Diltiazem is a non-dihydropyridine calcium channel blocker that relaxes coronary and peripheral arteries and slows conduction through the atrioventricular (AV) node. Clinically, it is used to treat hypertension (to lower blood pressure and reduce cardiovascular risk), chronic stable angina and vasospastic (Prinzmetal) angina (to reduce chest pain by improving coronary blood flow and decreasing myocardial oxygen demand), and to control ventricular rate in supraventricular tachyarrhythmias such as atrial fibrillation or atrial flutter. Its dual actions—vasodilation and rate control—make it a versatile option when beta-blockers are not tolerated or when additional rate reduction is needed.
In hypertension, diltiazem helps lower systolic and diastolic pressures, which supports long-term protection against stroke, heart attack, and kidney disease. For angina, patients often experience fewer episodes and improved exercise tolerance. In atrial fibrillation with rapid ventricular response, extended-release diltiazem is commonly used for sustained rate control; immediate-release formulations are sometimes used for short-term titration under medical supervision.
Diltiazem is available as immediate-release (IR) tablets taken multiple times per day and extended-release (ER/SR/XR) capsules or tablets designed for once-daily or twice-daily use. The choice depends on the condition being treated, patient preference, and response. Extended-release forms provide smoother 24-hour control of blood pressure or heart rate, while immediate-release products may be useful for flexible dose titration. Swallow ER capsules or tablets whole; do not crush or chew extended-release products unless your specific product information explicitly allows opening and sprinkling (follow the exact directions supplied with your brand).
For hypertension, clinicians typically start with a low-to-moderate dose of extended-release diltiazem and adjust every 1 to 2 weeks based on blood pressure, heart rate, and tolerance. For chronic angina, similar titration aims to minimize chest pain while maintaining appropriate resting heart rate and activity tolerance. In atrial fibrillation rate control, providers may initiate therapy with a conservative dose and up-titrate to achieve a target resting heart rate, often 60–100 bpm, while watching for bradycardia, hypotension, or conduction abnormalities.
Take diltiazem at the same time each day to maintain steady levels. If a dose causes noticeable dizziness or fatigue, timing the dose at bedtime may help—ask your clinician before changing schedules. Avoid abruptly stopping diltiazem; sudden discontinuation can precipitate rebound angina or loss of rate control. Always follow your prescriber’s instructions and the specific brand’s medication guide, because bioequivalence and release characteristics can vary among formulations (e.g., Cardizem CD, Cartia XT, Tiazac, and generics).
Because diltiazem slows AV nodal conduction and lowers blood pressure, monitoring is important. Check your heart rate and blood pressure regularly, especially during dose changes. Contact your clinician if you develop resting heart rate below your provider’s threshold (commonly under 50–55 bpm), symptomatic dizziness, near-syncope, or new/worsening shortness of breath. People with preexisting low blood pressure, bradycardia, or conduction defects need extra caution.
Diltiazem is metabolized by CYP3A4 and can interact with many drugs. Tell your healthcare professional about all prescription medications, over-the-counter products, and supplements, including statins, antiarrhythmics, beta-blockers, digoxin, antifungals, macrolide antibiotics, anticonvulsants, HIV medications, and herbal products like St. John’s wort. Avoid grapefruit and grapefruit juice, which can increase diltiazem levels and raise the risk of adverse effects.
Inform your provider if you have heart failure with reduced ejection fraction, sick sinus syndrome, second- or third-degree AV block, significant liver or kidney disease, or a history of severe dermatologic reactions. Discuss pregnancy and breastfeeding; safety data are limited, so clinicians weigh risks vs benefits and may choose alternative therapies in certain scenarios. Alcohol can amplify blood pressure–lowering and sedative effects; moderation and consistent patterns help reduce surprises in blood pressure or heart rate control.
Do not use diltiazem if you have hypersensitivity to diltiazem or any component of the formulation; severe hypotension; acute myocardial infarction with pulmonary congestion; second- or third-degree AV block or sick sinus syndrome without a functioning pacemaker; or cardiogenic shock. Non-dihydropyridine calcium channel blockers like diltiazem are generally avoided in patients with heart failure with reduced ejection fraction due to negative inotropic effects unless a specialist determines otherwise.
