Zyrtec(®) with the active ingredient cetirizine is an antihistamine sometimes used to treat dermatitis, a condition which causes a dog’s skin to become itchy. It can be purchased over-the-counter and is tolerated well by most dogs. One of the main benefits of the medicine is that unlike most other popular antihistamines it rarely causes sedation.

Which form of Zyrtec should I use?

Make sure the formulation of Zyrtec you are using contains cetirizine as the only active ingredient. The decongestant formulation “Zyrtec-D” also contains pseudoepehedrine which is dangerous for dogs and should not be used. The active ingredients contained within each product are usually shown clearly on both the front and back of the packaging.

Safer Alternative:

Natural remedies offer our pets safe and effective relief from itching without having to risk the nasty side effects of traditional medicine. We recommend Derma-Ionx, a natural supplement suitable for dogs of all ages. Simply squirt the liquid into your dog’s mouth or dish to quickly and easily reduce the symptoms of skin irritation.

Recommended Dosage

Always speak to your vet for professional advice before giving Zyrtec to your dog and read the packaging carefully to make sure cetirizine is the only active ingredient.

For treating…


Atopic Dermatitis0.5 mg/lb every 24 hours
Allergic Dermatitis0.5 mg/lb every 12 hours

Some vets prefer treating atopic dermatitis with a total dose of 5 – 10 mg once daily. We recommend following the dosage recommendation of your own vet. This medicine can be given either with or without food.

Liquid Dosage:

Liquid Zyrtec is no longer being made, if you want a liquid medicine try Children’s Aller-Tec®. Children’s Aller-Tec® contains 1 mg/mL cetirizine which means it can be given to your dog at a dosage of 0.5 mL/lb. Use twice daily for allergic dermatitis and once daily for atopic dermatitis.

Example Dosage: A 50 lb dog with allergic dermatitis could be given 25 mg twice daily. The same dog with atopic dermatitis could be given 5 – 10 mg once daily, or 25 mg once daily.

Is It Safe For Use In Dogs?

Cetirizine has shown to be well tolerated by dogs, but based on its use in humans we recommend being cautious (or avoiding use completely) when treating dogs with liver or kidney problems. If your dog has severe liver or kidney problems you should try Omega-3 fish oils instead which improve the symptoms of itching in around 25% of dogs with atopic dermatitis.

Cetirizine does not cross the blood-brain barrier (a special shield that stops material in the blood from entering the brain) in large amounts which makes sedative effects rarer, but there is still a possibility.

Pregnant/Nursing Dogs: In trials pregnant dogs were given large amounts of cetirizine with no damage to the fetus, meaning it is probably safe for pregnant pets. The drug is passed in small amounts through milk, so it’s best to avoid giving it to a nursing dog.

Safety Guidelines For Use

Owners who are considering treating their dog with cetirizine should follow these safety guidelines:

  • Don’t give this medicine to your dog without speaking to the vet first
  • Only use formulations which contain ceitirizine as the only active ingredient
  • Be cautious or avoid use completely when treating dogs with kidney or liver disease
  • Look into natural remedies like Omega-3 for your pet’s itching

To avoid excessive sedation try not to give any medicines which depress the central nervous system to a dog who has taken this medicine. Medicines which depress the central nervous system includes benzodiazepines such as diazepam, alprazolam and ativan.

What Are The Uses?

Zyrtec (cetirizine) is used to treat itchy dogs with these conditions:

  • Allergic dermatitis
  • Atopic dermatitis

It is not often used to treat allergies which aren’t related to the skin. If your dog has a different type of allergy Benadryl® is usually a better choice, unless the sedative side effects are a concern.

Side Effects

Dogs who receive cetirizine could experience the following side effects:

Most Common

  • Vomiting
  • Salivation


  • Heavy sedation

Heavy sedation is rare but has been reported in smaller dogs when the medicine was used in high amounts.


Overdoses are unlikely to be dangerous considering that test animals were administered amounts up to 220 times higher than the human dose. Still, if you suspect your dog has taken an overdose you should call the vet immediately for advice. If your dog has taken a medicine which contains pseudoephedrine (for example Zyrtec-D) you should seek emergency veterinary attention. Just two pills (240 mg of pseudoephedrine) could kill a small dog.