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Calan Side Effects

Generic Name: verapamil

Note: This page contains information about the side effects of verapamil. Some of the dosage forms included on this document may not apply to the brand name Calan.

In Summary

Common side effects of Calan include: sinus bradycardia. Other side effects include: pulmonary edema, severe hypotension, and second degree atrioventricular block. See below for a comprehensive list of adverse effects.

For the Consumer

Applies to verapamil: oral capsule extended release, oral capsule extended release 24 hr, oral tablet, oral tablet extended release, oral tablet extended release 24 hr

Other dosage forms:

In addition to its needed effects, some unwanted effects may be caused by verapamil (the active ingredient contained in Calan). In the event that any of these side effects do occur, they may require medical attention.

Major Side Effects

You should check with your doctor immediately if any of these side effects occur when taking verapamil:

Less common:
  • Blue lips and fingernails
  • blurred vision
  • burning, crawling, itching, numbness, prickling, "pins and needles", or tingling feelings
  • chest pain
  • confusion
  • coughing that sometimes produces a pink frothy sputum
  • difficult, fast, noisy breathing, sometimes with wheezing
  • dizziness, faintness, or lightheadedness when getting up from a lying or sitting position suddenly
  • increased sweating
  • lightheadedness, dizziness, or fainting
  • pale skin
  • shortness of breath
  • slow or irregular heartbeat
  • sore throat
  • sweating
  • swelling in legs and ankles
  • unusual tiredness or weakness
  • Chills
  • cold sweats
  • feeling of warmth
  • redness of the face, neck, arms and occasionally, upper chest

Minor Side Effects

Some of the side effects that can occur with verapamil may not need medical attention. As your body adjusts to the medicine during treatment these side effects may go away. Your health care professional may also be able to tell you about ways to reduce or prevent some of these side effects. If any of the following side effects continue, are bothersome or if you have any questions about them, check with your health care professional:

More common:
  • Difficulty having a bowel movement (stool)
  • headache
Less common:
  • Acid or sour stomach
  • belching
  • difficulty in moving
  • heartburn
  • indigestion
  • joint pain
  • muscle aching or cramping
  • muscle pains or stiffness
  • nausea
  • rash
  • stomach discomfort, upset, or pain
  • trouble sleeping
  • unusual drowsiness, dullness, tiredness, weakness, or feeling of sluggishness
  • swollen joints

For Healthcare Professionals

Applies to verapamil: compounding powder, intravenous solution, oral capsule extended release, oral tablet, oral tablet extended release


The most commonly reported side effects include constipation, dizziness, and headache.[Ref]

Nervous system

Seizures occurred rarely with IV administration.

Paralysis/tetraparesis was reported in a patient taking this drug and colchicine concurrently.[Ref]

Very common (10% or more): Headache (up to 12.1%)
Common (1% to 10%): Dizziness, lethargy
Rare (0.01% to 0.1%): Seizures
Frequency not reported: Rotary nystagmus, sleepiness, vertigo, lightheadedness, tingling, numbness, neuropathy
Postmarketing reports: Syncope, cerebrovascular accident, equilibrium disorders, parkinsonism/extrapyramidal symptoms/syndrome, paresthesia, shakiness/tremor, paralysis/tetraparesis, somnolence[Ref]


Cardiovascular side effects may occur with greater intensity at higher doses or in patients with a history of myocardial damage.

Approximately 15% of patients who had atrial flutter/fibrillation and received this drug and digoxin developed resting ventricular rates below 50 beats/min; in the same trial, asymptomatic hypotension occurred in approximately 5% of patients.

Asystole occurred after second/third degree AV block and was usually short in duration, with spontaneous cardiac action returning within seconds in the form of a sinus rhythm.[Ref]

Common (1% to 10%): Symptomatic hypotension/hypotension/abrupt blood pressure fall, sinus bradycardia/bradycardia (heart rate less than 50 beats/minute), severe tachycardia, ankle edema/edema, development/aggravation of congestive heart failure (CHF), atrioventricular (AV) block, peripheral edema
Uncommon (0.1% to 1%): Second-/third-degree AV block, palpitations, orthostasis
Postmarketing reports: Angina pectoris/chest pain, AV dissociation, ECG abnormal, claudication, hypertension, myocardial infarction, sinus arrest with asystole, decreased myocardial contractility, cardiogenic shock, bradyarrhythmia in atrial fibrillation, vasculitis, erythromelalgia[Ref]


Non-obstructive paralytic ileus was reversible when treatment was stopped.

