Can You Give Your Dog Zyrtec? What to Know About Safety and Use

Itchy skin from various causes plagues many dogs, and, of course, we want to find a way to help them feel better quickly. Many of us assume the fastest way is to grab something from our medicine cabinet, and the allergy medicine Zyrtec is often present there. However, you need to know if Zyrtec will help your itchy dog and, more importantly, whether it’s safe and if there are any precautions to be aware of. Read on and find out. 

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What is Zyrtec?

Zyrtec is an antihistamine. The brand name is cetirizine. People use it to treat their allergy symptoms, which often include sneezing, runny noses, itchy eyes, and skin rashes. Zyrtec is an improvement over older antihistamines such as Benadryl because it doesn’t cause drowsiness and is long-lasting, sometimes still active for up to 24 hours. 

Can dogs take Zyrtec?

Many dogs can take Zyrtec, but only under a vet’s guidance. It is considered safe for dogs, but not every dog can take it. A vet needs to calculate the dosage, which must be very precise and based on weight and general health. Zyrtec can benefit some dogs suffering from allergies, but giving it the wrong way or without talking to your veterinarian can cause problems.

Important: Never give Zyrtec-D to your dog. Zyrtec-D contains pseudoephedrine, a decongestant that is highly toxic to dogs and can cause severe, life-threatening reactions.

Uses and benefits of Zyrtec for dogs

Zyrtec can help dogs suffering from all types of allergies, including atopic, food, and contact allergies. 

Allergies

Symptoms of allergies in dogs often include:

• Itchy skin

• Red or inflamed skin

• Chronic ear infections

• Sneezing or coughing

• Excessive licking or chewing of paws

Unlike people, dogs most often show their allergies in their skin, not by sneezing and other upper respiratory symptoms. Histamine is a chemical involved in allergies, and Zyrtec blocks the action of histamine, which can give almost immediate relief. 

Skin irritations

Zyrtec can help dogs with chronic skin irritation, often called atopic dermatitis, and hot spots. Although it may not alleviate all symptoms by itself, it can be a powerful part of a larger plan.

How to know if Zyrtec is ok for your dog to take

You need your vet’s input to determine whether your dog can take Zyrtec. Here are some considerations that help your veterinarian decide if it’s safe. 

• Your dog’s age

• Your dog’s breed and size

• Current medications

• Any pre-existing health conditions (especially kidney or liver disease)

• The type and severity of the allergy or skin issue

Pregnant dogs, nursing dogs, elderly dogs, and dogs with certain medical conditions may not be able to take Zyrtec. 

Common Zyrtec dosages for dogs

Your vet must recommend the proper dosage for Zyrtec based on your dog's weight and the condition being treated. The typical dosage of Zyrtec for dogs is about 0.5 mg per pound of body weight, given once daily. For example:

• A 10-pound dog may be given about five mg once a day.

• A 50-pound dog may be given around 25 mg once a day.

Zyrtec is available in five mg and 10 mg tablets, making it relatively easy to adjust the dose. As mentioned, always use plain Zyrtec (cetirizine) tablets or liquid, never Zyrtec-D, and avoid any formulations with added decongestants or flavorings that could harm pets. Decongestants and artificial flavoring can be dangerous. 

Important: Never attempt to calculate or adjust your dog’s Zyrtec dose without professional guidance.

Potential side effects to be aware of

Some dogs may have more side effects than others, such as:

• Drowsiness

• Restlessness

• Vomiting

• Diarrhea

• Hypersalivation 

• Loss of appetite

An allergic reaction can even happen in response to the drug itself. That is rare, but contact your vet at once if you notice symptoms such as swelling, difficulty breathing, or hives. 

When you should avoid giving your dog Zyrtec

There are situations where dogs should not take Zyrtec: 

• Dogs with kidney or liver disease: These are the organs most active in metabolizing and excreting medications. If they are not working properly, drugs could accumulate dangerously. 

• Dogs taking other medications: Some drugs can interact with cetirizine, making it less effective or more dangerous. Talk to your vet about all the drugs your dog is already on.

• Pregnant or nursing dogs: Studies have not yet been done on the safety of giving Zyrtec to pregnant or nursing dogs.

• Dogs sensitive to antihistamines: Some dogs don’t tolerate antihistamines well and may develop severe side effects.

Never make assumptions about your dog’s ability to safely take Zyrtec; dogs process medications differently than humans.

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Bottom line

Zyrtec can be a helpful addition to your dog's medicine cabinet. It can help dogs with mild allergies and skin conditions. You have to make sure the dosage is precise and should only be given when monitored by a veterinarian. Use the correct formulation (plain cetirizine without pseudoephedrine) and watch closely for side effects. 

While Zyrtec is widely available over the counter, not every dog can safely take it. Your dog’s medical history and current symptoms make a difference, and your veterinarian should evaluate your dog. 

References:

• Banovic, Frane, et al. “Effect of Diphenhydramine and Cetirizine on Immediate and Late‐Phase Cutaneous Allergic Reactions in Healthy Dogs: A Randomized, Double‐Blinded Crossover Study.” Veterinary Dermatology, vol. 31, no. 4, 11 Feb. 2020, p. 256, https://onlinelibrary.wiley.com/doi/10.1111/vde.12840

• ‌Ekstrand, Carl, et al. “Cetirizine per Os: Exposure and Antihistamine Effect in the Dog.” Acta Veterinaria Scandinavica, vol. 60, no. 1, 26 Nov. 2018, https://actavetscand.biomedcentral.com/articles/10.1186/s13028-018-0431-3

• ‌Paterson, S. “Use of Antihistamines to Control Pruritus in Atopic Dogs.” Journal of Small Animal Practice, vol. 35, no. 8, Aug. 1994, pp. 415–419, https://onlinelibrary.wiley.com/doi/10.1111/j.1748-5827.1994.tb03867.x