Heart & blood pressure Dogs & Cats

Diltiazem for dogs and cats

Treats some fast heart rhythms (like atrial fibrillation), high blood pressure and heart muscle disease in cats. [1]

Last reviewed: October 2026 · 2 sources · see sources

Quick answerDiltiazem is a prescription medicine for dogs and cats. A calcium-channel blocker that slows the heart rate and relaxes vessels. The most common side effects: dogs: slow heart rate.

Key facts

Generic nameDiltiazem
Common brand namesCardizem
Used inDogs & Cats
TypeHeart & blood pressure
Prescription?Prescription
Typical US priceNot listed (no reliable public source)

What it's used for

Treats some fast heart rhythms (like atrial fibrillation), high blood pressure and heart muscle disease in cats. [1]

How it works

A calcium-channel blocker that slows the heart rate and relaxes vessels. [1]

Side effects and cautions

Common side effects: Dogs: slow heart rate. Cats: vomiting. Tiredness and low appetite. [1]

Use with care: Not for pets with very low blood pressure or certain heart blocks. [1]

Call your vet right away if your pet has trouble breathing, facial swelling, hives, collapse, or any side effect that is severe or getting worse.

About dosingDosing is your vet's call. We don't list doses because the right amount depends on your pet's weight, age, health and other medicines. Don't change a dose or stop a medicine without asking your vet, and never give a pet medicine meant for people unless your vet tells you to [2].

What it costs

We don't list a price for this one because we couldn't find a reliable public source. Ask your vet or pharmacy for a quote; prices depend on your pet's size, the dose and where you fill it.

Diltiazem FAQ

What is Diltiazem used for in dogs and cats?

Treats some fast heart rhythms (like atrial fibrillation), high blood pressure and heart muscle disease in cats.

What are the side effects of Diltiazem?

Dogs: slow heart rate. Cats: vomiting. Tiredness and low appetite.

Does Diltiazem need a prescription?

Yes. It needs a prescription from a veterinarian.

How much Diltiazem should I give my pet?

Only your veterinarian can tell you. The right dose depends on your pet's weight, health and other medicines, so we don't list doses. Never give a pet a medicine prescribed for a person or another animal without asking your vet.

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This page is general information for pet owners, not veterinary advice. Talk to your vet about your own pet.

Sources (2) — tap to show
  1. VCA Animal Hospitals – Diltiazem (veterinary drug handout)
  2. FDA – Frequently asked questions about animal drugs