Hydroxyzine for Dogs: A Medication to Help Itchiness and Allergies
Key takeaways:
Hydroxyzine (Atarax, Vistaril) is an antihistamine medication that is commonly used to help with itchy skin and allergies in dogs.
All forms of hydroxyzine used to treat dogs are human products. If your dog is prescribed hydroxyzine, follow your veterinarian’s instructions carefully.
Over-the-counter hydroxyzine for humans often contains ingredients that may be toxic to dogs. Do not give your dog combination products that contain hydroxyzine.
Table of contents
If your dog has had itchy skin, runny eyes, or sneezing due to allergies, you may have wondered if you can treat their symptoms at home with antihistamines.
Hydroxyzine (Atarax, Vistaril) is an antihistamine that was originally created for humans. But it’s now also used off-label in dogs to manage seasonal allergies, acute allergic reactions, and motion sickness. Here’s what you need to know.
Hydroxyzine for dogs at a glance
Generic name | Hydroxyzine |
Common brand names | Atarax, Vistaril |
What it treats | Allergic reactions, itchy skin, motion sickness |
How it comes (forms) | Tablets, capsules, or oral liquid |
Standard dosage | Based on a dog’s weight |
Common side effects | Sedation, incoordination, tremors, overexcitement |
Average cost | $4-$11 for a 30-day supply of tablets |
What is hydroxyzine for dogs, and how does it work?
Hydroxyzine belongs to a class of medications called antihistamines. Allergies cause a chemical called histamine to be released in the body, which can result in itchy skin, redness, and swelling. Antihistamines like hydroxyzine work by blocking the release of histamine, which reduces these symptoms.
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What is hydroxyzine used for in dogs?
Hydroxyzine is FDA approved for use in humans. It is not officially approved for use in dogs. But if your veterinarian thinks it’s the best medication for your dog, hydroxyzine is OK for your dog to take.
Hydroxyzine is most commonly used in dogs to treat allergic reactions and itchy skin or eyes related to seasonal allergies. But it’s not 100% clear that hydroxyzine is a good option for dog allergies. Some studies say it’s an effective treatment, and others say it’s not.
Despite these mixed results, hydroxyzine can be given to your dog for mild allergies if your veterinarian thinks it’s the right choice. In dogs with more severe allergies, other medications or immunotherapy is typically needed to manage symptoms.
As mentioned, hydroxyzine can be used for motion sickness in dogs, though there are more effective treatments for nausea. Antihistamines like hydroxyzine are also used to treat itching due to mast cell tumors and acute allergic reactions related to insect stings.
Remember that dogs have different responses to antihistamines. You may need to work with your veterinarian to try a few different kinds to find what works for your dog.
What is the typical dosage of hydroxyzine for dogs, and how is it given?
The correct dosage of hydroxyzine for your dog will be based on their weight. Hydroxyzine is given to dogs by mouth in tablet, liquid, or capsule form. Oral hydroxyzine starts working in 1 to 2 hours, and its effects last for 8 to 12 hours.
Seasonal allergies: Many dogs develop seasonal allergies that lead to itchy skin. If this is your pup, here are some treatment options and management strategies to help them cope.
Allergy shots for dogs: Allergy shots are one possible treatment for dogs with allergies. If you’re considering this option, learn what to expect.
Flea prevention: Fleas can lead to an itchy dog, so it’s important to give your dog preventive flea medication. Take a look at the best flea medications for dogs.
Only give your dog the specific hydroxyzine product recommended by your veterinarian. Hydroxyzine is often combined with ingredients that can be toxic for dogs in over-the-counter human medications. Dogs should only take products that contain hydroxyzine as the single active ingredient.
Liquid forms of hydroxyzine must be shaken well before use and measured carefully. Your veterinarian or pharmacist can help by providing a measuring syringe.
Dogs usually take hydroxyzine for extended periods, sometimes for the rest of their lives. For maximum effectiveness, do not abruptly stop giving your dog hydroxyzine. To help prevent this, make sure to get your dog’s refills before you run out of medication.
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What should you do if your dog misses a dose of hydroxyzine?
If you forget to give your dog a dose of hydroxyzine, give them the medication as soon as you remember. But if it is close to the time for their next dose, skip the missed one and give them their dose at the regularly scheduled time. Do not double up or give your dog extra doses of hydroxyzine to make up for a missed one.
