing, infections, fruity breath odour)
  • Unusual tiredness or weakness

Forms and Strength

Tiazac XC (Diltiazem ER) is available in the following forms and strength:

Tiazac XC: Extended-Release Tablet

  • 120 mg
  • 180 mg
  • 240 mg
  • 300 mg
  • 360 mg


  • Tiazac XC should not be used in patients who have acute myocardial infarction; second- or third-degree AV block, unless a functioning pacemaker is present; hypotension (systolic BP <90 mmHg); sick sinus syndrome; or atrial fibrillation or flutter with a coexisting accessory bypass tract (e.g., Wolff-Parkinson-White, Lown-Ganong-Levine syndromes).
  • Tiazac XC should be used with caution in patients with impaired hepatic function, heart failure, severe hypotension, acute porphyria, and impaired renal function.
  • Tiazac XC can cause negative inotropic effects and exacerbate heart failure.
  • Tiazac XC can cause dizziness and lightheadedness, which may affect the ability to drive or operate heavy machinery.
  • Patients taking Tiazac XC should avoid consuming grapefruit or grapefruit juice, as it may increase the plasma concentration of the drug and increase the risk of side effects.
  • Tiazac XC should be used with caution in patients with a history of allergic reactions to other calcium channel blockers or other medications, and appropriate monitoring should be performed.
  • Tiazac XC may interact with other medications, such as beta-blockers, digoxin, cyclosporine, and certain antibiotics. Patients should inform their doctor of all medications they are taking before starting Tiazac XC.
  • Tiazac XC may cause flushing and headache in some patients, which usually resolves within a few days of starting the medication.
  • Tiazac XC may cause constipation, which may be relieved with dietary changes or over-the-counter laxatives.
  • Tiazac XC should not be abruptly discontinued, as it may lead to rebound hypertension or angina.
  • Tiazac XC is not recommended for use during pregnancy or breastfeeding, and patients should consult their doctor before taking the medication if they are pregnant or breastfeeding.
  • Tiazac XC may cause mild elevations in liver enzymes, although severe hepatic dysfunction is rare.
  • Tiazac XC should be stored at room temperature, protected from moisture and light, and kept out of reach of children.

Frequently Asked Questions (FAQ)

Can I take other medications while taking Tiazac XC?

Certain medications, such as beta-blockers, digoxin, cyclosporine, and some antibiotics, may interact with Tiazac XC. Tell your doctor about all medications you are taking before starting Tiazac XC.

Is Tiazac XC safe for use during pregnancy?

Tiazac XC is not recommended for use during pregnancy or breastfeeding. Consult your doctor before taking Tiazac XC if you are pregnant or breastfeeding.

Can Tiazac XC be abruptly discontinued?

Tiazac XC should not be abruptly discontinued, as it may lead to rebound hypertension or angina. Follow your doctor's instructions on how to stop taking Tiazac XC if necessary.


Additional information

Generic name:

Diltiazem ER


24H ER Tablet


120mg, 180mg, 240mg, 300mg, 360mg

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Online Pharmacies Canada has provided information from third parties intended to increase awareness and does not contain all the information about Tiazac XC (Diltiazem ER). Talk to your doctor or other qualified medical practitioners for medical attention or advice, or if you have any concerns about Tiazac XC (Diltiazem ER).