Yes, dogs can have certain antihistamine tablets, but only under the guidance and direction of a veterinarian. Human medications can contain ingredients, such as decongestants or xylitol (an artificial sweetener), that are toxic and potentially fatal to dogs.
Telfast®- (active ingredient fexofenadine ) these are available in 60 to 180 mg tabs. But note that while not likely to overdose, the dosage for most dogs is only 5-10 mg / Kg once or twice a day.
Loratadine (Claritin): ¼ mg per pound (half of a 10mg tablet per 20 lbs) once daily. Clemastine (Tavist-1, Antihist-1): 0.02mg per pound (one 1.34mg tablet per 65lb dog) twice daily. Diphenhydramine (Benadryl): 1mg per pound (one 25mg tablet for a 25lb dog) twice daily.
For this reason we recommend a consultation with our vets to discuss how to best manage their symptoms. If a visit to us is not possible you can try dosing your pet with a human antihistamine – we would recommend Zyrtec at a dose of 10mg per 10kg daily.
According to the Merck Veterinary Manual, the standard dose for Benadryl is 2–4 milligrams per kilogram of body weight, or 0.9–1.8 milligrams (mg) of Benadryl per pound. Therefore, a simple and practical dose is 1 mg of Benadryl per pound of your dog's weight, given two to three times a day.
Other antihistamines safe for dogs
Treatments for Dog Itchiness Include:
Antihistamines can help control your dog's itching from skin allergies, but unfortunately, they don't address the underlying issue causing discomfort. We typically only use them if the itch is very mild.
Zyrtec has become the new first-line drug for dog allergy, largely because of its convenient dosing schedule. Although individual response to antihistamines does vary greatly, this year our clients are seeing a higher response rate than with Benedryl.
Benadryl can be used to treat itchy skin in dogs caused by skin allergies. It also reduces many of the other symptoms of allergies. However, check with your veterinarian for the correct dosage based on your dog's weight and if it might interact with other medication it is taking.
Some common antihistamines for dogs include: Zyrtec (Cetirizine): A popular & safe antihistamine that can be effective in reducing itching and inflammation in dogs. Claratyne (Loratadine): Similar to cetirizine, loratadine can help relieve itching and allergic symptoms in dogs.
To address itchy skin on dogs, bathing one to two times week will suffice. We do not recommend over-bathing a dog with environmental allergies. And while many over-the-counter shampoos may work for your pup, we recommend dog-specific products that can be purchased from your veterinarian.
Quercetin is often considered the strongest natural antihistamine for dogs, helping to manage allergic symptoms by reducing histamine release and supporting immune function. It's a go-to option for natural allergy relief and is commonly used for seasonal allergies and itchy skin.
You may be wondering whether Claritin or Zyrtec is the best pet allergy medicine—but which antihistamine works best for you depends on the severity of your symptoms. For example, a person with a mild allergy to cats or dogs may do well with Claritin. Another person with more severe allergies may do better with Zyrtec.
EFFECTS OF TOXICITY
Large doses of antihistamines can lead to disruption of intestinal smooth muscle function causing gastrointestinal upsets. They can also suppress the respiratory system and impact on the nervous system, causing sedation or excitement.
Cetirizine is considered safe for most dogs. Speak with your vet first to ensure this medication is appropriate for your dog. It is important to only use products that contain cetirizine as the sole active ingredient and avoid human combination products that contain other ingredients that may be toxic to animals.
You can safely give your pet an over-the-counter anti-histamine to relieve their symptoms. The dosage depends on your pet's unique needs and their weight. So, before stuffing any allergy medication into their mouth, check with your veterinarian.
Diphenhydramine (Benadryl®), cetirizine (Zyrtec®), and loratadine (Claritin®) are commonly used antihistamines that relieve allergy symptoms or counteract allergic reactions in humans. Antihistamines are usually safe for dogs but can make some dogs drowsy and others hyperactive.
1. Benadryl for Dogs and Cats (Diphenhydramine)
Omega fatty acids are essential for healthy skin and a shiny coat. They help reduce inflammation, relieve itching, and moisturise the skin. Look for foods that contain fish oils, coconut oil, or flaxseed. We highly recommend our Seafood Bundle to provide your pup with high omega-3 fatty acids in their diet.
fexofenadine (Telfast®) – this is a second gen. It is available as 60 mg capsules and 120 or 180 mg tablets. The dose is 5–10 mg/kg once or twice daily (don't use if your dog is on ketoconazole or a macrolide antibiotic)
Allergex is Chlorpheniramine. Antihistamines are generally well tolerated in dogs and can be used for both short and long-term treatment without the complications associated with other medications like steroids.
Antihistamines: My favorite antihistamines I use in dogs are Zyrtec and Benadryl. Usually, I will start with 5mg Zyrtec in a small dog (under 20 pounds) once a day, and 10mg Zyrtec once a day in medium-sized dogs (who weigh 20-60 pounds), and 10 mg twice a day in larger breed dogs (60+ pounds).
Cetirizine (Zyrtec® or Reactine®) is one of the most commonly used over-the-counter antihistamines recommended by veterinarians. Claritin® can also be used, but many forms of Claritin contain pseudoephedrine, which is a decongestant and is very toxic to dogs.
Yes, you will need a prescription from your vet to get Apoquel for your dog.
Please try the following antihistamines for a minimum of 2-3 weeks. If effective, continue to give them if your dog is itchy (frequently needed only certain times of year, but they can be used year-round).