Hydroxyzine Hydrochloride (HCI), otherwise known as Anxanil, Atarax or Anxanil is an antihistamine that helps treat allergic reactions in dogs.
Some of the things It is used for include:
- atopic dermatitis
- insect bites
- snake bites
- vaccine reactions
- and other causes that result in skin inflammation. 
Ahead we dig deeper into this medication and how it helps our canine buddies.
Allergies in dogs
Similar to humans, dogs can be allergic to various substances,  including dog food, plant particles, and allergens in the air. Allergens are substances that, when inhaled or absorbed through the dog’s skin, respiratory tract or gastrointestinal tract, can cause inflammation.
Studies show that less than 10% of dogs are thought to be genetically predisposed to a sensitivity of allergens in our homes. The onset of airborne allergies in dogs is believed to begin between the ages of six months and three years.
Dog food allergies
Dog food allergies  are less common in dogs than airborne allergies. Although the symptoms of food allergies are similar to those of airborne allergies, the intensity of the itching is the same in both cases.
Dogs can develop food allergies at any age. The only reliable way to check for food allergies is by eliminating certain food products, or by changing diets to a grain-free diet with a veterinarian’s recommendation. When switching dog food diets, it’s best to maintain a high-quality, balanced and nutritionally complete diet.
Dogs may be allergic to one specific ingredient. The food elimination diet trial will help confirm if a food allergy exists.
Dogs are most often allergic to chicken, beef, corn, eggs, wheat, milk and soy products. Once you and your veterinarian have identified which ingredient is the offending allergen, he will recommend that this be avoided in future. Hydroxyzine HCI may be prescribed to help lessen the symptoms of the food allergy.
Food allergy symptoms such as:
- excessive itching
- chronic ear inflammation
- gastrointestinal problems
- chronic diarrhea
- constant gas
- licking feet
- itchy rear end.
An airborne allergy is an over-reaction or hypersensitivity of the immune system to a particular substance or allergen.
Dogs with these types of allergies develop a hypersensitive reaction to substances such as pollens and flea saliva. Your dog might present with one or more allergy indications.
Airborne allergy indicators:
- itching of the face, feet, ears, front legs, and stomach area
- all over body scratching
- secondary wounds which include scabbing, infection and hair loss
- licking and chewing of paws, and rubbing face and eyes with paws. 
As always, it’s best to consult with your veterinarian if your dog is showing these symptoms. Allergy testing will most likely be recommended, along with a good management plan that has a few treatment options.
Your veterinarian might prescribe anti-itch medication and antibiotics during the first phase of treatment. Hydroxyzine HCI use may be advised for seasonal flare-ups. An additional benefit of Hydroxyzine is that it might also help an insomniac pup get a good night’s rest.
What is Hydroxyzine for dogs?
This medication works as an anti-nausea, sedative, and anti-anxiety medication, and also has anesthetic properties. It is administered either as a tablet, capsule or oral liquid. Hydroxyzine HCI has fewer side effects than corticosteroids.
This medication does not treat or cure a condition but helps in the relief of itching for conditions like flea bite dermatitis. It has not been FDA approved for animals. It starts working 25 minutes after oral administration.
That said, a few days of therapy are needed for this medication to achieve its full effect. Hydroxyzine HCI is the active ingredient in all three  of these antihistamines:
How does hydroxyzine HCI work?
As mentioned, Hydroxyzine HCI is an antihistamine that relieves things like:
- and hot spots.
It works by reducing activity in the central nervous system. Antihistamine medications work by stopping histamines, and Hydroxyzine HCI blocks a histamine receptor called the H1 receptor. 
Histamines are produced in the body when there are allergens, and travel through the bloodstream. They then connect with the histamine receptors.
Watch as Dr. Kathy Hillestad gives more clarity on this drug:
Hydroxyzine dosage for dogs
Hydroxyzine HCI tablets are available by veterinary prescription for dogs. A typical dose is 1 mg per pound in dogs every 6-8 hours.
The medication is available in tablet form in the following doses:
- 10 mg
- 25 mg
- and 50 mg.
