How much is Zyrtec for dogs?

Zyrtec is a medicine that people use for allergies. Sometimes, vets suggest it for dogs with skin issues like itching or allergies to things around them. If a dog scratches a lot, is sensitive to bug bites, or has skin problems, the vet might recommend Zyrtec.

It’s a good idea to consider giving your dog Zyrtec for various reasons. But before you do, it’s important to know the right amount and be aware of common side effects. Always consult your vet before treating any unknown issues in your dog. A vet’s opinion ensures that you’re addressing the actual problem, preventing the risk of treating something that might seem small but could be more serious. This guide will help you figure out the correct Zyrtec dosage for your dog and how to do it safely.

What is Zyrtec?

What is Zyrtec?

Zyrtec is a medicine that helps with skin and allergy issues caused by different things. The generic version is called cetirizine. Both types of medicine work by stopping the effects of histamine in the body. Histamine is a chemical the body releases in response to things like dust, food, or chemicals. It causes allergy symptoms in the eyes, nose, throat, lungs, skin, or stomach. People have studied histamine and its role in allergies for a long time.

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Zyrtec for dogs comes in 5mg and 10mg tablets. If your dog has atopic dermatitis, you can give it every 24 hours. For allergy symptoms, it can be given every 12 hours.

Here’s how much Zyrtec to give based on your dog’s weight:

  1. Less than 10 pounds: 2.5mg (half of a 5mg tablet or a quarter of a 10mg tablet)
  2. 10–50 pounds: One 10mg tablet
  3. 50+ pounds: Up to two 10mg tablets

There’s also a liquid form that you can use with a syringe or dropper. You can put it on your dog’s food or squirt it into their mouth. Liquid Zyrtec might be easier for smaller dogs because cutting the tablets can be tricky.


Zyrtec has cetirizine as its active ingredient, which is closely related to hydroxyzine, a strong antihistamine used before surgeries. Unlike first-generation antihistamines, Zyrtec, a second-generation option, doesn’t make you feel sleepy.

In a study with dogs having itchy skin, Zyrtec reduced itching in 18% of them, with only two dogs experiencing vomiting as a side effect.

Another study showed that dogs given Zyrtec before getting histamine injections had less swelling at the injection site compared to those without Zyrtec. This study had a 100% success rate in a small group of 8 dogs.

In a different study with 12 dogs receiving histamine injections, Zyrtec’s active ingredient worked better than Benadryl in reducing the body’s immune response.

Zyrtec for dogs’ side effects

How long do Zyrtec side effects last?

Zyrtec is generally safe for dogs and doesn’t usually make them sleepy. It doesn’t affect their brain much. If you want to be extra careful, avoid giving other medicines that can make your dog more sleepy. If you’re not sure about any medicines your dog is taking, you can ask your vet if they might make your dog’s nervous system slow down. Some other side effects include:

  • Drowsiness
  • Drooling
  • Vomiting
  • Hyperactivity
  • Constipation
  • Difficulty urinating
  • Impulsiveness

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It’s not a good idea to use Zyrtec for pregnant or breastfeeding dogs because there’s not much research on its safety in these situations. Some vets might still prescribe it for these dogs if the benefits are more than the risks.

Don’t give Zyrtec to dogs allergic to antihistamines, especially ones with cetirizine or hydroxyzine, as it could cause a serious reaction called anaphylactic shock.

Be careful using this medicine in dogs with kidney or liver issues because it can stay in their system longer. Stop giving it if your dog has trouble peeing or shows other severe side effects.

Using antihistamines in the wrong way might hide signs of other illnesses, so it’s best to check with your vet to see if it’s right for your dog.

Drug Interactions

  1. Painkillers like codeine, hydrocodone, or morphine
  2. Medicines for anxiety or sleep like alprazolam, lorazepam, zolpidem, diazepam, and clonazepam
  3. Drugs that help relax muscles such as carisoprodol and cyclobenzaprine
  4. Medications for allergies taken by mouth or applied on the skin like chlorpheniramine and diphenhydramine
  5. Pseudoephedrine is found in nasal decongestants.

Allergic reactions and sensitivity

It might sound odd, but some pets can have allergies to allergy medications like Zyrtec. If your pet’s allergy symptoms get worse or if they have trouble breathing or swelling of the face, let your vet know.

Symptoms of a severe drug reaction include:

  • Hives
  • Swelling of the face, muzzle, tongue, or paws
  • Uncontrollable itching
  • Difficulty breathing
  • Confusion
  • Racing heartbeat
  • Abrupt loss of bladder or bowel control
  • Cold gums and mouth
  • Shock
  • Involuntary muscle twitching

In short, Zyrtec can be a valuable ally in managing your dog’s allergies when used responsibly and under veterinary guidance. Understanding the appropriate dosage, and potential side effects, and considering alternative options ensure the well-being of your furry companion.

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FAQs: How much is Zyrtec for dogs?

How much Zyrtec can a dog take?

Still not satisfied? Here are some frequently asked questions:

How much human Zyrtec can I give my dog?

Give your dog 0.5mg for every pound it weighs. You can safely give your dog up to 20mg of Zyrtec each day. Just give it to them by mouth.

Which is better for dogs Benadryl or Zyrtec?

Dogs may feel sleepy or tired when taking antihistamines, especially with older ones like Benadryl. However, newer ones like Zyrtec or Reactine are less likely to make them feel so tired.

Can too much Zyrtec hurt a dog?

You’ll usually give the tablets to your pet by mouth. If you give the right amount, the medicine shouldn’t cause many problems. But if you give your dog too much, it can make things worse and cause harmful effects.

Does Zyrtec make dogs sleepy?

Drowsiness is a potential side effect of Zyrtec in dogs, although it is not as common as in humans.

Is too much Zyrtec bad for dogs?

If dogs or cats accidentally eat antihistamines, it can make them very restless, tired, aggressive, or sedated. They might also have problems with their heart rate, and blood pressure, and experience vomiting, diarrhea, loss of appetite, seizures, difficulty breathing, and in extreme cases, it could lead to death.

Can my dog take Zyrtec every day?

It’s usually safe for dogs to take one tablet per day, but the right amount depends on your dog’s size and symptoms.

By Syed Habib Ahmed

Syed Habib Ahmed is a pet lover and writer having experience with all kinds of animals. Over the years he has cared dogs, cats, horses and other pets. Before writing became his full-time career, he has worked with different vets and organization who rescue animals.

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