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Diltiazem Hydrochloride XR Side Effects

Generic name: diltiazem

Medically reviewed by Last updated on Dec 13, 2023.

Note: This document contains side effect information about diltiazem. Some dosage forms listed on this page may not apply to the brand name Diltiazem Hydrochloride XR.

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:

Serious side effects

Along with its needed effects, diltiazem (the active ingredient contained in Diltiazem Hydrochloride XR) 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

Less common

Incidence not known

Other side effects

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

Less common

Incidence not known

For Healthcare Professionals

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.[Ref]


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)[Ref]

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.[Ref]


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

Frequency not reported: Thirst, tinnitus[Ref]


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[Ref]


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.[Ref]

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[Ref]


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

Frequency not reported: Dyspnea, epistaxis

Postmarketing reports: Asthma aggravation, bronchospasm[Ref]

Nervous system

Dizziness occurred more frequently with higher doses.[Ref]

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

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


Common (1% to 10%): Myalgia

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


Common (1% to 10%): Gout

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


Common (1% to 10%): Impotence

Frequency not reported: Albuminuria, crystalluria, nocturia, polyuria, sexual difficulties[Ref]


Common (1% to 10%): Conjunctivitis

Frequency not reported: Amblyopia, eye irritation, periorbital edema, retinopathy[Ref]


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


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

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


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

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

Frequency not reported: Clinical hepatitis/hepatitis[Ref]


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

Postmarketing reports: Purpura[Ref]


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


Frequency not reported: Gynecomastia[Ref]


1. (2002) "Product Information. Cardizem (diltiazem)." Hoechst Marion Roussel

2. Cerner Multum, Inc. "UK Summary of Product Characteristics."

3. Cerner Multum, Inc. "Australian Product Information."

4. (2011) "Product Information. Dilacor XR (diltiazem)." Aventis Pharmaceuticals

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Some side effects may not be reported. You may report them to the FDA.