Last updated on RxList: 1/20/2021
Calan Side Effects Center

What Is Calan?

Calan (verapamil hydrochloride) is a calcium channel blocker used to treat hypertension (high blood pressure), angina (chest pain), and certain heart rhythm disorders. Calan is available in generic form.

What Are Side Effects of Calan?

Common side effects of Calan include:

  • dizziness,
  • slow heartbeat,
  • constipation,
  • nausea,
  • headache,
  • tiredness,
  • skin rash or itching, or
  • flushing (warmth, itching, redness, or tingly feeling under your skin).

Tell your doctor if you have unlikely but serious side effects of Calan including:

  • swelling ankles or feet,
  • shortness of breath,
  • unusual tiredness,
  • unexplained or sudden weight gain,
  • severe dizziness,
  • fainting,
  • fast or very slow heartbeat,
  • fever, sore throat, and headache with a severe blistering, peeling, and red skin rash,
  • restless muscle movements in your eyes, tongue, jaw, or neck,
  • stomach pain,
  • loss of appetite,
  • dark urine,
  • clay-colored stools, or
  • yellowing of the skin or eyes (jaundice).

Dosage for Calan

The usual dose of Calan to treat angina is 80 mg to 120 mg three times a day. The dosage to treat arrhythmias ranges from 240 to 480 mg/day divided into three or four daily doses. The usual initial dosage to treat hypertension is 80 mg three times a day (240 mg/day).

What Drugs, Substances, or Supplements Interact with Calan?

Calan may interact with other blood pressure medications, buspirone, carbamazepine, cimetidine, cyclosporine, digoxin, lithium, lovastatin, phenobarbital, rifampin, theophylline, sedatives, antibiotics, antifungals, beta-blockers, heart rhythm medications, or HIV/AIDS medicine. Tell your doctor all medications you use.

Calan During Pregnancy and Breastfeeding

During pregnancy Calan should be used only when prescribed. This medication passes into breast milk but it is unlikely to harm a nursing infant. Consult your doctor before breastfeeding.

Additional Information

Our Calan (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 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 (Verapamil HCl)


In the U.S., 1 in every 4 deaths is caused by heart disease. See Answer
Calan Professional Information


Serious adverse reactions are uncommon when CALAN 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% CHF, Pulmonary edema 1.8%
Dizziness 3.3% Dyspnea 1.4%
Nausea 2.7% Bradycardia (HR <50/min) 1.4%
Hypotension 2.5% AV block total (1°, 2°, 3°) 1.2%
Headache 2.2% 2° and 3° 0.8%
Edema 1.9% 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 at rest occurred in 15% of patients and asymptomatic hypotension occurred in 5% of patients.

The following reactions, reported in 1.0% 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, extrapyramidal symptoms.

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 (Verapamil HCl)


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

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