What is cetirizine? 

Cetirizine (brand name Zyrtec®, Reactine®) is an antihistamine used to treat pruritus (itching) associated with atopic dermatitis, urticaria (hives), and insect-bite reactions in cats and dogs.

Its use is in cats and dogs is ‘off label’ or ‘extra label’. Many drugs are commonly prescribed for off label use in veterinary medicine. In these instances, follow your veterinarian’s directions and cautions very carefully.

How cetirizine given?

Cetirizine is give by mouth in the form of a tablet, or as an oral syrup. It may be given with or without food. If your pet acts sick or vomits after receiving the medication, try giving it with a small amount of food.

This medication will take effect quickly, in about 1 to 2 hours, and improvement of your pet's signs should follow.

What if I miss giving my pet the medication?

If your pet is receiving cetirizine twice a day and you miss a dose, give the next dose when it is time to do so.

If you are giving the medication once a day, give it when you remember and continue giving the medication at the regular time.

Never give your pet two doses at once or give extra doses.

Are there any potential side effects?

Cetirizine does not typically cause any side effects. Vomiting and increased salivation has been observed in some dogs. At high doses, sleepiness has been reported in small dogs and cats. Any side effects that are severe or worsen should be reported to your veterinarian.

This short-acting medication should stop working within 24 hours, although effects can be longer in pets with liver or kidney disease.

Are there any risk factors for this medication?

DO NOT use the combination product containing pseudoephedrine in dogs and cats.

• Cetirizine should not be used in patients that have a hypersensitivity to it or to hydroxyzine.

• You should use cetirizine with caution in pets:

• with a seizure disorder

• with difficulties urinating or appear to be constipated

• with thyroid problems, prostatic enlargement, or with heart, kidney, or liver disease

• with glaucoma

Doses: Standard Dog and Cat Doses are 5mg/10lbs of body weight given once daily.

The tablets are typically 10mg, so 1/2 tab for a 10lb dog or cat

Many dog parents are finding it to be he most effective antihistamine, given when there are allergy flare ups.

It seems to be more effective in combination with the Essential Fatty Acids ( ie Krill)