Diltiazem is a nondihydropyridine calcium channel blocker that relaxes the smooth muscle in arterial walls and slows electrical conduction through the atrioventricular (AV) node. By decreasing vascular resistance, it lowers blood pressure and reduces the heart’s oxygen demand. By slowing AV nodal conduction, it helps control heart rate in certain supraventricular arrhythmias. These combined effects make it versatile in cardiovascular care.
Clinically, diltiazem is used to treat hypertension (high blood pressure), chronic stable angina, and vasospastic (Prinzmetal) angina. It is also used for rate control in atrial fibrillation and atrial flutter, and for paroxysmal supraventricular tachycardia. In angina, diltiazem improves exercise tolerance and reduces frequency of chest pain by improving coronary blood flow and decreasing myocardial oxygen demand.
Off-label, clinicians sometimes use diltiazem for conditions such as esophageal spasm or certain migraine patterns, though evidence varies and specialist guidance is recommended. As with any prescription therapy, decisions are individualized: comorbid conditions, other medications, heart rate and rhythm, and treatment goals influence whether diltiazem is appropriate.
Because cardiovascular risk reduction is multifactorial, diltiazem is most effective when paired with lifestyle measures—sodium reduction, weight management, regular activity as approved by a clinician, moderation of alcohol, and smoking cessation—to lower the risk of heart attack, stroke, and hospitalization.
Diltiazem is available in immediate-release (IR) tablets typically taken three to four times daily, and extended-release (ER) capsules or tablets designed for once-daily or twice-daily dosing. ER formulations should be swallowed whole; do not crush or chew. Not all ER products are interchangeable, so follow the exact brand and dosing schedule prescribed by your clinician and pharmacy.
For hypertension, clinicians commonly start an ER formulation, often 120–180 mg once daily, then titrate based on blood pressure response and tolerability. Usual maintenance doses range from 180–360 mg daily; some patients may require higher doses depending on the specific product, with maximum doses set by the manufacturer’s labeling. Dose adjustments typically occur at 1- to 2-week intervals.
For chronic stable or vasospastic angina, IR diltiazem might begin at 30 mg four times daily with gradual increases, or an ER product may be used at 120–240 mg once daily, titrated to symptom control. For arrhythmia rate control, dosing is individualized; hospital-based initiation or close outpatient monitoring is often recommended, especially if combined with other rate-controlling drugs.
Food can affect absorption of some ER formulations; check your product’s instructions. In general, take diltiazem consistently at the same time every day, with or without food if labeling allows. Avoid grapefruit and grapefruit juice, which can increase diltiazem levels and the risk of side effects by inhibiting CYP3A4 metabolism.
Never change your dose or discontinue abruptly without medical advice. If blood pressure readings drop too low (e.g., dizziness, lightheadedness, fainting) or your heart rate is unusually slow, contact your clinician. Home blood pressure monitoring and periodic heart rate checks help guide safe titration and long-term control.
Tell your clinician about all medical conditions before starting diltiazem, especially any history of heart block, sick sinus syndrome, heart failure, low blood pressure, liver or kidney disease, and rhythm disorders. Diltiazem can slow heart conduction and may not be appropriate if you have conduction system disease without a pacemaker.
Older adults and those with hepatic impairment may require lower starting doses and slower titration. Liver enzymes may occasionally increase with therapy; clinicians may monitor periodically in patients with underlying disease or if symptoms suggest hepatic dysfunction (fatigue, dark urine, jaundice, abdominal pain).
During pregnancy and breastfeeding, the risk-benefit balance should be carefully considered. Data are limited; if diltiazem is needed, use the lowest effective dose and monitor closely. Discuss family planning and lactation considerations with your healthcare provider to ensure the safest approach.
If you are scheduled for surgery or dental procedures, inform your surgical team that you take diltiazem. Alcohol may amplify blood pressure–lowering effects and dizziness; moderation and consistency are advisable. As with any antihypertensive, rise slowly from seated or lying positions to reduce the risk of falls.