Use caution and specialist guidance if you have advanced liver impairment, as metabolism may be reduced and dose adjustments are often necessary. In combination with other AV nodal–blocking agents (e.g., beta-blockers, certain antiarrhythmics), diltiazem can markedly slow heart rate or precipitate AV block. Careful selection, dosing, and monitoring are required when such combinations are clinically indicated.
Common side effects include peripheral edema (swelling of ankles or feet), headache, flushing, dizziness, fatigue, and gastrointestinal symptoms such as constipation, nausea, or dyspepsia. Edema results from arteriolar dilation increasing capillary hydrostatic pressure; it is usually dose-related and not necessarily a sign of fluid overload. Lifestyle measures like leg elevation and compression stockings sometimes help, but persistent or uncomfortable swelling should be reported to your clinician.
Less common effects include bradycardia, hypotension, AV block, rash, and gingival overgrowth. Rare but serious adverse reactions can include severe hypotension, heart failure decompensation in susceptible individuals, significant conduction disturbances, hepatic enzyme elevations, or severe cutaneous reactions. Seek urgent care for chest pain that is new or worsening, fainting, severe shortness of breath, or signs of an allergic reaction (e.g., facial swelling, difficulty breathing, hives).
Constipation is a frequent complaint with diltiazem and other calcium channel blockers. Hydration, gradual dietary fiber increases, and regular activity are typical first steps. If needed, your provider may recommend stool softeners or adjust therapy. Report persistent constipation, as it can often be managed without discontinuing effective cardiovascular treatment.
Diltiazem is a substrate and moderate inhibitor of CYP3A4, so it can raise blood levels of coadministered CYP3A4 substrates and, in turn, be affected by strong inhibitors or inducers. Notable interactions include:
- Beta-blockers (e.g., metoprolol, propranolol): Additive effects on AV nodal conduction and heart rate may cause bradycardia or block. Combination can be appropriate with careful monitoring.
- Digoxin: Diltiazem can increase digoxin levels; most clinicians monitor digoxin concentration and watch for toxicity (nausea, visual disturbances, arrhythmias).
- Statins (e.g., simvastatin, lovastatin): CYP3A4 inhibition can increase statin exposure. Dose limits or alternative statins (e.g., pravastatin, rosuvastatin) are often recommended to reduce myopathy risk.
- Antiarrhythmics and other AV nodal agents (e.g., amiodarone, sotalol, clonidine): Risk of bradycardia and conduction abnormalities.
- Macrolide antibiotics, azole antifungals, some HIV protease inhibitors: CYP3A4 inhibition may elevate diltiazem levels and potentiate hypotension/bradycardia.
- Anticonvulsants and rifamycins: CYP3A4 induction can reduce diltiazem effectiveness, requiring reassessment of therapy.
Avoid grapefruit and grapefruit juice, which inhibit intestinal CYP3A4 and can increase diltiazem exposure. Discuss all new medications with your provider to maintain safe, effective rate control and blood pressure management.
If you miss a dose, take it as soon as you remember unless it is close to your next scheduled dose. If it is near the next dose, skip the missed dose and resume your regular schedule. Do not double up to make up for a missed dose, as that can cause excessive bradycardia or hypotension. For patients on multiple daily doses of immediate-release tablets, consider setting reminders or using a pill organizer to help maintain consistent dosing.
Call emergency services immediately if an overdose is suspected. Symptoms may include profound dizziness, fainting, severe hypotension, bradycardia, AV block, lethargy, confusion, or shortness of breath. If the person is conscious and able to swallow, do not induce vomiting unless directed by poison control. In the United States, you can contact Poison Help at 1-800-222-1222 for prompt guidance while waiting for emergency care. Medical management may involve cardiac monitoring, IV fluids, vasopressors, calcium, and other supportive measures under hospital supervision.
