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Key takeaways
Zyrtec (cetirizine hydrochloride) is an over-the-counter antihistamine approved for humans. It can also treat dogs’ allergies to alleviate symptoms like itching, sneezing, and watery eyes.
Unlike Benadryl, Zyrtec is a second-generation antihistamine that is less likely to cause drowsiness in dogs. Still, it’s crucial to consult a vet for the correct dosage and to check for drug interactions.
The standard dosage for Zyrtec in dogs is 1 mg per 2.2 pounds of body weight, administered once every 24 hours. The vet considers the dog’s health, weight, and allergy severity before prescribing.
Zyrtec is generally safe for dogs at the correct dosage. However, Zyrtec-D should be avoided due to its pseudoephedrine content, which can be harmful to dogs. Untreated dog allergies can lead to serious health issues.
Does your dog constantly scratch its neck or gnaw at its legs? It could be a sign they have an itch caused by an allergic reaction to grass, mold, dust mites, an insect bite, or another source. Giving your dog Zyrtec may help ease your its itchy skin and other symptoms.
If you experience seasonal allergies, you know what kind of relief your go-to allergy medication provides. But that doesn’t mean you can share your meds with your pup. Read on to learn more about how the allergy remedy for your dog works and what vets recommend.
What is Zyrtec used for in dogs?
Zyrtec (cetirizine hydrochloride) is a brand-name over-the-counter (OTC) second-generation antihistamine approved by the U.S. Food and Drug Administration (FDA) for use in humans—but it works similarly in dogs. It helps block allergy symptoms, such as sneezing, itching, and watery eyes, caused by histamine, a chemical the immune system releases in response to allergens.
“Zyrtec can help reduce the allergic response and provide relief for the dog,” says Sara Ochoa, DVM, a veterinarian at Animal Hospital in West Monroe, Louisiana, and cofounder of the pet resource site How To Pets. “Dogs can have allergic reactions to various allergens such as pollen, dust mites, mold, and certain foods.”
You may notice your pet has allergies because they are scratching, licking, biting, or rubbing excessively on certain areas of their body or have red or inflamed skin. Zyrtec is commonly used in dogs to ease itching from:
- Allergic reactions
- Atopic dermatitis, a condition characterized by itchy and inflamed skin
- Flea allergies
- Hives
- Stings
Even though Zyrtec is available over-the-counter and generally considered safe, you should speak with your pet’s veterinarian before administering it. They will take into account your dog’s pre-existing health conditions as well as any other medications or supplements they take.
Is Zyrtec the same as Benadryl for dogs?
Zyrtec and Benadryl are both antihistamines, but they contain different active ingredient: Zyrtec’s active ingredient is cetirizine hydrochloride while Benadryl’s is diphenhydramine.
Both Zyrtec and Benadryl are available as over-the-counter medications—and can be given to dogs under a veterinarian’s supervision. However, as a “first-generation” antihistamine, Benadryl crosses the blood vessels (blood-brain barrier) in the central nervous system, and can cause drowsiness. Zyrtec is a second-generation antihistamine, which doesn’t cross the blood-brain barrier to the same degree, and is less likely to cause drowsiness.
“Vets have the knowledge and expertise to determine the appropriate dosage and form of Zyrtec for dogs based on their individual needs and health conditions,” says Dr. Ochoa. They can further inform you about any possible drug interactions with other medications, so you can take precautions.
Zyrtec dosage for dogs
The FDA hasn’t approved Zyrtec for treating allergies in dogs, so there is no dog-specific Zyrtec product available. You may be able to give your dog the same OTC Zyrtec product you’d buy for yourself at the drugstore—but you’ll need to speak with your vet first, so they can confirm an appropriate canine-specific dose.
“Zyrtec should be used under the guidance of a veterinarian who can determine the appropriate dosage and duration of treatment for your dog,” Dr. Ochoa says.
When considering the correct dose of Zyrtec for dogs, your veterinarian will consider your dog’s weight. The dose also depends on the cause of the allergy or itching, the dog’s overall health, symptom severity, and the form of Zyrtec given. Zyrtec is available in 5 mg tablets and 10 mg tablets or as a syrup.
The standard dose recommendation for dogs is 1 mg of Zyrtec per 2.2 pounds of your dog’s body weight. Zyrtec tablets are small, so for doses under 5 mg, it may be easier to use the syrup formulation.
Zyrtec is a fast-acting medication. It typically starts working within an hour of dosing. Dosage times are every 24 hours.