Diltiazem is contraindicated in patients with hypersensitivity to diltiazem or any component of the formulation; in sick sinus syndrome or second- or third-degree AV block except in the presence of a functioning pacemaker; in severe hypotension; and in acute myocardial infarction with pulmonary congestion. These conditions heighten the risk of significant bradycardia, conduction block, or hemodynamic compromise.
Use caution in heart failure with reduced ejection fraction. Although diltiazem may be used in select patients under specialist guidance, nondihydropyridine calcium channel blockers can depress myocardial contractility and worsen decompensated heart failure. In such cases, alternative therapies are often preferred.
Common side effects include peripheral edema (ankle or foot swelling), headache, flushing, dizziness, fatigue, and gastrointestinal symptoms such as constipation, nausea, or dyspepsia. Many of these are dose-related and may improve as your body adapts or with dose adjustment under medical supervision.
Cardiovascular effects can include bradycardia, orthostatic hypotension, and in susceptible patients, conduction disturbances. If you experience fainting, a very slow pulse, or new/worsening chest pain, seek medical attention promptly. Rarely, diltiazem may precipitate or worsen heart failure symptoms (shortness of breath, rapid weight gain, swelling).
Less common effects include rash, pruritus, photosensitivity, and gingival hyperplasia (gum overgrowth) with long-term use. Report unusual bleeding of the gums or oral changes to your clinician and maintain good dental hygiene with regular professional cleanings.
Serious but uncommon adverse reactions include significant liver injury (elevated enzymes, jaundice), severe skin reactions, and marked AV block. Seek urgent care if you notice yellowing of the skin or eyes, severe abdominal pain, widespread rash, or signs of severe allergic reaction such as swelling of the face or throat or difficulty breathing.
Diltiazem is metabolized by CYP3A4 and is also a moderate inhibitor of CYP3A4 and P-glycoprotein. This means other drugs can raise or lower diltiazem levels, and diltiazem can increase levels of other medications. Always provide a complete medication list, including over-the-counter products and supplements, to your clinician and pharmacist.
Avoid grapefruit and grapefruit juice, which inhibit CYP3A4 in the gut, potentially increasing diltiazem concentration and the risk of side effects like hypotension or bradycardia. Consistent dietary habits help maintain stable drug levels and predictable blood pressure control.
Additive cardiovascular effects can occur with beta blockers (e.g., metoprolol, atenolol), amiodarone, or other agents that slow heart rate or AV conduction, increasing the risk of bradycardia or heart block. If combination therapy is indicated, careful dosing and monitoring are essential.
Diltiazem may increase exposure to statins metabolized by CYP3A4, particularly simvastatin and lovastatin. To reduce the risk of myopathy, clinicians often limit the simvastatin dose (e.g., to 10 mg daily) or switch to alternatives less affected by CYP3A4 inhibition (pravastatin or rosuvastatin). Report muscle pain, weakness, or dark urine promptly.
Other clinically important interactions include increased levels of digoxin, cyclosporine, tacrolimus, buspirone, some benzodiazepines (e.g., midazolam, triazolam), and certain direct oral anticoagulants (e.g., apixaban) due to combined CYP3A4/P-gp effects. Inducers such as rifampin, carbamazepine, phenytoin, and St. John’s wort can reduce diltiazem levels and blunt its efficacy. Dose adjustments or alternative therapies may be necessary.
If you miss a dose of diltiazem, take it as soon as you remember unless it is close to the time of your next scheduled dose. If it is almost time for the next dose, skip the missed dose and resume your regular schedule. Do not double up or take extra doses to make up for a missed one.
For once-daily ER products, a practical approach is to take the missed dose within several hours of your usual time; after that, skip and take the next dose at your regular time. If you miss doses frequently, set reminders and discuss strategies with your clinician to support adherence.
A diltiazem overdose can cause dangerous bradycardia, low blood pressure, dizziness, fainting, shortness of breath, confusion, and, in severe cases, cardiogenic shock. If an overdose is suspected, call emergency services immediately. Do not attempt to self-treat or induce vomiting unless instructed by medical professionals.