Store diltiazem at room temperature away from excessive heat, light, and moisture. Keep tablets and capsules in their original container with the lid tightly closed. Do not store in a bathroom where humidity fluctuates. Keep out of reach of children and pets. If your pharmacist dispenses a different brand or a generic with a different appearance, confirm the product and instructions before taking it. Dispose of expired or unused medication through pharmacy take-back programs or according to FDA guidance; do not flush unless specifically instructed.
Reddit discussions about diltiazem commonly revolve around real-world experiences managing atrial fibrillation rate control and high blood pressure, comparing diltiazem to beta-blockers like metoprolol. Users frequently note improved heart rate control and fewer palpitations, while some report trade-offs such as ankle swelling, constipation, or exercise intolerance due to lower heart rate. Extended-release vs immediate-release timing is a popular topic; many prefer once-daily ER dosing for steadier effects. Community members also highlight interaction cautions—especially avoiding grapefruit, spacing other medications, and double-checking combinations with digoxin or statins—and share lifestyle tips like hydration, fiber intake, and compression socks to address edema and constipation.
A recurring theme is personalization: doses that work for one person may be too sedating or insufficient for another. Several posters encourage using home blood pressure cuffs and heart rate monitors, and partnering closely with a clinician for safe titration. Others mention gradual transitions from beta-blockers to diltiazem, noticing different side-effect profiles. While Reddit can offer helpful anecdotes, users consistently remind readers to prioritize professional medical advice for dosing and drug-interaction decisions.
On WebMD’s patient review pages, many individuals report that diltiazem effectively lowers blood pressure, reduces the frequency and intensity of angina episodes, and provides reliable rate control for atrial fibrillation. Positive comments often point to improved exercise tolerance and fewer palpitations once the right extended-release dose is reached. Some reviewers mention that switching from a beta-blocker reduced fatigue or cold extremities, while others experienced the opposite and preferred their prior therapy—highlighting the individualized nature of response.
Commonly cited downsides include ankle swelling, constipation, headaches, and episodic dizziness, especially during early dose adjustments. A subset of patients note that edema was dose-related and improved after a dosage reduction or a switch to a different formulation. Reviews frequently emphasize the importance of monitoring, avoiding grapefruit, and discussing potential interactions with statins and digoxin. Overall, patient comments portray diltiazem as effective for many cardiovascular indications, with tolerability that varies by dose, formulation, and concurrent medications.
In the United States, diltiazem is a prescription-only medication. By law, a licensed healthcare professional must evaluate whether it is appropriate for you, prescribe the correct dose and formulation, and provide ongoing monitoring for safety and efficacy. Any pharmacy dispensing diltiazem must be properly licensed, and reputable online services should verify your identity, use secure systems, and comply with federal and state regulations. Be cautious of websites that offer cardiovascular medications without clinician involvement, as these may be unsafe or illegal.
Nunzia Pharmaceutical offers a legal and structured pathway to obtain diltiazem without presenting a preexisting prescription by integrating telehealth evaluation with pharmacy fulfillment. In practice, that means a U.S.-licensed clinician reviews your health history, medications, and vital parameters, and—if appropriate—issues a prescription that Nunzia’s partner pharmacy dispenses and ships to you. This approach maintains medical oversight and regulatory compliance while removing the need for an in-person visit or paper prescription. Patients benefit from convenience, transparent pricing, and access to pharmacist counseling, while still adhering to safety standards designed to protect your heart health.
Before purchasing, verify licensure, look for accreditation (such as NABP’s .pharmacy domain or other state-level validations), and ensure there is a clear process to contact both the clinician and the pharmacist. Keep all follow-up appointments, track blood pressure and heart rate at home, and report side effects promptly so your care team can adjust therapy as needed. This ensures you receive the benefits of diltiazem—lower blood pressure, fewer angina episodes, reliable rate control—under the appropriate safeguards.
Diltiazem is a calcium channel blocker that relaxes blood vessels and slows electrical conduction through the heart. By blocking L-type calcium channels, it lowers blood pressure, reduces chest pain (angina) by improving blood flow to the heart, and slows heart rate by suppressing AV nodal conduction.
