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Zyrtec for Dogs

By | Last Updated: 22nd February 2023

What is Zyrtec used for in dogs

Zyrtec (generic name cetirizine) is an antihistamine medication prescribed by veterinarians for the treatment of allergies in pets [1]. It is known as a second-generation antihistamine, useful for reducing allergic symptoms like itchy skin, swelling, irritation, coughing, or sneezing caused by atopic dermatitis in dogs and cats [1, 2].

It can also be administered for the treatment of allergic reactions triggered by a bee sting, external allergens like dust mites and pollen, and food allergy-induced diarrhea [10].

Some breeds including the Irish Setter, Dalmatian, Lhasa Apso, Golden Retriever, Terriers, Old English Sheepdog, and Bulldogs are more likely to suffer from allergic dermatitis [2]. These dogs may be given cetirizine pills to ease their severe itching and skin irritation. As compared to other antihistamines, such as Benadryl, dogs treated with Zyrtec exhibit a higher response rate [8].

Quick Information

Zyrtec for Dogs

Generic name: Cetirizine

Brand name: Zyrtec® [1]

Type: Second generation H1 receptor blocker [1]

Active Ingredients: Cetirizine hydrochloride [3]

Is it approved by FDA: No [1]

Availability: Prescription medication, extra-label drug sold over the counter [1]

Who can take it: Dogs, cats, humans [4]

Forms: 5 mg and 10 mg tablets, flavored pills, oral syrup [1, 5]

Cost: About $0.33 (per 10 mg tablet)

Can dogs take Zyrtec: Is it safe

Scientific studies have shown that Zyrtec is moderately effective and well tolerated in dogs with allergic skin conditions [4, 7]. However, do not give your dog Zyrtec-D, a decongestant containing pseudoephedrine as one of the active ingredients since it is toxic to dogs [9].

How does Zyrtec work in dogs

Histamine is an organic compound created by the dog’s immune system as part of an allergic response. It recognizes and binds to H1 and H2 histamine receptors, causing small blood vessels to expand thereby triggering symptoms like swelling and itching. Zyrtec, being an H1 receptor blocker, inhibits the effect of histamine on H1 receptors and helps in preventing the allergic symptoms [1, 6].

Zyrtec (Cetirizine) dosage for dogs: How much can you give

Give Zyrtec to your dog only after consulting a licensed vet. Since the exact dosage depends on your pet’s weight and the severity of its symptoms, be sure to follow the drug regimen as prescribed by the veterinarian.

As tablets, Cetirizine can be given by mouth with or without food [7]. The normal dosage is 1 mg of Zyrtec per kg (0.5 mg/lb) of your dog’s weight, given orally once or twice per day [1, 6]. Make sure to complete the full course of the medication unless otherwise instructed by the vet.

What to do in case of a missed dose

If you have forgotten to give a dose, give it as soon as possible. However, if it is time for the next scheduled dose, skip the missed dose altogether. Make sure that you never give two doses at the same time.

Signs of Zyrtec overdose

Rare instances of heavy sedation or excessive drowsiness have been observed in smaller dogs with long-term use of high amounts of Zyrtec [6, 9]. If you suspect an overdose, seek immediate veterinary attention.

Side effects of Zyrtec in dogs

Dogs on Zyrtec often exhibit the following side effects:

  • Hypersalivation or excessive drooling [2, 6]
  • Vomiting [2, 6]
  • Constipation (the dog is straining to poop with no fecal volume, discharging small amounts of mucus or hard and dry fecal material, having swelling and redness around its anal region) [2]
  • Urinary retention (the dog frequently trying to urinate without success, straining to urinate, licking its urinary opening, discharging blood in urine, or showing lethargy) [2]
  • Excitability [2]

Contact your vet immediately, if any of these side effects occur in your dog.

When should Zyrtec not be given to dogs

Always make sure to inform the vet about your pet’s medical history, as well as any medications you might already be giving it. Zyrtec is usually not recommended if:

  • Your dog has been affected by kidney problems or liver diseases [6]
  • It is pregnant or nursing [6]
  • The dog is allergic or has intolerance to antihistamines [6]
  • It is already on psychoactive drugs like Alprazolam, Ativan, and Diazepam [9]


    1. Cetirizine (Zyrtec®) for Dogs and Cats – Petplace.com
    2. Cetirizine Hydrochloride for Dogs – Vetinfo.com
    3. Zyrtec® Tablets – Zyrtec.com
    4. Why I love Zyrtec for pets (especially in cats) – Petmd.com
    5. Antihistamines for Dogs – Dogappy.com
    6. A Guide to Cetirizine–Zyrtec Generic Option – Petcarerx.com
    7. Treatment of canine atopic dermatitis with cetirizine, a second generation antihistamine: A single-blinded, placebo-controlled study – Ncbi.nlm.nih.gov
    8. Antihistamines for Dogs – Aahneenah.com
    9. Zyrtec For Dogs – Veterinaryplace.com
    10. Is Zyrtec Safe for Dogs – Smartdogowners.com

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