The Side Effects of Hydroxyzine on Dogs

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Chocolate brown lab enjoying time outdoors without suffering from allergies.

Hydroxyzine is an antihistamine used to treat allergies in both dogs and cats. It is effective against respiratory irritation as well as itching from hives and rashes, making hydroxyzine a good option for both respiratory and topical allergies to plants and other chemical irritants. However, some dogs do experience side effects after taking this medication. Contact your veterinarian if any of these side effects appear serious.



Dizziness is a common side effect associated with hydroxyzine. The symptoms usually are mild and sometimes go away after your dog become acclimated to the medicine. However, if your dog is so dizzy that she is not able to stand up without falling over, call your veterinarian. There is a chance that she received too large a dose.


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Vomiting is also a known side effect of this drug. If your dog vomits after receiving hydroxyzine, he probably received too much mediation. Follow dosing instructions carefully. The medication specifies dosage based on the animal's weight.



Seizures are a rare but serious side effect of hydroxyzine. If your dog suffers a seizure after taking this medication it is most likely that she received an overdose or is having a bad reaction to the drug. If this happens, call your veterinarian or an emergency animal clinic immediately.




Some dogs experience a decreased appetite after taking hydroxyzine. This effect is typically mild, but if your dog takes this medication often and this occurs, he will begin to lose weight. A different medication or appetite stimulant may be needed. Talk to your veterinarian to determine the best combination of medicines to address both allergies and appetite.

Always check with your veterinarian before changing your pet’s diet, medication, or physical activity routines. This information is not a substitute for a vet’s opinion.




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