Cetirizine (Reactine) Dosing for Dogs


Cetirizine is an antihistamine medication that can be used to treat allergic itching and other conditions in dogs. Generally, we find this type of medication is not particularly effective for most dogs, but because it's readily available over-the-counter in human pharmacies, and because it's relatively safe it's a reasonable starting point for mild cases. If you have used this medication and find it is not helping after a few days please talk to your veterinarian about more effective prescription options.

Adverse Effects

Ceritizine is well-tolerated by most dogs with short term use, but adverse effects can include drowsiness, vomiting, diarrhea and agitation. These and other adverse effects are more common with extended long-term use.

Dosing Formats

Cetirizine hydrochloride is most commonly sold under the brand name Reactine, but it's also available as a store-brand or generic drug.

The most commonly available sizes are as follows:

  • Regular strength tablets - 5 mg
  • Extra strength tablets - 10 mg
  • Please avoid any combination products that include other ingredients, and be sure to ask your pharmacist if you need help finding the right product.


All of the following doses are to be given orally, once every 24 hours. If you notice any adverse effects please discontinue the medication and contact your veterinarian.

Body Weight Regular Strength 5 mg Tablets Extra Strength 10 mg Tablets
1-5 kg 1 -
6-15 kg - 1
20-35 kg - 1.5
36-50 kg - 2

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