What Allergy Medicine is Safe for Dogs?

Matthew Nesbitt
By Matthew Nesbitt, Journalist specialized in animal research. Updated: March 21, 2024
What Allergy Medicine is Safe for Dogs?

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Many people associate allergies and dogs with the effects they have on humans. Too few are considerate of the fact dogs can have their own allergy problems. While allergies can be infuriating for anyone, humans are able to go to a pharmacy and buy over-the-counter medication to help combat daily inconvenience. For this reason, many people wonder what allergy medicine is safe for dogs? Are we able to buy over-the-counter dog allergy medicine? Do we need a prescription?

We answer these questions in this AnimalWised article. We do so by looking at different types of canine allergy medications, with a particular focus on antihistamines. We also look at one of the most common considerations in terms of whether human allergy medication is safe for dogs.

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  1. What are the different types of allergy medications for dogs?
  2. How to treat severe allergic reactions in dogs
  3. Antihistamine brands for dogs
  4. Can I give over-the-counter allergy medicine to my dog?
  5. Side effects of allergy medicine in dogs

What are the different types of allergy medications for dogs?

There are different types of allergy medicine for dogs, in part because there are different allergies from which they can suffer. An allergy is a disease whereby the dog's immune system is hypersensitive to a certain substance, causing it to overreact. The types of material which cause an allergic reaction are varied. Commonly they include:

The type of allergy medication will also depend on the severity of the symptoms. For humans, the major form of allergy medicine is antihistamine, usually taken in pill form. Antihistamines help to reduce everyday symptoms such as a runny nose, sneezing, hives or other allergic reactions. They work by contravening histamine receptors which are part of the reason why the immune system reacts. Generally they are best for short-term symptoms. Other allergy medicines for dogs include:

  • Antihistamines
  • Corticoteroids or other anti-inflammatory drugs
  • Immunotherapy injections
  • Steroid treatments
  • Medicated shampoo

While antihistamines are commonly used in human medicine, they are not as prevalent in veterinary practice. This is due to questions over their efficacy. Some reports claim certain antihistamines such as cetirizine do have some positive histamine-related inflammation, but additional clinical studies need to be carried out[1]. They should only be administered when the veterinarian recommends it.

Generally, veterinarians will prescribe corticosteroids, with antihistamines prescribed when mild pruritus (pustules) persists. It has been shown that antihistamines have shown efficacy against atopic dermatitis when they are combined with omega-3 and omega-6 fatty acids.They may also prove effective against gastrointestinal ulcers.

For food allergies, the most effective treatment is to remove the food from the dog's diet. However, a veterinarian may also prescribe a specific diet to help counteract allergens. This is usually carried out after an elimination diet. This is when the diet is methodically altered to determine which allergen is causing the reaction. It is a trial and error tactic which can be prolonged.

Medicated shampoo is used for allergic reactions on the dog's skin. These are often used to treat contact dermatitis, a reaction to various external materials which irritate the dog's skin. Inflammation, redness and even pus can occur as a result of this reaction. Medicated shampoos help to combat this problem as well as ensure overall hygiene.

How to treat severe allergic reactions in dogs

A severe allergic reaction in dogs is known as anaphylaxis or going into an anaphylactic shock. While all allergens cause a reaction in a susceptible animal, if the animal is particularly sensitive the reaction can threaten their lives. Anaphylaxis only occurs when the dog has been exposed to the allergen before. For example, if they have a medication allergy, the dog's immune system will recognize it and over-produce antibodies.

The symptoms of anaphylaxis in dogs will vary according to how they came in contact with the allergen, e.g. contact, ingestion, inhalation, etc. They include:

  • Severe swelling (often of the face)
  • Excessive drooling
  • Vomiting
  • Diarrhea
  • Difficulty breathing
  • Hives

Antihistamines combined with corticosteroids may be prescribed in mild cases of canine anaphylaxis. However, the most important thing is to first stabilize the dog. Whatever the cause of the reaction, the substance needs to be removed as much as possible. For example, if it is caused by ingestion, the dog may have their stomach pumped. The allergy medicine used to treat anaphylaxis are usually emergency drugs such as epinephrine, atropine or aminophylline. A combination of these and/or corticosteroids may be used.