It is prescribed for hypertension, chronic stable and vasospastic (Prinzmetal) angina, and rate control in certain arrhythmias such as atrial fibrillation, atrial flutter, and paroxysmal supraventricular tachycardia.
Immediate-release tablets act within about an hour and usually require dosing multiple times per day. Extended-release capsules/tablets provide steady control over 24 hours for once-daily or twice-daily dosing, improving adherence and minimizing peaks and troughs.
Take it exactly as directed, at the same time each day. Swallow extended-release forms whole—do not crush or chew. You can take it with or without food, but be consistent. If switching formulations or brands, confirm the dose and schedule with your prescriber.
Common effects include dizziness, headache, fatigue, flushing, nausea, constipation (less than with verapamil), and ankle swelling (peripheral edema). Most are mild and improve over time.
Seek help for severe dizziness or fainting, very slow heart rate, chest pain that worsens, shortness of breath, swelling that progresses rapidly, signs of heart failure (rapid weight gain, leg swelling), allergic reactions, or yellowing of the skin/eyes. Diltiazem can rarely cause AV block or worsen heart failure.
People with very low blood pressure, sick sinus syndrome or second/third-degree AV block without a pacemaker, acute myocardial infarction with pulmonary congestion, or decompensated heart failure should avoid it. Use caution with reduced ejection fraction heart failure, significant liver impairment, or in older adults who may be more sensitive to bradycardia and hypotension.
Yes. Diltiazem slows conduction through the AV node and is commonly used to control ventricular rate in atrial fibrillation and atrial flutter. It does not convert rhythm to normal sinus; it controls rate.
Diltiazem is a CYP3A4 inhibitor and is metabolized by the same pathway. It can raise levels of drugs like certain statins (simvastatin, lovastatin), cyclosporine, tacrolimus, and some benzodiazepines. Strong CYP3A4 inducers (rifampin, carbamazepine, St. John’s wort) can lower diltiazem levels. Combining with beta-blockers, digoxin, or other AV-nodal blockers increases the risk of slow heart rate or heart block. Always review all medicines and supplements with your clinician or pharmacist.
Grapefruit can increase diltiazem levels and side effects; it’s best to avoid or limit it. Alcohol may enhance blood pressure–lowering and dizziness; use cautiously and avoid driving if you feel lightheaded.
Immediate-release tablets begin working within 30–60 minutes and last about 6–8 hours. Extended-release products provide 12–24 hours of effect depending on the formulation. Intravenous diltiazem for acute rate control works within minutes.
Take it as soon as you remember unless it’s close to the next dose. Skip the missed dose if it’s almost time for the next one. Do not double up. For extended-release, try to take it at a consistent time each day.
Data in pregnancy are limited; it’s generally used only if benefits outweigh risks. Discuss alternatives if you’re planning pregnancy. Diltiazem passes into breast milk in small amounts; if used during breastfeeding, monitor the infant for unusual sleepiness, poor feeding, or slow heart rate and consult your pediatrician.
Yes. Peripheral edema (especially around the ankles) can occur and may show up as weight gain from fluid. Report new or worsening swelling to your clinician, especially if accompanied by shortness of breath.
Diltiazem is mainly metabolized by the liver. Routine liver function monitoring may be considered if you have liver disease or symptoms of liver problems. Dose adjustments are usually not needed for kidney impairment, but your prescriber will individualize care.
Do not stop abruptly without medical guidance, especially if you take it for angina or arrhythmia. Stopping suddenly may worsen chest pain or lead to rapid heart rates. Your clinician may advise a taper.
Yes, but diltiazem can reduce heart rate and blood pressure, which may change how you feel during exertion. Start gradually, monitor for dizziness or unusual fatigue, and discuss target heart rate and symptoms with your clinician.
Diltiazem can increase blood levels of simvastatin and lovastatin, raising the risk of muscle-related side effects. Dose limits apply when these are used together; alternatives like pravastatin or rosuvastatin may be preferred. Review your statin choice and dose with your prescriber.