Zyrtec side effects for dogs
Unlike Benadryl, which has a sedative effect, Zyrtec isn’t as likely to make your dog sleepy. However some small dogs may experience some drowsiness depending on the dosage given. The possible side effects of Zyrtec for dogs include:
- Excessive salivation
- Vomiting
- Diarrhea
- Hyperactivity
Zyrtec typically remains in a dog’s system for no longer than 24 hours. If your dog has kidney or liver disease, it may take longer for their body to completely eliminate the medication. If side effects last longer than 24 hours, consult your veterinarian. They can recommend another antihistamine medication that might not have the same side effects.
Zyrtec interactions
It’s important to let your veterinarian know all other medications and supplements your pup is taking, to avoid harmful interactions. Zyrtec may have adverse reactions with other medications, including the following:
- Central nervous system depressants, such as opioids (codeine, hydrocodone), benzodiazepines (alprazolam, lorazepam), or muscle relaxants (carisoprodol, cyclobenzaprine(MAOIs), and tricyclics
- Other antihistamines
“If your dog is taking Zyrtec or any other medication, it’s important to monitor them closely for any signs of adverse reactions,” says Maria Baker, DVM, a veterinarian at Veterinary Emergency Group in Montclair, New Jersey, and founder of pet resource pet-how.com. “This includes watching for any changes in behavior, appetite, or activity level, as well as monitoring for any unusual symptoms or side effects.”
Is Zyrtec safe for dogs?
Regular Zyrtec is generally safe for dogs at the proper dosage, but Zyrtec-D is not.
“Zyrtec-D can be dangerous for dogs because it contains a decongestant called pseudoephedrine,” Dr. Ochoa says. “Decongestants can be harmful to dogs due to their stimulant effects, which can lead to increased heart rate and elevated blood pressure.”
Recent scientific research on the effectiveness of cetirizine (the active ingredient in Zyrtec) for dogs is sparse. One study published in the journal Veterinary Dermatology found that cetirizine reduced skin allergic symptoms in dogs “significantly.”
But a separate study published in the journal Veterinary Sciences found that 1 mg to 3 mg of cetirizine was “poorly effective” in reducing symptoms. In that study, cetirizine fared no better than the placebo for relieving allergy symptoms in dogs.
6 risks for leaving dog allergies untreated
“Chronic itching, pain, and discomfort from untreated allergies can significantly reduce a dog’s quality of life,” says Dr. Ochoa. “They may become lethargic, lose interest in activities, and experience overall decreased well-being.”
Your dog can’t tell you they’re suffering—but it’s important to pay attention and work with your vet to treat their symptoms, because if left untreated, your dog’s allergies could develop into the following health conditions.
- Chronic ear infections: Because allergies can affect your dog’s ears, it can lead to chronic ear infections, according to Dr. Ochoa. “Constant itching and inflammation can cause your dog’s ears to become warm, red, and extremely painful,” she says. Without treatment, your dog may experience persistent or recurrent infection that could lead to hearing loss or even long-term ear damage.
- Digestive issues: Untreated allergies can cause vomiting, diarrhea, and poor nutrient absorption. “Persistent gastrointestinal issues can result in weight loss, malnutrition, and overall weakness if not addressed promptly,” Dr. Ochoa explains.
- Respiratory problems: In addition to congestion and difficulty breathing, severe cases of dog allergies can lead to asthma-like symptoms.
- Behavioral changes: ”Constant itching and discomfort can lead to mood swings, irritability, and restlessness,” Dr. Ochoa says. This could be further impacted by your pet having a hard time sleeping. Extended periods of this discomfort could eventually manifest as aggression.
- Bacterial or yeast skin infections: When man’s best friend itches, he scratches his skin. Repeated skin irritation could lead to infections when not treated.
- Eye infections: Similar to in humans, allergy can cause itchy and watery eyes. When your pup scratches at its eyes, it can lead to unintended infections.
“It’s important to work with a veterinarian to determine the underlying cause of your dog’s symptoms, as different conditions may require different treatment approaches,” Dr. Baker recommends. She warns that ignoring “the root cause” could leave your pet’s discomfort unresolved.
Bottom line: Zyrtec for dogs may reduce allergy symptoms
When given at the proper dose, Zyrtec may relieve your dog’s itching and other allergy symptoms. Don’t use Zyrtec-D, which can be dangerous for your dog, and talk to your veterinarian before giving your dog Zyrtec. They may want to examine your dog to rule out underlying causes of allergy symptoms.