More frequently reported side effects include: dizziness, edema, asthenia, headache, and vasodilation. See below for a comprehensive list of adverse effects.

Applies to diltiazem: oral capsule extended release, oral capsule extended release 12 hr, oral capsule extended release 24 hr, oral tablet, oral tablet extended release, oral tablet extended release 24 hr

Other dosage forms:

• intravenous powder for solution, intravenous solution

Along with its needed effects, diltiazem may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor immediately if any of the following side effects occur while taking diltiazem:

More common

• Body aches or pain
• congestion
• cough
• dryness or soreness of the throat
• fever
• hoarseness
• runny nose
• tender or swollen glands in the neck
• trouble swallowing
• voice changes

Less common

• Chest pain or discomfort
• chills
• diarrhea
• difficult or labored breathing
• feeling faint, dizzy, or lightheaded
• feeling of warmth or heat
• flushing or redness of the skin, especially on the face and neck
• general feeling of discomfort or illness
• headache
• joint pain
• loss of appetite
• muscle aches and pains
• nausea
• shivering
• slow or irregular heartbeat
• sweating
• swelling of the hands, ankles, feet, or lower legs
• tightness in the chest
• trouble sleeping
• unusual tiredness or weakness
• vomiting

Incidence not known

• Blistering, peeling, or loosening of the skin
• itching
• large, hive-like swelling on the face, eyelids, lips, tongue, throat, hands, legs, feet, or sex organs
• no heartbeat
• red skin lesions, often with a purple center
• red, irritated eyes
• sores, ulcers, or white spots in the mouth or on the lips

Some side effects of diltiazem may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects. Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

More common

• Sneezing
• stuffy nose

Less common

• Acid or sour stomach
• belching
• constipation
• continuing ringing or buzzing or other unexplained noise in the ears
• degenerative disease of the joint
• difficulty with moving
• hearing loss
• heartburn
• indigestion
• lack or loss of strength
• muscle aching or cramping
• muscle pains or stiffness
• pain or tenderness around the eyes and cheekbones
• rash
• stomach discomfort, upset, or pain
• swollen joints

Incidence not known

• Hair loss or thinning of the hair

Applies to diltiazem: compounding powder, intravenous powder for injection, intravenous solution, oral capsule extended release, oral tablet, oral tablet extended release

The most commonly reported side effects include edema, headache, and dizziness.

Very common (10% or more): Peripheral edema (up to 15%)

Common (1% to 10%): Arrhythmia (junctional rhythm/isorhythmic dissociation), asymptomatic/symptomatic hypotension, atrioventricular (AV) block (first/second/third degree), bradycardia, bundle branch block, ECG abnormality, edema, extrasystole/ventricular extrasystole, flushing, lower limb edema, palpitations, vasodilation

Uncommon (0.1% to 1%): Orthostatic hypotension

Frequency not reported: Angina, asystole/cardiac arrest, atrial flutter, chest pain, development/aggravation of congestive heart failure, hypotension, sinoatrial block, sinus node dysfunction, sinus pause/arrest, vasculitis, ventricular arrhythmia, ventricular fibrillation, ventricular tachycardia/tachycardia

Postmarketing reports: Myocardial infarction, vasodilation symptoms (flushing, lower limb edema, sweating)

A patient with Prinzmetal's angina developed asystole after a single, 60 mg dose.

Myocardial infarction was not readily distinguishable from the natural history of the disease.

Vasodilatory events (e.g., peripheral edema, headache, flushing) are dose-related and may be more common in elderly patients.

First degree AV block and sinus bradycardia occurred more frequently with higher doses.

Common (1% to 10%): Asthenia, fatigue, flu syndrome, infection, malaise, pain

Frequency not reported: Thirst, tinnitus

Common (1% to 10%): Abdominal enlargement, constipation, dyspepsia, gastric pain, nausea

Uncommon (0.1% to 1%): Diarrhea, vomiting

Rare (0.01% to 0.1%): Dry mouth

Frequency not reported: Gastrointestinal disorder, gingivitis, gingival hyperplasia

Well-documented cases of rashes (as leukocytoclastic vasculitis) have been reported, but a definitive between these events and this drug have not been established.

Lichenoid keratosis and hyperpigmentation occurred in skin exposed to the sun.

Common (1% to 10%): Erythema, hot flushes, rash, urticaria

Frequency not reported: Acute generalized exanthematous pustular dermatitis, desquamative erythema with/without fever exfoliative dermatitis, facial edema, hyperhidrosis/sweating, hyperpigmentation, leukocytoclastic vasculitis, petechiae, photosensitivity (lichenoid keratosis), pruritus, Steven-Johnson's syndrome

Postmarketing reports: Allergic dermatitis, alopecia, angioneurotic edema, erythema multiforme, generalized dermatitis, musculocutaneous reactions, simple erythema, toxic epidermal necrolysis

Common (1% to 10%): Bronchitis, cough, increased cough, pharyngitis, sinus/nasal congestion

Frequency not reported: Dyspnea, epistaxis

Postmarketing reports: Asthma aggravation, bronchospasm

Common (1% to 10%): Dizziness, headache, lightheadedness

Frequency not reported: Amnesia, dysgeusia, extrapyramidal syndrome/symptoms, gait abnormality, paresthesia, somnolence, syncope, tremor

Dizziness occurred more frequently with higher doses.

Common (1% to 10%): Myalgia

Frequency not reported: Creatine phosphokinase (CPK) increase, muscle cramp, muscle pain, muscle weakness, myopathy, neck rigidity, osteoarticular pain

Common (1% to 10%): Gout

Frequency not reported: Anorexia, hyperglycemia, hyperuricemia, mild elevation of alkaline phosphatase, mild elevation of lactate dehydrogenase, thirst, weight increase

Common (1% to 10%): Impotence

Frequency not reported: Albuminuria, crystalluria, nocturia, polyuria, sexual difficulties

Common (1% to 10%): Conjunctivitis

Frequency not reported: Amblyopia, eye irritation, periorbital edema, retinopathy

Common (1% to 10%): Injection site reactions (e.g., itching, burning)

Uncommon (0.1% to 1%): Insomnia, nervousness

Frequency not reported: Abnormal dreams, depression, hallucinations, mood changes (including depression), personality change

There were rare cases of clinical hepatitis that were reversible with discontinuation of this drug.

Uncommon (0.1% to 1%): Increased hepatic enzymes (ALT, AST)

Frequency not reported: Clinical hepatitis/hepatitis

Frequency not reported: Eosinophilia, hemolytic anemia, increased bleeding time, leukopenia, lymphadenopathy, thrombocytopenia

Postmarketing reports: Purpura

Frequency not reported: Allergic reactions, angioedema (including facial/periorbital edema)

Frequency not reported: Gynecomastia