Diltiazem

This product page describes diltiazem, a prescription calcium channel blocker used in cardiovascular care. It is commonly prescribed for conditions such as high blood pressure, chest pain (angina), and certain fast heart rhythms. The sections below summarize forms, dosing patterns, safety considerations, and practical handling for people using a prescription referral service, including those paying cash without insurance.

What diltiazem Is and How It Works

This medicine is in the calcium channel blocker class. It affects how calcium enters heart and blood vessel cells, which can relax blood vessels and reduce the heart’s workload. Some formulations also slow conduction through the AV node (the heart’s electrical “gatekeeper”), which can help control ventricular rate in certain supraventricular arrhythmias. Ships from Canada to US for cross-border access through licensed dispensing partners.

Different formulations are designed for different release patterns. Immediate-release products act over a shorter period, while extended-release versions spread the dose over the day. That release design matters for how often it is taken and whether the tablet or capsule can be altered.

Prescription details may be confirmed with the prescriber when required.

For related options in this therapeutic area, browse the Cardiovascular Medicines list.

Who It’s For

Prescribers may use this therapy to manage hypertension, to prevent or reduce angina symptoms, or to help control rate in certain supraventricular tachycardias. The specific indication depends on the formulation and the clinical goal. For condition-focused browsing, see hubs such as Managing Hypertension, Angina Overview, Atrial Fibrillation, and Supraventricular Tachycardia.

This medicine is not appropriate for everyone. Contraindications and higher-risk situations can include certain conduction disorders (for example, some types of heart block), very low blood pressure, cardiogenic shock, or allergy to ingredients. Extra caution is often needed in people with heart failure, significant liver or kidney impairment, or a history of slow heart rate. Pregnancy and breastfeeding considerations vary; the prescriber should weigh risks and benefits and review alternatives when needed.

Dosage and Usage

Directions depend on the exact formulation (immediate-release versus extended-release) and the reason it was prescribed. Some products are taken multiple times per day, while others are designed for once-daily dosing. Labels such as ER, XR, or CD usually indicate an extended-release design. Food instructions can vary by product, so the pharmacy label and the official monograph should be followed.

With diltiazem, extended-release tablets or capsules should generally be swallowed whole unless the specific product information says otherwise. Crushing, chewing, or splitting can change how the drug is released and may raise the risk of side effects. Missed-dose instructions also depend on the product; many labels advise taking it when remembered unless it is close to the next scheduled dose.

Quick tip: Compare the container label (ER/XR/CD) to the prescriber’s directions before each refill.

For general cardiovascular medication context, the guides Atenolol And Hypertension Guide and Acebutolol Uses And Dosage can help explain common monitoring terms.

Strengths and Forms

Formulations may be labeled as diltiazem hydrochloride (also written as HCl) and are available in immediate-release tablets and extended-release capsules or tablets. Availability varies by pharmacy and market, and the same milligram strength can behave differently depending on whether it is immediate-release or extended-release.

Common presentations include short-acting tablets (often used in divided daily doses) and once-daily or twice-daily extended-release products. Brand families that may be encountered include Cardizem and Cartia XT; some people will also see different “release” abbreviations such as XR or CD. Any substitution between release types should be directed by the prescriber because dose timing and equivalence are product-specific.

For additional heart-health resources, browse Cardiovascular Articles.

Storage and Travel Basics

Store at room temperature in a dry place, away from heat and moisture. Keep the medication in the original container with the label intact, and close it tightly after each use. Avoid storing bottles in bathrooms or near kitchen sinks where humidity is frequent. Do not use tablets or capsules past the expiry date printed by the dispensing pharmacy.

For travel, pack the medicine in carry-on luggage to reduce exposure to temperature extremes. Keep a copy of the prescription or a photo of the pharmacy label for identification. If a dosing schedule crosses time zones, the prescriber or pharmacist can clarify how to keep spacing consistent without changing the total daily amount.

Side Effects and Safety

Common side effects can include headache, dizziness, flushing, constipation, nausea, and swelling of the ankles or feet (peripheral edema). Some people notice fatigue or lightheadedness, especially when starting therapy or after a dose increase. These effects may be more pronounced when standing quickly or when combined with other blood-pressure-lowering medications.

More serious reactions can involve very slow heart rate, fainting, worsening shortness of breath, signs of low blood pressure, severe skin reactions, or symptoms that could suggest liver problems (such as dark urine or yellowing of the skin). Because diltiazem can affect heart rate and conduction, clinicians may recommend monitoring blood pressure and pulse at home and periodic ECGs in selected patients.

A licensed Canadian pharmacy dispenses medication after prescription review.

Why it matters: A low pulse plus dizziness can signal excessive rate slowing.

For medication-safety frameworks used in clinical settings, see Apixaban Nursing Considerations.

Drug Interactions and Cautions

diltiazem can interact with many commonly used therapies because it affects heart conduction and is processed through CYP pathways in the liver. Combining it with other agents that slow heart rate (such as beta blockers or certain antiarrhythmics) may increase the risk of bradycardia or heart block. It may also raise levels of some drugs by inhibiting metabolism, which is especially relevant for selected statins and other narrow-therapeutic-index medications.

Other important cautions include grapefruit products (which can change drug levels for some people), alcohol (which may worsen dizziness), and over-the-counter products that affect blood pressure. A complete and current medication list should include prescriptions, supplements, and “as needed” items. Before planned procedures, anesthesia teams should be told about all cardiovascular medicines because perioperative blood pressure and rhythm management may be adjusted.

• Rate-slowing combinations: may compound effects
• CYP interactions: may alter drug levels
• Grapefruit products: may increase exposure
• OTC decongestants: may raise blood pressure

Compare With Alternatives

Several other drug classes may be used depending on the condition being treated. Another non-dihydropyridine calcium channel blocker, verapamil, can have similar rate-slowing effects but differs in tolerability and interaction profile; see the Verapamil Product Page for its formulation overview. For blood pressure and angina control, dihydropyridine calcium channel blockers emphasize vessel relaxation more than rate control; an example is Nifedipine XR.

Outside calcium channel blockers, prescribers may consider beta blockers, ACE inhibitors, ARBs, thiazide-type diuretics, or combination products depending on blood pressure goals and comorbidities. For rhythm management, the choice may be influenced by underlying heart function, conduction findings, and concurrent anticoagulation plans. Comparisons should be made using the official product monographs and the prescriber’s goals for therapy.

Pricing and Access

For people comparing cash-pay options, diltiazem cost can vary by formulation, release type, and strength, even when the active ingredient is the same. Generic versions are common, but the specific manufacturer and release design can still affect how the medication should be taken. If assistance programs are relevant, see Current Promotions for site-listed updates (availability and eligibility may change).

This prescription referral service can support cash-pay access for some people without insurance.

To request dispensing through participating pharmacies, a valid prescription is required. In many cases, the prescription can be uploaded or sent by the prescriber, and the pharmacy label will reflect the exact formulation provided. If the prescriber changes therapy from immediate-release to extended-release (or vice versa), confirm that the new directions and the container label match before starting the new supply.

Authoritative Sources

For the most reliable details on indications, contraindications, and formulation-specific directions, consult official references and the product monograph provided with the dispensed medication. These sources are also helpful for verifying whether a specific ER/XR/CD product can be opened, split, or taken with food, since those instructions differ by manufacturer.

• MedlinePlus Medicine Information — consumer-friendly summary of uses, precautions, and side effects
• NHS Medicines Guidance — practical administration and safety notes

To proceed on the site, submit the prescription documentation and select prompt, express, cold-chain shipping at checkout.

This content is for informational purposes only and is not a substitute for professional medical advice.