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Key takeaways
Hydroxyzine is an effective antihistamine for dogs, prescribed for allergic reactions, motion sickness, and allergic skin diseases like eczema. Its efficacy may vary depending on the cause of the allergy.
The medication can cause side effects such as sedation, dry mouth, constipation, and, in rare cases, excitability or seizures. Hydroxyzine should be given to your pet only as prescribed by a veterinarian.
Veterinarians may recommend hydroxyzine cautiously for dogs with certain health conditions. To avoid adverse reactions, inform your veterinarian of any other medications the dog takes.
Alternative treatments for dog allergies may include other antihistamines, newer-generation drugs, steroids, allergy shots, supplements, and lifestyle adjustments to reduce exposure to allergens.
Just like their human owners, some dogs have seasonal allergies. Others may be allergic to medications, food, or things they encounter out on their adventures—such as bee stings, snake bites, or other traumas that can cause a reaction. There are several over-the-counter and prescription medications that can help your furry friend in the case of an allergic reaction, one of which is hydroxyzine. Here we will go over hydroxyzine’s uses, dosage, side effects, and some safety considerations.
What is hydroxyzine?
In humans, hydroxyzine hydrochloride is used both as an antihistamine and as an anti-anxiety or sleep medication. Its primary function is blocking the effects of histamine in the body. Histamine is what gives us symptoms of an allergic reaction such as:
- Itching
- Swelling
- Watery eyes
- Rash or hives
- Sneezing
- Runny nose
By blocking histamine’s activity, some antihistamines also cause mild sedation. For this reason, humans and animals feel sleepy while taking antihistamines like hydroxyzine.
What is hydroxyzine used for in dogs?
Hydroxyzine can be prescribed to dogs for a number of reasons, including allergic reactions, motion sickness while traveling, and allergic skin disease such as eczema, also known as atopy when referring to dogs.
Allergies
When choosing which drug to give to a dog for an allergic reaction, veterinarians look to the cause of the allergy. Sara Ochoa DVM, a veterinarian at seniortailwaggers.com, says that hydroxyzine can be used for allergic reactions to snake bites, medication, or bee stings. Benadryl is also used, and many vets recommend it first, especially since many owners have it on hand or can get it easily.
“I [prescribe] hydroxyzine in cases where Benadryl does not seem to be helping,” Dr. Ochoa says.
As for seasonal allergies, hydroxyzine may not be prescribed as the first medication either. “Allergies in dogs are not largely histamine-mediated and therefore hydroxyzine does not work well for most allergic dogs,” says Jamie Whittenburg, DVM, a veterinarian at seniortailwaggers.com.
Atopic dermatitis
Hydroxyzine is often used for allergic skin conditions in dogs such as atopic dermatitis or atopy, also known as eczema. This chronic, itchy condition can cause great discomfort to dogs, much like it does for humans. The constant itching can cause dogs to open up wounds in their skin, making them susceptible to infection. Therefore, preventing itching and chewing is an important part of keeping your pet healthy.
You may notice your pet seems less anxious when taking an antihistamine, but it might also be because they are in less discomfort. The sedative effect “is also a great side effect to help dogs sleep a little better at night and not itch all night,” Dr. Ochoa says. When your pet will be sleeping better and not scratching or itching throughout the night, they are also giving themselves more time to heal.
Nausea and vomiting
Antihistamines are also antiemetic in dogs, meaning they treat vomiting associated with motion sickness. So, meds like hydroxyzine may be recommended before traveling for both this reason and their sedative or tranquilizing effects.
Because of its sedative effects, hydroxyzine could cause your pet to have sluggish movement, clumsiness, or be more prone to dozing. Keep this in mind when transporting your pet.
Hydroxyzine dosage for dogs
Unlike some other antihistamines, hydroxyzine is a prescription medication, so it should only be given at the dose and frequency prescribed by your veterinarian.