Gingival hyperplasia occurred when this drug was given over a prolonged period of time, and was reversible once the drug was discontinued.[Ref]

Common (1% to 10%): Constipation, dyspepsia, nausea, diarrhea, flatulence
Uncommon (0.1% to 1%): Abdominal discomfort/pain
Frequency not reported: Non-obstructive paralytic ileus/ileus, bloating
Postmarketing reports: Dry mouth, gastrointestinal stress, gingival hyperplasia, vomiting[Ref]


Bronchospasm and laryngeal spasm occurred during hypersensitivity reactions.[Ref]

Common (1% to 10%): Pulmonary edema, pharyngitis, sinusitis, rhinitis, dyspnea
Rare (0.01% to 0.1%): Broncho/laryngeal spasm[Ref]


Common (1% to 10%): Fatigue, tiredness/malaise, accidental injury, pain
Frequency not reported: Infection, flu syndrome
Postmarketing reports: Tinnitus, asthenia[Ref]


Common (1% to 10%): Scalp irritation, rash
Uncommon (0.1% to 1%): Itching, urticaria, flushing, exanthema
Frequency not reported: Diaphoresis, photodermatitis
Postmarketing reports: Ecchymosis, bruising, alopecia/hair loss, hyperkeratosis, macules, Stevens-Johnson syndrome, hyperhidrosis/sweating, erythema multiforme, Quincke's edema/angioneurotic edema[Ref]

Itch and urticaria occurred in hypersensitivity reactions.[Ref]


Common (1% to 10%): Sleep disturbance
Uncommon (0.1% to 1%): Bad dreams, depression/emotional depression
Postmarketing reports: Confusion, psychotic symptoms, insomnia, nervousness[Ref]


Common (1% to 10%): Myalgia
Frequency not reported: Muscle fatigue
Postmarketing reports: Muscle cramps, arthralgia[Ref]


Reversible elevations liver enzymes occurred during treatment, and are likely the result of a hypersensitivity reaction (e.g., allergic hepatitis).[Ref]

Uncommon (0.1% to 1%): Elevated liver enzymes (transaminases, alkaline phosphatase)[Ref]


Rare (0.01% to 0.1%): Hypersensitivity/allergic reactions
Postmarketing reports: Allergy aggravated[Ref]


Frequency not reported: Lowered glucose tolerance
Postmarketing reports: Hyperkalemia[Ref]


Postmarketing reports: Galactorrhea, increased blood prolactin/hyperprolactinemia, increased urination, spotty menstruation, erectile dysfunction/impotence[Ref]


Postmarketing reports: Renal failure[Ref]


Gynecomastia occurred in older male patients on prolonged treatment, and was reversible upon discontinuation of this drug.[Ref]

Postmarketing reports: Gynecomastia[Ref]


Postmarketing reports: Purpura[Ref]


Postmarketing reports: Blurred vision[Ref]


1. "Product Information. Verelan PM (verapamil)." Schwarz Pharma, Mequon, WI.

2. Cerner Multum, Inc. "Australian Product Information." O 0

3. Cerner Multum, Inc. "UK Summary of Product Characteristics." O 0

4. "Product Information. Covera-HS (verapamil)." Searle, Skokie, IL.

5. "Product Information. Calan (verapamil)." Searle, Skokie, IL.

6. "Product Information. Isoptin (verapamil)." Knoll Pharmaceutical Company, Whippany, NJ.

Not all side effects for Calan may be reported. You should always consult a doctor or healthcare professional for medical advice. Side effects can be reported to the FDA here.

Disclaimer: Every effort has been made to ensure that the information provided is accurate, up-to-date and complete, but no guarantee is made to that effect. In addition, the drug information contained herein may be time sensitive and should not be utilized as a reference resource beyond the date hereof. This material does not endorse drugs, diagnose patients, or recommend therapy. This information is a reference resource designed as supplement to, and not a substitute for, the expertise, skill , knowledge, and judgement of healthcare practitioners in patient care. The absence of a warning for a given drug or combination thereof in no way should be construed to indicate safety, effectiveness, or appropriateness for any given patient. does not assume any responsibility for any aspect of healthcare administered with the aid of materials provided. The information contained herein is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. If you have questions about the substances you are taking, check with your doctor, nurse, or pharmacist.