Cetirizine for Dogs

PetMD’s medications content is written and reviewed by veterinary professionals to answer common questions about how medications work, their side effects, and what species they are prescribed for. This content should not replace advice from your veterinarian. 

What Is Cetirizine Used for in Dogs?

Cetirizine is used to help manage symptoms of seasonal allergies in dogs.  

It’s available in single-ingredient tablets, combination-ingredient tablets, chew tabs, gel caps, oral syrup, and orally disintegrating tablets.   

Is Cetirizine FDA-Approved for Dogs? 

Cetirizine is currently not FDA-approved for use in dogs. However, it is commonly used in veterinary medicine, and veterinarians can legally prescribe certain human drugs for animals in specific circumstances. This is known as extra-label or off-label use because this use is not described on the drug label. 

Speak with your veterinarian about whether cetirizine is right for your pet.  

Compounded Cetirizine 

In certain circumstances, your veterinarian may recommend a compounded formulation of cetirizine. 

Compounded medications may be prescribed if there’s a specific reason your pet’s health can’t be managed by an FDA-approved drug, such as if:  

• Your pet has trouble taking the commercially available form  

• The required dosage strength is not available  

• The pet is allergic to an ingredient in the FDA-approved medication 

Compounded medications are not FDA-approved. They’re prepared by a veterinarian or licensed pharmacist on an individual basis to meet a pet’s specific needs. 

Cetirizine Considerations for Dogs

Only use cetirizine that is prescribed by your veterinarian for your dog.  

Cetirizine is FDA-approved for human use under the brand name Zyrtec, Zyrtec-D, and as generic cetirizine. ​Some formulations of ​Zyrtec may contain xylitol, which is toxic to dogs. 

Cetirizine should not be used in animals that are sensitive to the medication or other medications in the same antihistamine class, such as hydroxyzine.  

Giving cetirizine with certain medications can result in health risks to your pet, so it’s important to discuss your pet’s medical conditions and medications, including vitamins and supplements, with your veterinarian. 

How Does Cetirizine Work in Dogs?

When allergens are present, the immune system releases histamine, a chemical messenger that triggers allergy symptoms.  

As an antihistamine, cetirizine works by blocking histamine receptors, thereby preventing the release of histamine throughout the body. 

How Do You Give Cetirizine to Dogs?

Follow the directions on the drug label or as provided by your veterinarian. 

• Cetirizine can be given with or without food, but giving it with food can decrease the risk of digestive upset. 

• For liquid medication, wash your hands, wear gloves, shake the medication well, and slowly give your pet the medication.  

• Tablets can be given whole or crushed in food. 

What Happens If You Miss a Dose of Cetirizine? 

Speak with your veterinarian about what to do if a dose is missed.  

Generally, your vet may instruct you to give it when you remember, or if it’s almost time for your dog’s next dose, to skip the missed dose and resume your normal dosing schedule. 

Do not give extra or double doses. 

What Are the Side Effects of Cetirizine in Dogs?

Cetirizine is generally well-tolerated in dogs.  

Side effects are uncommon but may include: 

• Fatigue  

• Drooling 

• Vomiting   

Human Side Effects 

Humans should never take medication prescribed for pets, and pets should not be given medication prescribed for humans. Dosages often differ significantly. 

If you accidentally ingest a pet medication, seek medical attention or call Poison Control at 800-222-1222.  

Monitoring Your Pet 

No specific monitoring is required for this medication, but your veterinarian may recommend routine testing depending on your dog’s individual needs, other medications that may be prescribed, and/or the issue that initially caused your dog to be placed on this medication.  

When Should You Call Your Veterinarian? 

Call your veterinarian if you see any of the following, or if you have additional questions or concerns about the use of cetirizine: 

• Severe side effects occur  

• Your pet’s condition worsens or does not improve  

• You suspect an overdose 

What Happens If a Pet Overdoses on Cetirizine?

Overdoses of cetirizine are rare.  

However, signs of a cetirizine overdose may include:  

• Hyperactivity 

• Agitation 

• Vomiting 

• Sleepiness 

• Dilated pupils 

• Diarrhea 

• Elevated heart rate  

Overdoses of cetirizine products that contain pseudoephedrine, such as Zyrtec-D for humans, can be serious. 

If you suspect an overdose, seek emergency veterinary care or contact an animal poison control center (consultation fees may apply): 

• Pet Poison Helpline: 855-764-7661 

• ASPCA Animal Poison Control: 888-426-4435 

How Should Cetirizine Be Stored for Dogs?

Keep the following storage tips in mind for this medication: 

• Cetirizine should be stored at controlled temperatures from 68–77 F (20–25 C). 

• Keep the container tightly closed to protect its contents from moisture and light.  

• Compounded medications should be stored according to the compounding pharmacy’s label. 

• Keep out of reach of children and pets.