Both cetirizine (Zyrtec) and loratadine (Claritin) are considered safe for dogs in the right dosage. However, they are also frequently combined with other ingredients like decongestants, which can hurt your dog. Always consult with a vet before giving your dog any new medication.
Antihistamines are usually safe but can make some dogs drowsy and others hyperactive. OTC antihistamine preparations may contain other ingredients such as decongestants that are not safe for dogs. Read the label carefully to ensure that the product only contains antihistamine.
Antihistamines like Benadryl and Zyrtec
ANTI-histamines, such as diphenhydramine (Benadryl®), cetirizine (Zyrtec®), and hydroxyzine, are commonly taken by humans to treat allergy symptoms and can be used for dogs as well. These medications work by preventing histamine from binding to cells and exerting its effects.
Other safe antihistamines for dogs include Claritin (loratadine) and Zyrtec (cetirizine). They produce less sedation than Benadryl does but could still make your dog drowsy. Warning: Make sure your OTC allergy medicine only contains antihistamines.
The dose is 1 mg/kg twice daily. 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)
Fexofenadine, commonly known as Allegra® or Telfast®, is a second generation antihistamine drug that may be used for dogs and cats to control itching and other signs related to allergic conditions.
Cetirizine (Zyrtec® or Reactine®) is one of the most commonly used over-the-counter antihistamines recommended by veterinarians. Claritin® can be used but is not typically recommended by veterinarians as some forms of Claritin® contain decongestants such as pseudoephedrine which is very toxic to dogs.
Here's the recommended Zyrtec dosage for dogs based on their weight: Less than 10 pounds: 2.5 milligrams (half of a 5-milligram pill or a quarter of a 10-milligram pill) 10–50 pounds: One 10-milligram tablet. 50+ pounds: Up to two 10-milligram tablets.
You can safely give Zyrtec to your dog up to 20 mg per day.
Benadryl is a great medication for use in dogs with mild-to-moderate allergies. Seasonal allergies, food allergies, environmental allergies, and allergic reactions to snake and insect bites all respond to Benadryl in most cases.
Zyrtec is one of the safer medications you can give to your dog, so as long as you do so correctly and under your vet's guidance, your pet should be good to go. Zyrtec is also a difficult medication for a dog to overdose on. They have an extremely high tolerance for it, so long as they aren't allergic to it.
Cetirizine (Zyrtec®, Reactine®) is an antihistamine used to treat and prevent pruritus (itching) associated with atopic dermatitis, urticaria (hives), and insect bite reactions in cats and dogs. Its use is in cats and dogs is 'off-label'. Many drugs are commonly prescribed for off-label use in veterinary medicine.
Diphenhydramine (brand name: Benadryl®, Vetadryl®, Banophen®, Genahist®, Diphenhist®, Unisom®, Sominex ®) is an antihistamine used in cats, dogs, ferrets and other small mammals, birds, horses, and cattle to treat allergic reactions, motion sickness, and vomiting.
Recommended Claritin Dosage For Dogs
The recommended dose for Claritin is 0.2 milligrams per pound of body weight every 12-24 hours. This is only a general recommendation, and as with all medication, you should consult with your veterinarian and have them give you the appropriate dose for your individual dog.
Toxicity to pets
When accidentally ingested by dogs and cats, antihistamine poisoning can result in clinical signs of severe agitation, lethargy, sedation, aggression, abnormal heart rate, abnormal blood pressure, vomiting, diarrhea, inappetance, seizures, respiratory depression, and even death.
Antihistamines can be used in dogs to reduce the signs of allergy. The following antihistamines appear safe in dogs (note that Benadryl is no longer sold in Australia as diphenhydramine tablets). These doses have essentially been worked out by trial and error and often scaled down from human doses.
Zyrtec is active for up to 24 hours, so your dog will be free from a runny nose, itchy skin, sneezing, and other symptoms for the whole day. Also, Zyrtec is safer and has fewer side effects than other allergy medicine, which makes it the best remedy for your dog during the spring season.
Diphenhydramine (Benadryl): 1mg per pound (one 25mg tablet for a 25lb dog) twice daily. Cetirizine (Zyrtec) ¼ - ½ mg per pound (one 10mg tab per 30-40 lbs) twice daily.
Pet allergy relief
When you can't live without your pet, a medicine for dog and cat allergies can help control your pet allergy symptoms. ZYRTEC® starts working at hour 1 and stays strong day after day, so you can reduce your cat and dog allergy symptoms.
Zyrtec is a popular second-generation antihistamine first prescribed to people. However, more and more veterinarians have started prescribing it to dogs in pain with pruritus caused by allergic dermatitis. The reason for this is Zyrtec is rather low-risk, however, it's not as effective as the drug Apoquel.
“Zyrtec is found to be more potent, or stronger, in laboratory studies, compared with Claritin,” says Dr. Kung. “It also reaches a higher concentration in the skin, which can be more helpful for skin-related allergies. However, Zyrtec has a greater chance of making you sleepy while taking it.”
The main active ingredient in piriton is chlorpheniramine which is generally safe for dogs, but other brands may have cetirizine hydrochloride which isn't as safe for your pet.
Treating Dog Allergies
Your doctor might recommend: Antihistamines, which block the effects of a chemical that triggers dog allergy symptoms; they're sold over the counter -- like cetirizine (Zyrtec), diphenhydramine (Benadryl), fexofenadine (Allegra), and loratadine (Claritin) -- or by prescription.
Benadryl can be dangerous for your dog if you give too much. An overdose of Benadryl can cause seizures and other side effects. The safest way to give Benadryl is to give it according to the weight of your dog. AKC says the dose for Benadryl is 2 to 4 milligrams per kilogram of body weight, two to three times per day.