Dilacor XR Side Effects Center

Last updated on RxList: 2/2/2022
Dilacor XR Side Effects Center

What Is Dilacor XR?

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

What Are Side Effects of Dilacor XR?

Common side effects of Dilacor XR include:

  • stuffy nose,
  • skin rash or itching,
  • dizziness,
  • headache,
  • tired feeling,
  • nausea,
  • upset stomach,
  • flushing (warmth, itching, redness, or tingly feeling under your skin),
  • weakness,
  • sore throat, or
  • cough

Dosage for Dilacor XR

Dosages of Dilacor XR are adjusted to each patient's needs. To treat hypertension the starting dose is 180 mg or 240 mg once daily. To treat angina, the starting dose is 120 mg once daily, which may be adjusted up to 480 mg once daily.

What Drugs, Substances, or Supplements Interact with Dilacor XR?

Dilacor XR may interact with amiodarone, buspirone, carbamazepine, cimetidine, cyclosporine, digoxin, lovastatin, rifampin, quinidine, sedatives, antibiotics, antifungals, beta-blockers, or HIV/AIDS medicines. Tell your doctor all medications and supplements you use.

Dilacor XR During Pregnancy or Breastfeeding

During pregnancy, Dilacor XR should be used only if prescribed. This drug passes into breast milk and may harm a nursing baby. Consult your doctor before breastfeeding.

Additional Information

Our Dilacor XR (diltiazem 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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Dilacor XR Consumer Information

Get emergency medical help if you have signs of an allergic reaction (hives, difficult breathing, swelling in your face or throat) or a severe skin reaction (fever, sore throat, burning eyes, skin pain, red or purple skin rash with blistering and peeling).

Call your doctor at once if you have:

  • chest pain;
  • slow heartbeats;
  • pounding heartbeats or fluttering in your chest;
  • a light-headed feeling, like you might pass out; or
  • heart problems--swelling, rapid weight gain, feeling short of breath.

Common side effects may include:

  • swelling;
  • dizziness, weakness;
  • headache;
  • nausea; or
  • rash.

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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Dilacor XR Professional Information


Serious adverse reactions to diltiazem hydrochloride have been rare in studies with other formulations, as well as with Dilacor XR®. It should be recognized, however, that patients with impaired ventricular function and cardiac conduction abnormalities have usually been excluded from these studies.


The most common adverse events (frequency ≥ 1%) in placebo-controlled, clinical hypertension studies with Dilacor XR using daily doses up to 540 mg, are listed in the table below with placebo-treated patients included for comparison.


Adverse Events (COSTART Term) Dilacor XR®*
# pts (%)
# pts (%)
rhinitis 29 (9.6) 7 (8.0)
headache 27 (8.9) 12 (13.8)
pharyngitis 17 (5.6) 4 (4.6)
constipation 11 (3.6) 2 (2.3)
cough increase 9 (3.0) 2 (2.3)
flu syndrome 7 (2.3) 1 (1.1)
edema, peripheral 7 (2.3) 0 (0.0)
myalgia 7 (2.3) 0 (0.0)
diarrhea 6 (2.0) 0 (0.0)
vomiting 6 (2.0) 0 (0.0)
sinusitis 6 (2.0) 1 (1.1)
asthenia 5 (1.7) 0 (0.0)
pain, back 5 (1.7) 2 (2.3)
nausea 5 (1.7) 1 (1.1)
dyspepsia 4 (1.3) 0 (0.0)
vasodilatation 4 (1.3) 0 (0.0)
injury, accident 4 (1.3) 0 (0.0)
pain, abdominal 3 (1.0) 0 (0.0)
arthrosis 3 (1.0) 0 (0.0)
insomnia 3 (1.0) 0 (0.0)
dyspnea 3 (1.0) 0 (0.0)
rash 3 (1.0) 1 (1.1)
tinnitus 3 (1.0) 0 (0.0)
*Adverse events occurring in 1% or more of patients receiving Dilacor XR.


The most common adverse events (frequency ≥ 1%) in a placebo-controlled, short-term (2 week) clinical angina study with Dilacor XR are listed in the table below with placebo-treated patients included for comparison. In this trial, following a placebo phase, patients were randomly assigned to once daily doses of either 120, 240, or 480 mg of Dilacor XR.


Adverse Events (COSTART Term) Dilacor XR®*
# pts (%)
# pts (%)
asthenia 5 (3.6) 2 (4.0)
headache 4 (2.9) 3 (6.0)
pain, back 4 (2.9) 1 (2.0)
rhinitis 4 (2.9) 1 (2.0)
constipation 3 (2.2) 1 (2.0)
nausea 3 (2.2) 0 (0.0)
edema, peripheral 3 (2.2) 1 (2.0)
dizziness 3 (2.2) 0 (0.0)
cough, increased 3 (2.2) 0 (0.0)
bradycardia 2 (1.4) 0 (0.0)
fibrillation, atrial 2 (1.4) 0 (0.0)
arthralgia 2 (1.4) 0 (0.0)
dream, abnormal 2 (1.4) 0 (0.0)
dyspnea 2 (1.4) 0 (0.0)
pharyngitis 2 (1.4) 1 (2.0)
*Adverse events occurring in 1% or more of patients receiving Dilacor XR.

Infrequent Adverse Events

The following additional events (COSTART Terms), listed by body system, were reported infrequently (less than 1%) in all subjects, hypertensive (n=425) or angina (n=318) patients who received Dilacor XR, or with other formulations of diltiazem.


Cardiovascular: First-degree AV block, arrhythmia, postural hypotension, tachycardia, pallor, palpitations, phlebitis, ECG abnormality, ST elevation.

Nervous System: Vertigo, hypertonia, paresthesia, dizziness, somnolence.

Digestive System: Dry mouth, anorexia, tooth disorder, eructation.

Skin and Appendages: Sweating, urticaria, skin hypertrophy (nevus).

Respiratory System: Epistaxis, bronchitis, respiratory disorder.

Urogenital System: Cystitis, kidney calculus, impotence, dysmenorrhea, vaginitis, prostate disease.

Metabolic and Nutritional Disorders: Gout, edema.

Musculoskeletal System: Arthralgia, bursitis, bone pain.

Hemic and Lymphatic System: Lymphadenopathy.

Body as a Whole: Pain, unevaluable reaction, neck pain, neck rigidity, fever, chest pain, malaise.

Special Senses: Amblyopia (blurred vision), ear pain.


Cardiovascular: Palpitations, AV block, sinus bradycardia, bigeminal extrasystole, angina pectoris, hypertension, hypotension, myocardial infarct, myocardial ischemia, syncope, vasodilatation, ventricular extrasystole.

Nervous System: Abnormal thinking, neuropathy, paresthesia.

Digestive System: Diarrhea, dyspepsia, vomiting, colitis, flatulence, GI hemorrhage, stomach ulcers.

Skin and Appendages: Contact dermatitis, pruritus, sweating.

Respiratory System: Respiratory distress.

Urogenital System: Kidney failure, pyelonephritis, urinary tract infection.

Metabolic and Nutritional Disorders: Weight increase.

Musculoskeletal System: Myalgia.

Body as a Whole: Chest pain, accidental injury, infection.

Special Senses: Eye hemorrhage, ophthalmitis, otitis media, taste perversion, tinnitus.

There have been post-marketing reports of Stevens-Johnson syndrome and toxic epidermal necrolysis associated with the use of diltiazem hydrochloride.

Read the entire FDA prescribing information for Dilacor XR (Diltiazem Hydrochloride Capsule, Extended Release)

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

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