In the emergency department, clinicians may provide advanced supportive care, including intravenous fluids, calcium, vasopressors, insulin-based therapies, or temporary pacing as appropriate. Early medical evaluation improves outcomes; bring the medication bottle to inform the care team of the exact product and strength.
Store diltiazem at room temperature, generally 68°F to 77°F (20°C to 25°C), away from excessive moisture, heat, and direct light. Keep in the original, tightly closed container with the label intact so instructions and expiration dates remain visible.
Keep all medications out of reach of children and pets. Do not use diltiazem past the expiration date, and dispose of unused or expired tablets and capsules through medicine take-back programs or according to pharmacist guidance—avoid flushing unless specifically instructed.
In the United States, diltiazem is a prescription-only medication. By law, legitimate pharmacies dispense it only after a licensed clinician has assessed the patient and issued a prescription. Any website offering diltiazem with “no prescription” and no medical evaluation is not operating within U.S. standards and may put you at risk of counterfeit or unsafe products.
Many consumers encounter the phrase “buy diltiazem without prescription” online. In a compliant model, this phrase typically refers to streamlined access where no prior prescription is required because a licensed clinician provides an evaluation (often via telehealth) and, if appropriate, issues a valid prescription that is then filled by a licensed pharmacy. This preserves safety and legality while making access more convenient.
HealthSouth MountainView offers exactly this kind of legal and structured solution. Patients complete a secure intake and, when indicated, a telehealth evaluation with a U.S.-licensed clinician. If diltiazem is appropriate, the clinician issues a prescription, the pharmacy dispenses FDA-approved product, and medications are shipped discreetly with support for refills and ongoing monitoring. Transparent pricing, clear eligibility criteria, and pharmacist counseling help ensure a safe experience.
Before purchasing, verify that: the service uses U.S.-licensed prescribers and pharmacies, requires a clinical evaluation, supplies FDA-approved diltiazem, protects your data, and provides access to follow-up care. Avoid sources that ship internationally without U.S. oversight, advertise impossibly low prices, or do not require any health information. Your heart health deserves a legitimate, medically supervised process from start to finish.
This article is for general education and is not a substitute for individualized medical advice. Always consult a healthcare professional about diagnosis, treatment options, and the safest path to obtain and use diltiazem for your specific needs.
Diltiazem is a non-dihydropyridine calcium channel blocker that relaxes blood vessels and slows electrical conduction through the AV node. This lowers blood pressure, eases angina by reducing oxygen demand, and helps control heart rate in certain arrhythmias.
It is used for high blood pressure, chronic stable angina, vasospastic (Prinzmetal’s) angina, and rate control in atrial fibrillation or atrial flutter. It can also treat certain supraventricular tachycardias and is sometimes compounded as a topical ointment for chronic anal fissures.
It is available as immediate-release tablets (multiple daily doses), extended-release capsules/tablets (once daily for most products), intravenous formulations used in hospital settings, and compounded topical ointments for specific conditions.
Take it exactly as prescribed at the same time each day. Swallow extended-release capsules/tablets whole; do not crush or chew. Some brands should be taken consistently with or without food—follow your product’s instructions. Do not stop suddenly unless your clinician tells you to.
Common effects include dizziness, headache, fatigue, flushing, nausea, constipation, and ankle swelling (edema). It can also slow the heart rate and occasionally cause gingival (gum) overgrowth.
Seek care for fainting, very slow heartbeat, severe dizziness, chest pain that worsens, shortness of breath, signs of heart failure (rapid weight gain, leg swelling), yellowing of the skin/eyes, or a widespread rash. Rarely, it can cause heart block or worsen heart failure with reduced ejection fraction.
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 atrial fibrillation with an accessory pathway (e.g., WPW) should avoid it. Use caution in liver disease and in heart failure with reduced ejection fraction.
Diltiazem affects and is affected by CYP3A4. It can raise levels of certain statins (especially simvastatin), cyclosporine, tacrolimus, some benzodiazepines, and others; your clinician may adjust doses. It can increase digoxin levels and add to heart-rate slowing with beta-blockers or amiodarone. Avoid grapefruit/grapefruit juice; St. John’s wort can reduce diltiazem levels.