Yes, but start low and go slow. Older adults are more prone to dizziness, slow heart rate, and drug interactions. Regular blood pressure and pulse checks are helpful.
Both are non-dihydropyridine calcium channel blockers that slow heart rate and lower blood pressure. Verapamil tends to have stronger heart rate–slowing and constipation effects; diltiazem is often better tolerated while still providing rate control and angina relief.
For uncomplicated hypertension, amlodipine (a dihydropyridine) is often preferred because it lowers blood pressure reliably with once-daily dosing and minimal effect on heart rate. Diltiazem is a good option when rate control or angina relief is also desired.
Both help angina, but they act differently. Extended-release nifedipine reduces vascular resistance without slowing heart rate, whereas diltiazem also slows AV conduction and heart rate. For patients with angina plus fast heart rates, diltiazem may be advantageous; for vasospastic angina, dihydropyridines like amlodipine or nifedipine are often first-line.
Verapamil more commonly causes constipation and can lead to greater bradycardia and AV block. Diltiazem tends to cause less constipation and may be better tolerated, though both can cause dizziness, low blood pressure, and edema.
Peripheral edema is more common with dihydropyridines like amlodipine due to arteriolar dilation without venous dilation. Diltiazem can cause edema, but typically at a lower rate. If edema occurs on amlodipine, switching to or adding a different class (e.g., ACE inhibitor) may help.
Amlodipine does not slow AV nodal conduction and is not used for rate control. Diltiazem is commonly used to control heart rate in atrial fibrillation and flutter.
Yes, clinicians sometimes combine a non-dihydropyridine (diltiazem) with a dihydropyridine (amlodipine) for additive blood pressure and antianginal effects. Close monitoring is needed for low blood pressure, edema, and heart rate.
Felodipine is a dihydropyridine that primarily dilates blood vessels and does not slow heart rate. Diltiazem lowers blood pressure and slows heart rate/AV conduction. Choice depends on whether rate control is needed and on side effect profiles.
Oral nicardipine treats hypertension; IV nicardipine is commonly used for hypertensive emergencies and neurologic indications due to potent vasodilation and titratability. Diltiazem is favored for chronic angina, hypertension with a need for rate control, and acute rate control in atrial fibrillation (IV form).
Clevidipine is an ultra–short-acting IV dihydropyridine used for rapid blood pressure control in surgical and critical care settings. Diltiazem is available orally and IV, with added effects on heart rate and AV node, making it useful for arrhythmias.
Tolerability varies. Many patients find diltiazem causes less constipation and slightly fewer conduction issues, while verapamil may be more effective for certain arrhythmias or migraine prevention. Individual response and interactions guide the choice.
Non-dihydropyridines (diltiazem, verapamil) can depress contractility and are generally avoided in HFrEF. Dihydropyridines like amlodipine are considered neutral on mortality and are preferred if a calcium channel blocker is needed.
Yes. Diltiazem and verapamil are stronger CYP3A4 inhibitors and require lower maximum doses of simvastatin or lovastatin. Amlodipine also interacts with simvastatin but allows a higher maximum dose than diltiazem or verapamil. Alternatives like pravastatin or rosuvastatin avoid this issue.
Both lower blood pressure, which reduces cardiovascular risk. Large outcome data are robust for dihydropyridines like amlodipine in hypertension. Diltiazem has strong evidence in angina and rate control; in uncomplicated hypertension, amlodipine has more outcomes data, but the best drug is the one you tolerate and take consistently.
Both are effective, but dihydropyridines such as amlodipine or nifedipine are often preferred first-line. Diltiazem is also commonly used and can be an excellent option, especially if heart rate reduction is desired.
Verapamil has more historical use and supporting evidence for cluster headaches and some migraines. Diltiazem has less evidence. Neither is first-line for migraine; discuss options with a specialist.
Yes. Amlodipine has a long half-life allowing stable once-daily dosing. Many diltiazem products are once daily, but some require twice-daily dosing depending on the formulation. Always confirm your specific product’s schedule.