The capsules come in the following dosages:
- 25 mg
- 50 mg
- and 100 mg.
This medication is short-lived, so it may need to be given up to three times per day.
What if you missed a dose?
If you should accidentally miss a dose, give it as soon as possible. If the timing is too close to the next scheduled amount, skip the missed dose and continue with the regular schedule. Never double up on a dose.
Possible drug interactions
Consult with your vet regarding any other meds that your pup may be on. He or she will probably not prescribe Hydroxyzine if your dog is already taking any of these drugs:
- All monoamine oxidase inhibitors
- CNS depressants
- Anti-wheezing medications
Additionally, Hydroxyzine HCI cannot be given to dogs that are hypersensitive or allergic to hydroxyzine or medicines that are similar.  This drug should never be prescribed for dogs that suffer from the following conditions:
- heart disease
- enlarged prostate
- severe cardiac failure
- obstruction of the urinary bladder (problems urinating).
- obstruction of the pylorus (junction between the stomach and intestine).
- pregnant or lactating dogs
- working dogs like police or military dogs, seeing eye dogs, search-and-rescue dogs, hearing dogs
- nursing dogs and their pups.
It’s also important to keep your dog’s skin and coat clean and to use organic and natural shampoos and conditioning treatments containing Aloe Vera juices, avocado oils, and ingredients like refined shea and mango butter. These work wonderfully on dry coats and assist the skin and coat to recover fully.
Side effects of Hydroxyzine for dogs
As with all meds you give to your furry companion, Hydroxyzine comes with its own set of side effects , and you should keep a close lookout for any of the following symptoms:
- increased urination
- trouble urinating
- dry mouth
- change in behavior.
Don’t forget that you and your vet are in this together, so should you notice anything out of the ordinary, it’s best to consult with them over a phone call or a quick visit; just to ensure things go as smooth as they possibly can.
Final thoughts on medicating with Hydroxyzine HCI
Whether your dog is suffering from hives, itchiness or skin rashes, a good veterinarian can help you deal with these issues. Hydroxyzine HCI is helpful for the relief of itchiness, and should only be administered after consulting with your veterinarian.
All dogs will respond in different ways to antihistamines. As a pet parent, you will need to always discuss with your vet any medications that your dog is already taking.
As usual, it’s important to always read the label of all medications, and administer the correct dose as directed. Keep in mind that that resolving dermatitis requires that your veterinarian identify the underlying causes. Your vet may also need to treat secondary infections or any other complications.
Looking for other dog meds?
- Fluoxetine for depression and behavioral problems.
- Famotidine for gastric ulcers.
- Atopica for chronic itchiness and skin allergies.
- Simparica for tick and flea control.
- Benadryl for allergies.
- Tramadol for mild to moderate pain relief.
- Clavamox for bacterial infections.
- Deramaxx for chronic pain and inflammation.
- Eichenseer, M et al. “Efficacy of dimetinden and hydroxyzine/chlorpheniramine in atopic dogs: a randomised, controlled, double-blinded trial” Veterinary record vol. 173,17 (2013): 423.
- Drug record: Hydroxyzine- National Institutes of Health
- Hakanen, Emma et al. “Urban environment predisposes dogs and their owners to allergic symptoms” Scientific reports vol. 8,1 1585. 25 Jan. 2018, doi:10.1038/s41598-018-19953-3
- Hydroxyzine hydrochloride – PubChem
- Chan, Sanny K and Donald Y M Leung. “Dog and Cat Allergies: Current State of Diagnostic Approaches and Challenges” Allergy, asthma & immunology research vol. 10,2 (2018): 97-105.
- “Food allergy in dogs and cats: a review.” A. Verlinden. M. Hesta. S. Millet. G.P. Janssens. 2006
- Hydroxyzine – ToxNet
- Olivry, Thierry et al. “Treatment of canine atopic dermatitis: 2015 updated guidelines from the International Committee on Allergic Diseases of Animals (ICADA)” BMC veterinary research vol. 11 210. 16 Aug. 2015, doi:10.1186/s12917-015-0514-6