Moderate alcohol can enhance dizziness and low blood pressure. High alcohol intake may alter release from some extended-release products. If you drink, do so cautiously and avoid driving or risky activities until you know your response.
Take it when you remember unless it is close to the time for your next dose. Skip the missed dose if needed and resume your regular schedule. Do not double up.
Immediate-release starts working within about 30–60 minutes, with peak effect in 2–3 hours. Most extended-release products provide steady control over 24 hours. IV diltiazem works within minutes in monitored settings.
Data in pregnancy are limited; other options are often preferred unless benefits outweigh risks. Small amounts enter breast milk; infants should be observed for feeding issues or unusual sleepiness. Discuss risks and alternatives with your clinician.
It does not typically cause fat gain, but ankle or leg swelling from vasodilation can show up as increased weight. Report sudden weight gain or swelling, as these may also signal fluid retention or heart issues.
Stopping abruptly can trigger rebound angina or blood pressure spikes. If discontinuation is needed, your clinician may taper the dose.
Your care team will monitor blood pressure, heart rate, and sometimes an ECG (PR interval) after dose changes. They may check liver enzymes and drug levels or doses of interacting medications when appropriate.
Both are non-dihydropyridine calcium channel blockers that slow heart rate and lower blood pressure. Verapamil tends to cause more constipation and has stronger negative inotropic effects, while diltiazem is often a bit easier to tolerate and slightly less constipating.
Both are effective; choice depends on patient factors and clinician preference. Diltiazem is commonly used first in the emergency setting due to good rate control and tolerability, while verapamil is an alternative, especially when migraine or cluster headache prophylaxis is also a goal.
Amlodipine (a dihydropyridine) is a potent vasodilator and a first-line option for hypertension; it does not slow heart rate. Diltiazem lowers blood pressure and also slows heart rate, making it useful when arrhythmia or angina coexists. Amlodipine may cause more ankle swelling; diltiazem may cause bradycardia.
Both relieve angina, but in different ways. Diltiazem reduces heart rate and contractility (lowering oxygen demand) and also dilates coronary arteries; amlodipine primarily dilates arteries and helps prevent vasospasm. Diltiazem is helpful when rate control is desired; amlodipine is preferred in variant (Prinzmetal’s) angina and in patients with reduced ejection fraction.
Nifedipine is a dihydropyridine with strong vasodilation and no rate-slowing; extended-release nifedipine treats hypertension and angina, while immediate-release is generally avoided for blood pressure spikes. Diltiazem adds AV nodal slowing for arrhythmias and may cause less reflex tachycardia.
Nicardipine is commonly used IV for rapid blood pressure control in the ICU and after strokes or surgery. Diltiazem is preferred when heart-rate control is also needed (e.g., atrial fibrillation), with oral forms for chronic therapy and IV for acute rate control.
Felodipine, like other dihydropyridines, more commonly causes peripheral edema. Diltiazem can cause edema too, but bradycardia and conduction slowing are more prominent concerns.
Isradipine is a dihydropyridine, so headaches, flushing, and edema are more typical; it does not slow heart rate. Diltiazem may cause constipation, bradycardia, and AV block, with a lower rate of edema compared with many dihydropyridines.
Clevidipine is an ultra–short-acting IV dihydropyridine used in critical care for tight, minute-to-minute blood pressure control; it is lipid-based and contraindicated in egg/soy allergies and certain lipid disorders. Diltiazem IV is used when both blood pressure and heart rate control (especially AF with RVR) are needed.
Yes, combining a non-dihydropyridine (diltiazem) with a dihydropyridine (e.g., amlodipine) is sometimes used for difficult angina or hypertension. Avoid combining diltiazem with verapamil due to additive heart-rate and conduction slowing unless under specialist supervision.
There is no direct dose equivalence; clinicians switch based on goals (e.g., add rate control) and patient response. Blood pressure and heart rate should be monitored closely during the transition, and extended-release products should not be crushed.
Both calcium channel blocker ointments improve fissure healing by relaxing the internal anal sphincter. Studies suggest similar effectiveness, with fewer headaches than nitroglycerin; choice often depends on availability and tolerance.