The typical dosage of hydroxyzine is 1 mg tablet per pound of body weight twice a day. You should follow the dosing instructions of one to two maximum mg per pound twice a day. The active ingredient, hydroxyzine, will work within three to six hours, most likely hitting its peak effectiveness around three hours. Some short-acting doses might work after an hour.
The medication may come in a pill or a liquid. You should discuss with your vet the best method for getting your pet to take the medication while taking into account your dog’s temperament around medications. You’ll also need to discuss the best time of day, if it should be taken with food, and any other health considerations or medications. Hydroxyzine should be stored at room temperature away from excess heat and moisture.
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Hydroxyzine for dogs side effects
As with all medications, hydroxyzine has several side effects. Common side effects of hydroxyzine include:
- Sedation or drowsiness
- Dry mouth, leading to increased drinking
- Constipation
- Lack of appetite
Excitability or hyperactivity is a rare side effect of the medication. And tremors or seizures are very rare.
Hydroxyzine is usually a short-acting medication and will clear the system within 24 hours.
If your dog is showing any of the following possible side effects, they may be responding poorly to the medication, it may be interacting with another of their medications, they may have overdosed, or they may be allergic to hydroxyzine. If you notice any of the following, seek emergency veterinary advice:
- Major behavior changes, such as being more energetic or significantly lethargic
- Vomiting or diarrhea
- Loss of consciousness
- Seizure
- Trouble breathing
Dr. Ochoa says to observe your pet closely when they start the new medication for signs that they are not tolerating it well. Ask your vet if you have concerns about any side effects noted.
Is hydroxyzine safe for dogs?
Veterinarians find hydroxyzine to be an effective antihistamine for dogs, and studies show it is a good option for dogs with eczema. Much like with people, not every drug works well for every dog or every condition, so you may need to work out a treatment plan with your vet.
One important consideration when planning out your dog’s best course of treatment is whether or not they are taking any other medications. If your pet is already on an anti-anxiety or sedative medication, the sedative effects of hydroxyzine could have a compounding effect.
“Your dog’s veterinarian should always be kept apprised of any medications your dog is taking so that adverse drug reactions may be avoided,” Dr. Whittenburg says. Include a list of any medications, vitamins, or supplements along with your pet’s health history when you visit your veterinarian.
Additionally, hydroxyzine should be used cautiously in pets that have glaucoma, high blood pressure, trouble urinating, enlarged prostate, intestinal blockages, and kidney or heart disease.
Alternative treatments
In addition to other antihistamines like Benadryl (diphenhydramine) or Zyrtec (cetirizine), your veterinarian might want you to try other medications for your dog’s allergies either before or after trying hydroxyzine.
“There are many newer generation drugs that work much better than hydroxyzine for dog allergies,” Dr. Whittenburg says.
Other pet medications veterinarians recommend for allergies in canines include Apoquel and Cytopoint. Apoquel is given in tablet form once a day while Cytopoint is a monthly injection.
Other medications your vet may try to help your pet’s allergies include steroids or allergy shots, sometimes called immunotherapy, something humans often also get to combat allergies long-term.
Some supplements are potentially helpful for dogs with allergies and eczema, but, again, do discuss any new vitamins or supplements with your vet before adding them into your pet’s diet. Coconut, fish, or other oils that make your pet’s hair and skin healthier might reduce itchiness.
You might also make lifestyle adjustments to help your dog, such as:
- Figuring out what is causing the irritation or allergy for your dog and eliminating it from your environment
- Adjusting your walk routine or route to avoid certain triggers
- Changing your household cleaning products
- Cleaning more thoroughly to eliminate dust or mold.
You might have to even give up your favorite perfume or laundry detergent if it’s exacerbating your pet’s allergies. Additionally, smoking is not good for a pet prone to allergies, so avoiding cigarettes will benefit your health and your pet’s. Ask your vet about recommended pet bathing products or procedures to help alleviate itchy skin and not open up any sensitive, healing wounds.