Calan SR

Last updated on RxList: 6/2/2021
Calan SR Side Effects Center

What Is Calan?

Calan SR (verapamil hydrochloride) is a calcium ion antagonist used to treat hypertension (high blood pressure).

What Are Side Effects of Calan SR?

Calan SR is available in generic form. Common side effects of Calan SR include:

Dosage for Calan SR

The initial dose of Calan SR is 180 mg, given in the morning.

What Drugs, Substances, or Supplements Interact with Calan SR?

Calan SR may interact with

  • simvastatin,
  • atorvastatin,
  • beta-blockers,
  • digitalis,
  • vasodilators,
  • angiotensin-converting enzyme (ACE) inhibitors,
  • diuretics,
  • disopyramide,
  • flecainide,
  • quinidine,
  • alcohol,
  • lithium,
  • carbamazepine,
  • rifampin,
  • phenobarbital,
  • cyclosporine,
  • theophylline,
  • inhalation anesthetics,
  • neuromuscular blocking agents,
  • telithromycin, and
  • clonidine

Tell your doctor all medications and supplements you use.

Calan SR During Pregnancy and Breastfeeding

During pregnancy, Calan SR should be used only if prescribed. Calan SR passes into breast milk. Breastfeeding is not recommended while using Calan SR.

Additional Information

Our Calan SR (verapamil hydrochloride) Side Effects Drug Center provides a comprehensive view of available drug information on the potential side effects when taking this medication.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.


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Calan SR Consumer Information

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Get emergency medical help if you have signs of an allergic reaction: hives; difficult breathing; swelling of your face, lips, tongue, or throat.

Call your doctor at once if you have:

  • chest pain, fast or slow heart rate;
  • a light-headed feeling, like you might pass out;
  • shortness of breath (even with mild exertion), swelling, rapid weight gain;
  • fever, upper stomach pain, not feeling well; or
  • lung problems--anxiety, sweating, pale skin, wheezing, gasping for breath, cough with foamy mucus.

Common side effects may include:

  • nausea, constipation;
  • headache, dizziness; or
  • low blood pressure.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

Read the entire detailed patient monograph for Calan SR (Verapamil Hydrochloride Sustained-Release Oral Caplets)


Salt and sodium are the same. See Answer
Calan SR Professional Information


Serious adverse reactions are uncommon when verapamil therapy is initiated with upward dose titration within the recommended single and total daily dose. See WARNINGS for discussion of heart failure, hypotension, elevated liver enzymes, AV block, and rapid ventricular response. Reversible (upon discontinuation of verapamil) non-obstructive, paralytic ileus has been infrequently reported in association with the use of verapamil. The following reactions to orally administered verapamil occurred at rates greater than 1.0% or occurred at lower rates but appeared clearly drug-related in clinical trials in 4,954 patients:

Constipation 7.3% Dyspnea 1.4%
Dizziness 3.3% Bradycardia
Nausea 2.7% (HR <50/min) 1.4%
Hypotension 2.5% AV block
Headache 2.2% (total 1°, 2°, 3°) 1.2%
Edema 1.9% (2° and 3°) 0.8%
CHF, Pulmonary edema 1.8% Rash 1.2%
Fatigue 1.7% Flushing 0.6%

Elevated liver enzymes (see WARNINGS)

In clinical trials related to the control of ventricular response in digitalized patients who had atrial fibrillation or flutter, ventricular rates below 50/min at rest occurred in 15% of patients and asymptomatic hypotension occurred in 5% of patients.

The following reactions, reported in 1% or less of patients, occurred under conditions (open trials, marketing experience) where a causal relationship is uncertain; they are listed to alert the physician to a possible relationship:

Cardiovascular: angina pectoris, atrioventricular dissociation, chest pain, claudication, myocardial infarction, palpitations, purpura (vasculitis), syncope.

Digestive system: diarrhea, dry mouth, gastrointestinal distress, gingival hyperplasia.

Hemic and lymphatic: ecchymosis or bruising.

Nervous system: cerebrovascular accident, confusion, equilibrium disorders, insomnia, muscle cramps, paresthesia, psychotic symptoms, shakiness, somnolence.

Skin: arthralgia and rash, exanthema, hair loss, hyperkeratosis, macules, sweating, urticaria, Stevens-Johnson syndrome, erythema multiforme.

Special senses: blurred vision, tinnitus.

Urogenital: gynecomastia, galactorrhea/hyperprolactinemia, increased urination, spotty menstruation, impotence.

Treatment Of Acute Cardiovascular Adverse Reactions

The frequency of cardiovascular adverse reactions that require therapy is rare; hence, experience with their treatment is limited. Whenever severe hypotension or complete AV block occurs following oral administration of verapamil, the appropriate emergency measures should be applied immediately; eg, intravenously administered norepinephrine bitartrate, atropine sulfate, isoproterenol HCl (all in the usual doses), or calcium gluconate (10% solution). In patients with hypertrophic cardiomyopathy (IHSS), alpha-adrenergic agents (phenylephrine HCl, metaraminol bitartrate, or methoxamine HCl) should be used to maintain blood pressure, and isoproterenol and norepinephrine should be avoided. If further support is necessary, dopamine HCl or dobutamine HCl may be administered. Actual treatment and dosage should depend on the severity of the clinical situation and the judgment and experience of the treating physician.

Read the entire FDA prescribing information for Calan SR (Verapamil Hydrochloride Sustained-Release Oral Caplets)

© Calan SR Patient Information is supplied by Cerner Multum, Inc. and Calan SR Consumer information is supplied by First Databank, Inc., used under license and subject to their respective copyrights.

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