Once the dog is stable, they will need to be monitored for changes and progress. This is why it is vital you take your dog to the veterinarian if they suffer a severe allergic reaction. An insufficient response time may result in a fatality.

What Allergy Medicine is Safe for Dogs? - How to treat severe allergic reactions in dogs

Antihistamine brands for dogs

There are various antihistamine brands on the market for humans, but most are not suitable for dogs. Also, while the active ingredients in these various allergy medicines for dogs are the same, name brands and formulae differ according to the market.

Not all types of antihistamine will work for dogs. While ebastine has shown positive results in humans, it has seen poor results in dogs[2]. Similar findings apply to polaramine. However, the second generation antihistamine loratadine does appear to offer better results. Some other antihistamines have been noted for positive use in dogs:

  • Diphenhydramine
  • Hydroxyzine
  • Cetirizine
  • Terfenadine

Likewise, clemastine or tavegil and the combination of first-generation chlorpheniramine and hydroxyzine and oxatomide among the second-generation antihistamines have been shown to control pruritus. It is always possible there will be new allergy medicine for dogs on the market, but it is very important we do not guess which will work for our dog.

Can I give over-the-counter allergy medicine to my dog?

We should not give over-the-counter allergy medication to dogs. This is for various reasons. Firstly, the veterinarian will need to ensure the symptoms we see are indeed due to an allergic reaction. They will know the clinical picture of the animal and know the best course of treatment.

Secondly, not all allergy medications are the same. For example, Benadryl is one of the most common antihistamine brands in the world. However, the active ingredients can change according to both product and region. For example, in the USA, diphenhydramine is most common, whereas cetirzine is more often used in the UK.

Hydroxyzine is often sold under the brand name Atarax, but many of the products contain other ingredients. This is why you should never give human medication to dogs. Not only may the dosages be incorrect, but the other ingredients may be toxic to the dog. This all presupposes that antihistamines are the correct type of treatment. Only provide antihistamines if given a prescription by a qualified veterinarian.

Another reason not to give over-the-counter drugs to a dog is due to dosage. The dosage of antihistamines and other allergy medications will vary. It will depend on the weight of the dog, the type of active ingredient and the severity of the allergy, among other factors. The administration information will be provided with the prescription as some may only need to be taken once a day, others more or less.

What Allergy Medicine is Safe for Dogs? - Can I give over-the-counter allergy medicine to my dog?

Side effects of allergy medicine in dogs

Adverse reactions from antihistamines are rare if prescribed by a veterinarian. As long as we follow the recommended dosage and follow the administration schedule, they should be relatively safe. Although side effects are rare, they can occur to varying degrees. They can include:

  • Drowsiness
  • Gastrointestinal disorders
  • Tremors
  • Lack of coordination
  • Hypersalivation
  • Excessive panting
  • Nervousness
  • Cardiac problems

Although antihistamines are relatively safe, we need to keep our dog in observation after at least the first two administrations. If we see any signs of side-effects, we should take the dog to the veterinarian. For corticosteroids, adverse reactions may also include increased thirst and appetite, lethargy or incontinence. Again, go to the vet if any of these occur.

This article is purely informative. AnimalWised does not have the authority to prescribe any veterinary treatment or create a diagnosis. We invite you to take your pet to the veterinarian if they are suffering from any condition or pain.

If you want to read similar articles to What Allergy Medicine is Safe for Dogs?, we recommend you visit our Medicine category.


1. Ekstrand, C., et al. (2018). Cetirizine Per Os: Exposure and Antihistamine Effect in the Dog. Acta Veterinaria Scandinavica, 60, 77.

2. Matsuda, M., et al. (1994). Comparative Pharmacokinetics of the Histamine H1-Receptor Antagonist Ebastine and its Active Metabolite Carebastine in Rats, Guinea Pigs, Dogs and Monkeys. Arzneimittelforschung, 44(1), 55-59.


1. Bravo, V., Martorell, A. M., & González, J. L. (2011). Therapeutic Pptions for Canine Atopic Dermatitis. Retrieved on January 24, 2020, from

2. Veterinary Portal. (2001). Allergic Diseases in Canines. Retrieved on January 24, 2020, from

3. Dominguez, J. A. (2015) Atopy in Pets. Retrieved on January 24, 2020, from

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What Allergy Medicine is Safe for Dogs?