Home › Medications › Diltiazem (Cardizem)
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Never give without veterinary direction

Also sold as Cardizem, Cardizem CD, Dilacor XR, Tiazac, Adizem

This drug does have veterinary uses, but the product and the amount have to be chosen by a vet who knows your dog. There is no at-home dose.

DogSafe severity score
8/10

Diltiazem is used in dogs for certain abnormal heart rhythms, always under veterinary direction. An overdose slows the heart and drops blood pressure at the same time, and the extended-release versions extend both effects for many hours.

Call a vet or poison control now. Do not wait for symptoms.

ASPCA Animal Poison Control (888) 426-4435 or Pet Poison Helpline (855) 764-7661. A consultation fee may apply.

Educational reference. Not individualized veterinary advice.(more)

See this page's cited references for supporting information and our Sources page for the reference organizations we use. Citations do not imply that those organizations reviewed or endorsed DogSafe.

Part of Heart and blood-pressure medication on our medication safety hub.

If your dog ate Diltiazem (Cardizem), call now

Do not wait for symptoms and do not wait until you have filled in the form below. Call first, then use the checklist while you are on the phone.

Exposure details to have ready

These are the questions a veterinarian or poison-control operator will ask. Fill in what you know and leave the rest blank. This tool does not estimate a dose or a risk score: medication risk depends on the exact ingredient, strength, and formulation, so the assessment has to come from the clinician on the call.

Signs so far
Before you call
  • Keep the package, blister pack, or prescription bottle. The strength and the full ingredient list are what make the advice specific.
  • Do not induce vomiting unless a veterinarian or poison-control professional tells you to. It is the wrong move for several medications and can cause harm on its own.
  • Do not give milk, food, salt, hydrogen peroxide, or any home remedy on your own.
  • Do not give a second dose of anything to make up for one you think was missed.
  • Count what is left in the packet, so the number missing can be worked out.

Your exposure summary

Read this down the phone or paste it into a message to your vet. It stays on your device; nothing here is sent to DogSafe.

Why Diltiazem (Cardizem) is dangerous

Diltiazem is a calcium-channel blocker that acts on the heart itself as well as on blood vessels, which is why it is used for rhythm control rather than simply for blood pressure. Too much slows the heart rate and lowers blood pressure together, a combination that produces weakness, collapse and, in serious cases, dangerous rhythm disturbances. Most of the products in a household are extended-release, so the effect builds over hours and a normal-seeming dog early on is not reassurance.

Part of the Amlodipine (Norvasc) guide

For related dog-safety questions and product-by-product answers, see the complete amlodipine (norvasc) guide.

Signs to watch for

Sedation, wobbliness, weakness, vomiting, slowed or labored breathing, or a heart rate that seems unusually fast or slow

Related items

Check the exact item or ingredient before assuming two similar exposures carry the same risk.

What to do next

Move the container out of reach, count what is missing, note the strength and the time, and call with the packet in front of you.

🚨Step-by-step: what to do in the first 10 minutes →
Animal poison control

A closer look at diltiazem (cardizem)

Diltiazem is a calcium-channel blocker that acts on the heart itself as well as on blood vessels, which is why it is used for rhythm control rather than simply for blood pressure. Too much slows the heart rate and lowers blood pressure together, a combination that produces weakness, collapse and, in serious cases, dangerous rhythm disturbances. Most of the products in a household are extended-release, so the effect builds over hours and a normal-seeming dog early on is not reassurance. The details below use the specific facts for this exposure, rather than treating it like every other medication question.

1. Start with the exact exposure

For a closely related comparison, read Amlodipine (Norvasc). There is no at-home dose for this drug, including where a vet has prescribed it before. The right amount depends on your dog's weight, the exact product, and what else your dog takes, and it has to be set by a vet who knows the case.

2. Use the facts to decide whether to monitor or call

Another helpful reference is Metoprolol (Lopressor). Prevent any further access and call for advice. Do not give a dose of your own, and do not induce vomiting unless a veterinary professional directs you to. Call for any exposure that was not the dose your vet set, for a chewed container, or for sedation, weakness, unsteadiness, vomiting, or changes in breathing or heart rate.

3. If the details are uncertain

Follow the first 10 minutes guide. Move the container out of reach, count what is missing, note the strength and the time, and call with the packet in front of you.

FAQ

How much Diltiazem (Cardizem) is dangerous?

There is no at-home dose for this drug, including where a vet has prescribed it before. The right amount depends on your dog's weight, the exact product, and what else your dog takes, and it has to be set by a vet who knows the case.

Can I treat this at home?

Prevent any further access and call for advice. Do not give a dose of your own, and do not induce vomiting unless a veterinary professional directs you to.

When should I call the vet?

Call for any exposure that was not the dose your vet set, for a chewed container, or for sedation, weakness, unsteadiness, vomiting, or changes in breathing or heart rate.

SourcesUpdated August 10, 2026
  • Merck Veterinary Manual — poisonings from human prescription drugs (cardiovascular agents)
  • ASPCA Animal Poison Control Center — human medications
  • Pet Poison Helpline — top 10 human medications poisonous to pets
Read DogSafe's sources and review policy →
Compiled from veterinary poison-control and medical reference sources, including the ASPCA Animal Poison Control Center, the Pet Poison Helpline, and the Merck Veterinary Manual. This is general educational information, not a diagnosis or a substitute for examination by your veterinarian. DogSafe's severity ratings are general editorial hazard ratings, not a calculation of your dog's exposure. They cannot establish that an amount is safe. In an emergency, call ASPCA Animal Poison Control at 888-426-4435 or the Pet Poison Helpline at 855-764-7661.