What are the common side effects of hydroxyzine in dogs?
All antihistamines, including hydroxyzine, can cause sleepiness and fatigue. This side effect will fade over time in most dogs who receive hydroxyzine long term.
For some dogs, hydroxyzine may also cause other side effects, including:
Dry mouth
Drooling
Upset stomach
Hyperexcitability
Giving your dog hydroxyzine with food may help reduce digestive side effects. And because hydroxyzine can cause dry mouth, make sure your dog has access to fresh water at all times.
Less common side effects of hydroxyzine in dogs include:
Muscle tremors
Low appetite
Low blood pressure
For hydroxyzine to work correctly and to minimize side effects, give it to your dog exactly as your veterinarian has prescribed.
What are the most serious risks of hydroxyzine for dogs?
Serious side effects of hydroxyzine are rare, but they do happen. Seizures are the most severe side effect reported in dogs. If your dog has a seizure after taking hydroxyzine, stop giving them the medication. Then, call your veterinarian or local emergency veterinary clinic for advice.
The biggest risk of hydroxyzine for dogs is overdose. Signs of a hydroxyzine overdose include:
Excessive sleepiness
Hyperexcitability
Loss of coordination or stumbling
Increased body temperature
Passing out
Seizures
If you know or suspect your dog has overdosed on hydroxyzine, contact your veterinarian, your local emergency clinic, or a pet poison hotline immediately for advice. You can reach the ASPCA Animal Poison Control Center at 1-888-426-4435 or the Pet Poison Helpline at 1-855-764-7661.
It’s recommended to discontinue treatment with hydroxyzine at least 2 weeks before a dog is tested for allergies. Hydroxyzine should also not be used or should be used with caution to treat the following types of dogs:
Dogs with a history of allergies to hydroxyzine or cetirizine
Working dogs, as hydroxyzine can cause sedation that will interfere with their work
Dogs who are pregnant or nursing
Dogs who are very old
Your veterinarian may also suggest avoiding hydroxyzine if your dog has a health condition such as:
A blocked bladder
A history of seizures
Thyroid disease
Glaucoma
Stomach blockages
Severe liver or kidney disease
An enlarged prostate
Does hydroxyzine interact with any other dog medications?
Yes, hydroxyzine can interact with other medications your dog may be taking. It should be used with caution in dogs that take the following medications:
Epinephrine
Central nervous system depressants such as diazepam (Valium) or alprazolam (Xanax)
Anticholinergic agents such as atropine or thorazine
Be sure to tell your veterinarian about any other medications — as well as any vitamins, supplements, or herbs — your dog takes.
Frequently asked questions
No, hydroxyzine and Benadryl (diphenhydramine) are two completely different medications. Though, they’re both antihistamines, and they can be used to treat similar issues in dogs, such as itchiness and other allergy symptoms.
Hydroxyzine is not typically used to manage anxiety in dogs, although it can have a mild sedative effect. If your dog has anxiety, speak with your veterinarian. Anxiety medications for dogs — like gabapentin or trazodone — may be a better option for your pup.
The bottom line
Hydroxyzine (Atarax, Vistaril) is an antihistamine that is used to manage itchy skin, allergic reactions, and motion sickness in dogs. Even though it is not FDA approved for use in dogs, veterinarians commonly prescribe hydroxyzine to dogs who have itching related to allergies. The most common side effect of hydroxyzine is drowsiness.
When giving your dog hydroxyzine, follow all of your vet’s instructions. And contact them if your dog has an adverse reaction to the medication.
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References
Bäumer, W., et al. (2011). Lack of preventing effect of systemically and topically administered histamine H(1) or H(4) receptor antagonists in a dog model of acute atopic dermatitis. Experimental Dermatology.
Brooks, W. (2021). Itch relief for dogs and cats. Veterinary Partner.
Brooks, W. (2024). Hydroxyzine (Atarax). Veterinary Partner.
Veterinary Information Network. (2019). Hydroxyzine (hydrochloride/pamoate) - Full version.
Zur, G., et al. (2002). Antihistamines in the management of canine atopic dermatitis: A retrospective study of 171 dogs (1992-1998). Veterinary Therapeutics.
