How long for dog cetirizine to work on environmental allergies?

Antihistamines, like cetirizine, don't often work well in dogs. It is worth a try to use them but dogs metabolize them so quickly they just don't have the effect you would expect in most cases. Also, remember, if his scratching is not due to an allergy then that may be why it is not working. After 4 hours you should have noticed it working already.

Yes, you can give cetirizine as needed. Be aware that if you use it constantly there is a chance he will become tolerant to it and will no longer work. It should also not be used in animals that have any underlying kidney or liver disease. Please review this article on the medication in regards to dosing, side effects, etc. ( https://www.petcoach.co/pet-medication/cetirizine/ )

It should begin to work within a couple hours of administration. The half life allows for once daily dosing in cats. That said, not all antihistamines are effective in every cat. You must find the one that is most effective for your cat.

Your dog could definitely have environmental allergies! Most people do not have much luck with these drugs as they are antihistamines, and as such are not very effective for these kinds of allergies in dogs. However, they tend to be very safe and very inexpensive, so I sometimes start with antihistamines if the itching is very mild and the dog does not seem miserable. Also, I have had great success with the oral pill Apoquel for some allergies as well, and this is a medication that is much safer to use long-term than steroids like prednisone. There is also an an allergy injection called Cytopoint that is very safe and works well for some dogs with seasonal allergies. Ask your veterinarian for his/her recommendation for your particular situation. Hope that helps!

Dogs around 10 pounds in weight should only get a half tab once per day. If the Zyrtec doesn't seem to be working, or seems to wear off too quickly, I would contact Hope's vet. It may be time to switch to a stronger medication, or try a different OTC such as Claritin to see if it is better for longer-term control of Hope's allergies.

Most OTC antihistamines can be used in dogs; however you should never give any medications to your dog without the advice of your veterinarian. Allergies can be frustrating to diagnose since they can have multiple causes (inhaled, food, contact). Schedule an appointment with your veterinarian. Discuss food elimination trials and allergy testing and if antihistamine use is indicated, he or she can give you a proper dose, The medication may provide some relief but your task is to try to determine what your dog is allergic to and decrease or eliminate it. Monitor her for side effects including lethargy and weakness, and if you see those signs, have her seen by a vet right away. Best of luck.

Hi and thanks for posting on Petco Pet Education Center, formerly Petcoach! Cetirizine is an antihistamine that can be used to help lessen seasonal allergy symptoms. It is sometimes used in dogs with some efficacy- works for some dogs and not so well for others. Please be sure to obtain all dosing information for this drug from Barney's veterinarian. I hope this helps!