Diltiazem - Precautions | Effects

Diltiazem is a well known drug from the group of calcium channel blockers. Diltiazem expands blood vessels which helps control high blood pressure. Diltiazem is used for the treatment of hypertension (high blood pressure) and ischemic heart disease. Some studies have shown that Diltiazem is effective in calcinosis treatment.1 This drug affects calcium movement into the heart, which causes expanding of blood vessels, thus improving supplying of oxygen to the heart muscle. All these effects help your heart to work easier with much less effort.


First of all, you need to know what medicine you have to avoid while on Diltiazem therapy. Here are some of the drugs you should never take concurrently with Diltiazem:

  • nifedipine,
  • nicardipine,
  • nimodipine,
  • amlodipine,
  • felodipine,
  • verapamil (Izopamil) and others.

Patients with atrioventricular block (AV block), especially patients with AV block second or third degree, should not use Diltiazem. This medicine can slow your heart rate down and may cause heart failure in these patients.

Patients with cardiogenic shock should avoid taking Diltiazem.

This drug should not be used in patients with heart rate lower than 60 beats/min (bradycardia).

If you have hepatic impairment, renal impairment, or you suffer from depression, you cannot use this drug.

Do not take any alcoholic beverages while taking Diltiazem, because you are more likely to experience adverse effects.

It is very important to check blood pressure regularly, even if you feel well and healthy. High blood pressure cause no symptoms. However, it can lead to heart attack and stroke, which is why it is important to keep your blood pressure within normal range.

You have to change lifestyle and eating habits in order to get all benefits from the therapy, such as:

  • Avoid stress
  • Stop smoking
  • Exercise at least 5 hours a week
  • Avoid heavy, spicy and fatty meals

Diltiazem use in pregnant woman and during lactation

There is little data about its safety during pregnancy. It acts as tocolytic which means that it may speed up your labor. Some studies have shown that it is effective in the treatment of arrhythmia in pregnant woman. Also, it is considered as effective treatment for chronic renal disease in pregnant woman because it preserves renal function and structure.2

Diltiazem is excreted into breast milk in small quantities which may lead to adverse effects. Avoid to breastfeed your baby while taking Diltiazem.

Diltiazem dosage

The usual dose of Diltiazem for the treatment of hypertension is 90 mg twice daily (every 12 hours). The dose can be increased to 360 mg daily.

The usual dose to treat angina pectoris is 90 mg two or three times a day. The dose of Diltiazem in the treatment of unstable angina can be increased to 480 mg daily.

Your doctor will determine what dose is suitable for you.

It is necessary to reduce the dose in patients older than 65 years. Patients with liver disorders also require dose reduction.

There is no data about using of Diltiazem in children.

Medicines that you should not take with Diltiazem

Following medicines should be avoided while taking Diltiazem:

  • Dantrolene, a drug used to treat of muscle spasms and malignant hyperthermia (malignant hyperpyreksia).
  • Antiarrhythmics (e.g. amiodarone).
  • Beta-blockers (cardiac medicines), such as:
    • bisoprolol,
    • metoprolol,
    • atenolol,
    • propranolol,
    • nebivolol and others. If taken concurrently with Diltiazem these drugs can decrease heartbeat which may lead to heart failure.
  • Medicines for hypertension treatment so-called alpha blockers:
    • prazosin,
    • terazosin,
    • doxazosin and others.
  • Medications for the treatment of angina pectoris, such as:
    • isosorbide dinitrate,
    • pentaerithrityl tetranitrate,
    • isosorbide mononitrate,
    • glycerol trinitrate (nitroglycerin) and others.
  • Medicines used to lower cholesterol levels in the blood, so-called statins, such as:
    • simvastatin,
    • rosuvastatin,
    • pravastatin,
    • atorvastatin,
    • lovastatin,
    • fluvastatin and others.
  • Drugs used to reduce inflammatory processes in the body, so-called corticosteroids, such as:
    • prednisolone,
    • methyl prednisolone and others.
  • Antiepileptic medications
  • Antibiotics, such as:
    • azithromycin,
    • clarithromycin,
  • Benzodiazepines (tranquilizers)

Side effects

Possible adverse effects of Diltiazem include:

  1. Gingival enlargement3
  2. Skin peeling
  3. Weight gain
  4. Allergic reaction
  5. Digestive disorders
  6. Eye irritation
  7. Bradycardia
  8. Nervousness
  9. Flushing
  10. Hyperglycemia
  11. Gynecomastia

Sawai has shown in his study that Diltiazem is safe to use even for longer periods to treat high blood pressure.4

Go to your doctor if you notice any side effects.


  1. Palmieri GM and others. Treatment of calcinosis with diltiazem. Arthritis Rheum. 1995: 38 (11): 1646-1654.
  2. Khanndelwal M, and others. Role of diltiazem in pregnant women with chronic renal disease. J Matern Fet. 2002: 12 (6): 408-412.
  3. Fattore L, and others. Gingival hyperplasia: a side effect of nifedipine and diltiazem. Spec Care Dent. 1991: 11 (3): 107-109.
  4. Swai K. Effects of long-term administration of diltiazem hydrochloride in hypertensive patients. Clin Ther. 1983: 5 (4): 422-435.

Information on this website are provided for educational purposes only and are not intended for medical advice, diagnosis or treatment.

If you have any concerns or questions about your health, you should always consult with a physician or other health-care professional.